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Wind power is the use of wind energy to generate useful work. Historically, wind power was used by sails, windmills and windpumps, but today it is mostly used to generate electricity. Wind power is considered a sustainable, renewable energy source, and has a much smaller impact on the environment compared to burning fossil fuels.

Wind power has been used as long as humans have put sails into the wind. King Hammurabi's Codex (reign 1792 - 1750 BC) already mentioned windmills for generating mechanical energy. Wind-powered machines used to grind grain and pump water, the windmill and wind pump, were developed in what is now Iran, Afghanistan, and Pakistan by the 9th century. Wind power was widely available. Wind-powered pumps drained the polders of the Netherlands, and in arid regions such as the American mid-west or the Australian outback, wind pumps provided water for livestock and steam engines.

The first windmill used for the production of electric power was built in Scotland in July 1887 by Prof James Blyth of Anderson's College, Glasgow (the precursor of Strathclyde University). Blyth's 10 metres (33 ft) high cloth-sailed wind turbine was installed in the garden of his holiday cottage at Marykirk in Kincardineshire, and was used to charge accumulators developed by the Frenchman Camille Alphonse Faure, to power the lighting in the cottage, thus making it the first house in the world to have its electric power supplied by wind power. Blyth offered the surplus electric power to the people of Marykirk for lighting the main street, however, they turned down the offer as they thought electric power was "the work of the devil." Although he later built a wind turbine to supply emergency power to the local Lunatic Asylum, Infirmary, and Dispensary of Montrose, the invention never really caught on as the technology was not considered to be economically viable.

Across the Atlantic, in Cleveland, Ohio, a larger and heavily engineered machine was designed and constructed in the winter of 1887-1888 by Charles F. Brush. This was built by his engineering company at his home and operated from 1886 until 1900. The Brush wind turbine had a rotor 17 metres (56 ft) in diameter and was mounted on an 18 metres (59 ft) tower. Although large by today's standards, the machine was only rated at 12 kW. The connected dynamo was used either to charge a bank of batteries or to operate up to 100 incandescent light bulbs, three arc lamps, and various motors in Brush's laboratory.

With the development of electric power, wind power found new applications in lighting buildings remote from centrally generated power. Throughout the 20th century parallel paths developed small wind stations suitable for farms or residences.

From 1932 many isolated properties in Australia ran their lighting and electric fans from batteries, charged by a "Freelite" wind-driven generator, producing 100watts of electrical power from as little wind speed as 10 miles per hour (16 km/h).

The 1973 oil crisis triggered the investigation in Denmark and the United States that led to larger utility-scale wind generators that could be connected to electric power grids for remote use of power. By 2008, the U.S. installed capacity had reached 25.4 gigawatts, and by 2012 the installed capacity was 60 gigawatts.

Today, wind-powered generators operate in every size range between tiny stations for battery charging at isolated residences, up to gigawatt-sized offshore wind farms that provide electric power to national electrical networks.

Wind farms and how they work

Wind is air movement in the earth's atmosphere. To convert the kinetic energy of wind into mechanical energy, which is then converted into electrical energy, wind turbines are used. The basic components of a wind turbine include a rotor, blades, a shaft, a gearbox, a generator, and a tower.

Wind turns the blades, which spins a rotor that is connected to a generator. The output of the generator is collected through electric power cables.

Turbines are generally grouped into wind farms and connected to the electrical grid. A wind farm is a group of wind turbines in the same location. A large wind farm may consist of several hundred wind turbines. In general, a distance of 7D (7 times the rotor diameter of the wind turbine) is set between each turbine in a fully developed wind farm. The land between the turbines may be used for agricultural or other purposes. A wind farm may also be located offshore.

Almost all large wind turbines have the same design - a horizontal axis wind turbine having an upwind rotor with 3 blades, attached to a nacelle on top of a tall tubular tower.

Offshore wind power

Offshore wind power is wind farms in large bodies of water, usually the sea. These farms have less visual impact on the landscape than land-based projects. However, the construction and maintenance costs are considerably higher.

As of November 2021, the Hornsea Wind Farm in the United Kingdom is the largest offshore wind farm in the world at 1,218 MW.

Small-scale wind power

Small-scale wind power is the name given to wind generation systems with the capacity to produce up to 50 kW of electrical power. Isolated communities, that may otherwise rely on diesel generators, may use wind turbines as an alternative. Individuals may purchase these systems to reduce or eliminate their dependence on grid electric power for economic reasons, or to reduce their carbon footprint. Wind turbines have been used for household electric power generation in conjunction with battery storage over many decades in remote areas.

Examples of small-scale wind power projects in an urban setting can be found in New York City, where, since 2009, several building projects have capped their roofs with Gorlov-type helical wind turbines. Although the energy they generate is small compared to the buildings' overall consumption, they help to reinforce the building's 'green' credentials in ways that "showing people your high-tech boiler" cannot, with some of the projects also receiving the direct support of the New York State Energy Research and Development Authority.

Impact on environment and landscape

Advantages

Wind power stations have the advantage over fossil fue power stations as they do not produce any greenhouse gases such as carbon dioxide or water vapour. They also do not produce gases that helps to make acid rain, such as sulphur dioxide. They also make the environment safer and less pollution is caused.

Disadvantages

Wind turbines have to be carefully placed. They must be in positions where there is a constant, steady supply of wind. In fact, the wind must not become too strong or it may damage the turbine. Because wind is uncontrollable, so is the amount of power that wind turbines will produce, making them a possibly unreliable source of energy.

Onshore wind farms can have a significant visual impact. Also, wind farms typically need to be spread over more land than other power stations and need to be built away from urban areas. Some wind farms can potentially spoil protected scenic areas, archaeological landscapes and heritage sites. A report by the Mountaineering Council of Scotland concluded that wind farms harmed tourism in areas known for natural landscapes and panoramic views.

Wind farms have a negative impacts on wildlife. Thousands of birds and bats, including rare species, have been killed by wind turbine blades, though wind turbines are responsible for far fewer bird deaths than fossil-fueled power stations. This can be mitigated with proper wildlife monitoring.

Many wind turbine blades are made of fiberglass, and have a lifetime of 20 years. However, many of them are non-recyclable.

Interesting facts about wind power

In 2021, wind supplied over 1800 TWh of electricity, which was over 6% of world electricity and about 2% of world energy.

Wind power is one of the lowest-cost electricity sources per unit of energy produced.

Regions in the higher northern and southern latitudes have the highest potential for wind power.

In most regions, wind power generation is higher in nighttime and in winter.

In 1919, the German physicist Albert Betz showed that for a hypothetical ideal wind-energy extraction machine, the fundamental laws of conservation of mass and energy allowed no more than 16/27 (59%) of the kinetic energy of the wind to be captured.

Wind power is variable, and during low wind periods, it may need to be replaced by other power sources.

The energy payback time of a wind farm is typically around a year.

An estimated 1.25 million people were employed in wind power in 2020.

Wind turbines generate noise. At a distance of 300 metres (980 ft), this may be around 45 dB, which is slightly louder than a refrigerator. At 1.5 km (1 mi), they become inaudible.

There are anecdotal reports of negative health effects on people who live very close to wind turbines. Peer-reviewed research has generally not supported these claims.

Wind cannot be cut off unlike oil and gas so can contribute to energy security.

Surveys of public attitudes across Europe and in many other countries show strong public support for wind power.

In Spanish: Energía eólica para niños

Images for kids

Wind turbines such as these, in Cumbria, England, have been opposed for a number of reasons, including aesthetics, by some sectors of the population.

A panoramic view of the United Kingdom's Whitelee Wind Farm with Lochgoin Reservoir in the foreground.

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Hydropower-energy created from fresh, moving water-is the world's oldest form of renewable energy.

Over 2,000 years ago, the ancient Greeks used the power in rivers and streams to rotate wooden wheels and crush grain to make bread. Today, we still use this water power to generate clean, affordable electricity for everything from factories (that grind far more grain than the Greeks did) to our ovens that let us bake our bread at home.

What Is Hydropower?

Humans have used water power for centuries. But we didn't start making hydropower-electricity from our rivers, streams, and lakes-until just over 100 years ago, not too long after Thomas Edison invented electric power. Today, instead of using large, wooden wheels, we use propeller-like devices called turbines, which spin as water rushes through them, generating electricity. But hydropower has a secret power: It can also store huge amounts of renewable energy to use when other sources dry up.

Right now, hydropower provides about 7% of the United States' electricity and about 40% of our renewable energy. And almost every state uses it. The oldest form of renewable energy, it's also one of the most affordable and can provide a clean, sustainable, and reliable way to power our lives for centuries to come.

In the past, we often created hydropower with large dams, but today's structures are typically far smaller, which means they can better protect fish and other critical wildlife and plants that depend on these waters to survive. Photo from Mark König, Unsplash

How Does Hydropower Work?

Most of the country's hydropower facilities were built in lakes, streams, and rivers decades ago. They often used large dams that block the water's flow, creating a pool of water above the structure. One or more pipes give that pooled water a path to surge downhill. And as the water rushes through those pipes, it spins a turbine, which runs a generator that sends clean electricity to your home.

Today, most newly constructed hydropower facilities are far smaller and use new techniques to better protect the wildlife and plants that rely on naturally flowing waterways. Fish, for example, must migrate upstream to feed and mate. To help them navigate around our dams, we build fish ladders, so they can climb over the top and swim on. Or we don't block their path at all; some new hydropower facilities divert part of a river or stream into a separate channel. That way, the river and its ecosystem can race on, undisturbed, while we generate power off to the side.

Some hydropower facilities don't just generate power; they store it in the largest "batteries" on Earth. So-called pumped storage hydropower-also known as water batteries-can hold huge amounts of renewable energy for months at a time. This storage is very important. Solar energy and wind power only create electricity when the sun shines and winds blow, but water batteries can store excess energy that can be used at night or during gentle breezes. In the United States, they can store up to 553 gigawatt-hours of energy. That could power the entire country's video gaming for about a week.

Pumped storage hydropower can be either open (left) or closed loop (right). Because closed-loop pumped storage hydropower does not connect to natural waterways, this newer technology can help protect local water quality and ecosystems. Illustration by NREL

What Makes Hydropower So Great?

Hydropower costs less than most other energy sources, making it an affordable source of renewable energy. Except during periods of extreme drought, we can count on water to flow day and night and all year round. And this consistency is critical if we want to rely purely on clean energy sources, such as solar energy and wind power, which can come and go.

New hydropower technologies keep getting better, too. They make it easier to build new facilities without too much disruption to the local environment. And they help cut construction costs, which could make hydropower even more affordable, potentially reducing energy bills across the country.

Hydropower facilities can also control how much water flows through their turbines and, therefore, how much energy they produce and when. That way, hydropower can fill energy gaps to ensure communities always get the power they need-or restore it. When ice storms, wildfires, or even hackers stop the electric grid from lighting up our lives, hydropower can help. In almost half of all blackouts, it's water that turns the lights back on. Losing power during a heat wave or at a hospital is not just inconvenient; it can be dangerous. Hydropower can save lives.

What Else Can Hydropower Do?

Water housed in hydropower facilities can be used to water crops, put out wildfires, or provide clean drinking water to local communities.

In some areas, such as the drier Western states, the warming climate is likely to cause more droughts, which could threaten water supplies. Because hydropower facilities can absorb and store extra water, they can help communities manage their supplies. In the Northeast, on the other hand, climate change is likely to cause more flooding. Hydropower can help with that, too. Its reservoirs can capture dangerous run-off, preventing those waters from surging into towns and cities where it can threaten properties and lives.

Additional Resources

For more information about hydropower, browse the following resources.

NREL's Hydropower Research - news and updates about NREL's hydropower studies and innovations

An Examination of the Hydropower Licensing and Federal Authorization Process, NREL Technical Report (2021)

Hydropower Fact Sheet, U.S. Department of Energy's Water Power Technologies Office (2021)

Hydropower Basics
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy

How Hydropower Works
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy

Hydropower Stories
In the 1970s, Hydropower Was Gold. What Happened? Hydropower Means Flexible Power for Our Clean Energy Future FLASH: Meet the New Superhero of Hydropower RAPID Changes Are Coming for Hydropower NREL Announces Winners of the Groundbreaking Hydro Prize
Read more stories about how hydropower could help communities take charge of their energy production, save money, and support a healthy planet.

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Hydropower-energy created from fresh, moving water-is the world's oldest form of renewable energy. Over 2,000 years ago, the ancient Greeks used the power in rivers and streams to rotate wooden wheels and crush grain to make bread.

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Hydroelectricity is electricity that is made by the movement of water. It is usually made with dams that block a river to make a reservoir or collect water that is pumped there. When the water is "let go", the huge pressure behind the dam forces the water down pipes that lead to a turbine. This causes the turbine to turn, which turns a generator which makes electricity. This use of renewable energy produces less pollution than steam engines do. Some places such as Norway and Quebec get most of their electricity this way.

Hydroelectric power plants

Generating methods

Conventional (dams)

Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. A large pipe (the "penstock") delivers water from the reservoir to the turbine.

Pumped-storage

This method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, the excess generation capacity is used to pump water into the higher reservoir. When the demand becomes greater, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently provide the most commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system. Pumped storage is not an energy source, and appears as a negative number in listings.

Run-of-the-river

Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that only the water coming from upstream is available for generation at that moment, and any oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream is a significant advantage in choosing sites for run-of-the-river. In the United States, run of the river hydropower could potentially provide 60,000 megawatts (80,000,000 hp) (about 13.7% of total use in 2011 if continuously available).

A tidal power station makes use of the daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot water wheels. Tidal power is viable in a relatively small number of locations around the world. In Great Britain, there are eight sites that could be developed, which have the potential to generate 20% of the electricity used in 2012.

Sizes, types and capacities of hydroelectric facilities

Large facilities

Large-scale hydroelectric power stations are more commonly seen as the largest power producing facilities in the world, with some hydroelectric facilities capable of generating more than double the installed capacities of the current largest nuclear power stations.

Although no official definition exists for the capacity range of large hydroelectric power stations, facilities from over a few hundred megawatts are generally considered large hydroelectric facilities.

Currently, only four facilities over () are in operation worldwide, see table below.

Small hydro is the development of hydroelectric power on a scale serving a small community or industrial plant. The definition of a small hydro project varies but a generating capacity of up to 10 megawatts (MW) is generally accepted as the upper limit of what can be termed small hydro. This may be stretched to 25 MW and 30 MW in Canada and the United States. Small-scale hydroelectricity production grew by 28% during 2008 from 2005, raising the total world small-hydro capacity to . Over 70% of this was in China (65 GW), followed by Japan (3.5 GW), the United States (3 GW), and India (2 GW).

Small hydro stations may be connected to conventional electrical distribution networks as a source of low-cost renewable energy. Alternatively, small hydro projects may be built in isolated areas that would be uneconomic to serve from a network, or in areas where there is no national electrical distribution network. Since small hydro projects usually have minimal reservoirs and civil construction work, they are seen as having a relatively low environmental impact compared to large hydro. This decreased environmental impact depends strongly on the balance between stream flow and power production.

Micro hydro is a term used for hydroelectric power installations that typically produce up to of power. These installations can provide power to an isolated home or small community, or are sometimes connected to electric power networks. There are many of these installations around the world, particularly in developing nations as they can provide an economical source of energy without purchase of fuel. Micro hydro systems complement photovoltaic solar energy systems because in many areas, water flow, and thus available hydro power, is highest in the winter when solar energy is at a minimum.

Pico hydro is a term used for hydroelectric power generation of under . It is useful in small, remote communities that require only a small amount of electricity. For example, to power one or two fluorescent light bulbs and a TV or radio for a few homes. Even smaller turbines of 200-300W may power a single home in a developing country with a drop of only 1 m (3 ft). A Pico-hydro setup is typically run-of-the-river, meaning that dams are not used, but rather pipes divert some of the flow, drop this down a gradient, and through the turbine before returning it to the stream.

Underground

An underground power station is generally used at large facilities and makes use of a large natural height difference between two waterways, such as a waterfall or mountain lake. An underground tunnel is constructed to take water from the high reservoir to the generating hall built in an underground cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway.

Advantages of hydroelectricity

The way the electricity is produced does not harm the environment as much as fossil fuels like oil or coal do. Hydroelectricity is very powerful and safe, and produces no waste.

Hydroelectricity can be made very quickly. This makes it useful for times when demand for electricity is high. Water that has been stored in a reservoir can be released (let go) when needed, so the energy can be made quickly. This controllability also makes hydroelectricity a good match for less controllable intermittent energy sources. When the wind is not blowing or the sun is not shining, hydroelectricity can be released.

Another advantage is that hydroelectricity cannot run out as long as there is a good water supply. Once the dam is built, the electricity costs very little, no waste or pollution is produced, and electricity can be generated whenever it is needed.

A few hydro turbines do not have a dam but instead use the current of the "run of the river". They produce less electricity and cannot store energy for later use.

Disadvantages of hydroelectricity

The building of large dams to hold water can damage the environment. In 1983, the Australian government stopped the Tasmanian state government from building a dam on the Gordon River in Tasmania after a huge public protest. The dam would have flooded the beautiful Franklin River. The Three Gorges Dam in China will be the world's largest hydroelectricity project. The dam has flooded a huge area, meaning that 1.2 million people have had to be moved. Scientists are concerned about many problems with the dam, such as pollution, silt, and the danger of the dam wall breaking.

Images for kids

The Three Gorges Dam in Central China is the world's largest power-producing facility of any kind.

Museum Hydroelectric power plant ″Under the Town″ in Serbia, built in 1900.

The Warwick Castle water-powered generator house, used for the generation of electricity for the castle from 1894 until 1940

The Ffestiniog Power Station can generate of electricity within 60 seconds of the demand arising.

Merowe Dam in Sudan. Hydroelectric power stations that use dams submerge large areas of land due to the requirement of a reservoir. These changes to land color or albedo, alongside certain projects that concurrently submerge rainforests, can in these specific cases result in the global warming impact, or equivalent life-cycle greenhouse gases of hydroelectricity projects, to potentially exceed that of coal power stations.

The Hoover Dam in the United States is a large conventional dammed-hydro facility, with an installed capacity of .

Trends in the top five hydroelectricity-producing countries

In Spanish: Hidroelectricidad para niños

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Solar energy is a powerful source of energy that can be used to heat, cool, and light homes and businesses.

More energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. A variety of technologies convert sunlight to usable energy for buildings. The most commonly used solar technologies for homes and businesses are solar photovoltaics for electricity, passive solar design for space heating and cooling, and solar water heating.

Businesses and industry use solar technologies to diversify their energy sources, improve efficiency, and save money. Energy developers and utilities use solar photovoltaic and concentrating solar power technologies to produce electricity on a massive scale to power cities and small towns.

Learn more about the following solar technologies:

Converts sunlight directly into electricity to power homes and businesses.

Provides light and harnesses heat from the sun to warm our homes and businesses in winter.

Harnesses heat from the sun to provide hot water for homes and businesses.

Uses solar energy to heat or cool commercial and industrial buildings.

Harnesses heat from the sun to provide electricity for large power stations.

Additional Resources

For more information about solar energy, visit the following resources:

Solar Energy Technology Basics
U.S. Department of Energy Office of Energy Efficiency & Renewable Energy
U.S. Department of Energy Solar Decathlon
Energy Kids Solar Basics
U.S. Energy Information Administration Energy Kids

Clean Energy Education and Professional Development
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy

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Solar energy is a powerful source of energy that can be used to heat, cool, and light homes and businesses. More energy from the sun falls on the earth in one hour than is used by everyone in the world in one year. A variety of technologies convert sunlight to usable energy for buildings.

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Wind is the largest source of renewable energy in the United States, providing clean electricity from land and offshore to individual homes, remote farms, small communities and large cities alike.

Wind energy is old-so old that ancient Egyptians used this bountiful, blustery resource, according to the U.S. Energy Information Administration, to propel their boats down the Nile River. The first wind turbines (or windmills, as they were originally called) were made from abundant materials, such as wood or reeds, which were woven into tight blades and spun to pump water for farms, grind grain, and, eventually, power entire communities.

Today's wind turbines use sleek, modern materials to generate clean, renewable energy almost anywhere in the world.

What Is Wind Energy?

To answer this question, it's best to start with another: What is wind?

Wind is born when pockets of the Earth's craggy surface get different amounts of sun and cool or heat faster than others nearby. To balance those differences, like mixing hot and cold water in a bathtub, air moves around the world-gaining or losing speed as it dips through valleys and sprints over rivers. That creates-you guessed it-wind.

Wind can be powerful enough to whisk birds through the sky, move sailboats across the ocean, and even rip trees from the ground. In comparison to all that, pushing wind turbine blades is easy! It's that movement of the turbines that creates electricity.

Want to know how much wind energy is humming across your state? Check out NREL's wind maps on WINDExchange.

How Do Wind Turbines Work?

Wind turbines, like windmills, catch the wind's energy with propeller-like blades. These blades can have a horizontal axis, like a fan, or vertical one, like a merry-go-round. The most common design is a tall tower with three large blades on a horizontal axis. But some vertical-axis wind turbines look like eggbeaters, while others look like the windmills that populated farms a century ago.

Unlike fans, which use electricity to move air, wind turbines use moving air to generate electricity. When the wind blows, its force turns the blades, which runs a generator and creates clean electricity. But some turbine designs can produce more clean energy than others. For example, because winds can be more powerful and less volatile higher in the atmosphere, placing turbines on towers 100 feet (or 30 meters) tall-about the height of the Statue of Liberty-can help them generate more electricity. Wind turbine operators can also shift their machines to face directly into the wind-a technique called yawing.

Can't picture this? Watch the U.S. Department of Energy's wind energy animation to see wind turbines in action.

How Do We Get Our Wind Energy?

There are several ways to get power from wind energy. Wind turbines can be built on land, on lakes or in the ocean, in remote wilderness far from the power grid, within cities, or across vast plains.

One wind turbine can power an individual home or farm, but several built close together form a wind energy plant, or wind farm. Wind plants can be land-based or offshore, and they can be hybrid plants (meaning, they include other sources of energy, such as solar energy). Wind energy researchers are trying to learn how many wind turbines built in which arrangements can maximize energy production in wind plants.

Today, most grid-connected wind plants are at least 1 megawatt or larger. The biggest wind farm in the United States spans 100,000 acres (enough to cover half of New York City) and can power more than 250,000 homes.

What Are the Major Applications of Wind Energy?

Wind energy has three major applications: land-based, distributed, and offshore.

Land-Based Wind Energy Is the Most Common

The majority of turbines are installed on land. And land-based wind energy is one of the lowest-cost sources of electricity generation, as highlighted by the U.S. Department of Energy.

Researchers at NREL are categorizing wind resources on land and advancing wind turbines to more efficiently generate electricity at even lower cost.

Distributed Wind Energy Powers Remote and Local Communities

Distributed wind energy is a distributed energy resource, meaning it produces a smaller-scale unit of power. In this case, it comprises one or more wind turbines, which range from a kilowatt to several megawatts in capacity.

These typically land-based turbines operate locally to provide energy for individual buildings or small communities, though they can be connected to a power grid at the distribution level. Some wind turbines can even pop up as mobile, on-demand sources of clean power in disaster or defense scenarios.

Homeowners, farmers, businesses, and industries make use of clean, distributed wind energy to pump water (to use as drinking water, to irrigate farms, and more), to lower electric bills, and to reduce air pollution.

Distributed wind turbines are improving all the time, growing stronger, less costly, more resilient, and more efficient.

Offshore Wind Energy Is Newer but Growing

Wind turbines used in offshore wind energy can be even larger than on land, with towers one-and-a-half-times the height of the Washington Monument and blades as long as a football field (as noted in to the U.S. Department of Energy's list of 10 things you may not have known about wind energy).

These behemoths depend on strong sea breezes to spin turbines that are either anchored to the seafloor (called fixed-bottom wind turbines) or installed on platforms that float (called floating wind turbines). Offshore wind turbines can provide electricity to power ocean-based research and equipment, such as unmanned robots used for marine exploration; remote or island communities disconnected from the grid; or entire cities back on land.

The offshore wind energy industry is growing. Researchers are identifying massive amounts of potential wind energy off U.S. coastlines, and the Biden administration has set a goal to install 30 gigawatts of wind energy by 2030. That will require us to grow the offshore wind energy workforce as well as the supply chain to build and infrastructure to deploy new offshore wind farms.

The U.S. Department of Energy indicates that, as of 2022, nearly 80% of the nation's electricity is used to power our coastal and Great Lakes states, where most Americans live. So, even though offshore wind energy is a relatively new industry in the United States, it could soon provide clean, renewable electricity to many U.S. communities. America's first offshore wind farm, located off the coast of Rhode Island, powered up in December 2016. Today, many more projects are in development along the U.S. East Coast that could send power back to the grid. And, with technology advancements for floating offshore wind energy, wind farms are coming to the West Coast as well.

Why Do We Need Wind Energy?

Wind energy is one of the largest sources of clean, renewable energy in the United States, making it essential to a future carbon-free energy sector. Wind turbines do not release emissions that pollute our air or water, and they can be built with minimal impact to the environment or livelihoods of nearby residents. Farmers and ranchers, for example, can lease their land to wind farms and, because the turbines take up minimal space, continue to grow crops or raise livestock while earning a steady income.

But wind energy can be even better.

The wind energy industry is working to figure out what areas of research need more attention to expand the use of wind energy. This includes understanding how wind interacts with a turbine behind (downwind from) another one, evaluating the best ways to verify new technologies, and incorporating feedback from communities living near or using wind turbines.

Researchers are studying different materials and designs that could make wind turbine blades lighter, longer, more durable, and better at creating energy. New technologies could also make wind turbines less expensive to manufacture, install, operate, and maintain, making wind energy more accessible to more people. As a bonus, some new materials and processes could make wind turbines more reusable or recyclable, which can cut down on waste, too.

Scientists are also studying ways to limit the impact wind turbines can have on wildlife. For example, sound and light could warn birds and bats to fly around wind turbines. And even though wind turbines must be installed far enough from homes that they produce noise no louder than a refrigerator's hum, researchers have discovered ways to further reduce their noise levels. Because wind turbines are a significant source of clean energy, they lower pollution to help keep the Earth (and, therefore, its birds, bats, and humans) healthy.

Additional Resources

For more information, visit NREL's Wind Energy Research site or the following resources:

Wind Energy Basics
U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy

Small Wind Electric Systems
U.S. Department of Energy's Energy Savers Program

Wind Energy Educational Resources
U.S. Department of Energy's WINDExchange Initiative

U.S. Department of Energy's WINDExchange Initiative.

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Learn about the history of wind energy and how wind turbines use wind energy to generate electricity.

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[updated March 2021]
Solar experts and installers have found that when a family decides to install rooftop solar panels on their home, their children understandably become interested in solar energy and solar power systems. We want to help parents explain solar power and the benefits of solar energy systems to their kids. However, the complexities of solar energy can quickly become confusing, even for adults. So we broke down and simplified some main points about solar power and provided fun facts specifically catered to interest kids!

Kid-Friendly Solar Energy Facts

The sun is full of energy and solar energy comes from sunlight that reaches earth! The amount of sunlight that reaches earth varies depending on location, time of day, time of year, and weather conditions.

The sun has produced energy for billions of years! This means solar energy has been used by people for hundreds of years to cook food, keep warm, and to dry clothes. Today, it is also used to create electricity.

Solar cells turn light from the sun into electricity. Solar cells are also called photovoltaic cells. 'Photo' is Latin for light and 'voltaic' means electricity.

Solar cells are put together to make solar panels, sometimes called a "solar array." Solar panels are put on your home's roof to collect sunlight and turn it into power. If you have seen big shiny panels on the roof of a house, that house is using solar energy! Solar energy can be used to power anything in your house that needs electricity.
Watch Bill Nye Explain How it Works!
Solar Panels are not just for houses. In fact, solar panels are used all around us to power many different things. Solar panels can be put on food trucks, cars, boats, buildings and space satellites. There are even planes that run on solar power! Solar panels can also be used to power smaller things such as calculators and the orange flashing highway signs that warn us about a traffic jam or a closed exit.

Solar energy is good for the planet! It does not create pollution like energy from coal and oil. We waste energy to make power from coal and oil. No energy is wasted when using solar power!

Solar is our energy future, so it only makes sense to teach the future generation about the benefits of the sustainable energy source. If you are interested in installing solar PV panels on your roof, talk to your kids or younger siblings about it! We think you'll be surprised by their response! Who knows, your talk may even spark an interest in a future solar career!

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Solar Energy for Kids - Renewable Energy World

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updated March 2021] Solar experts and installers have found that when a family decides to install rooftop solar panels on their home, their children understandably become interested in solar energy and solar power systems. We want to help parents explain solar power and the benefits of solar energy systems to their kids.

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Energy forms are either potential or kinetic. Potential energy comes in forms that are stored and includes chemical, gravitational, mechanical, and nuclear. Kinetic energy is energy in movement and includes electrical energy, heat, light, and sound.

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Energy forms are either potential or kinetic. Potential energy comes in forms that are stored and includes chemical, gravitational, mechanical, and nuclear. Kinetic energy is energy in movement and includes electrical energy, heat, light, and sound.

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Coal takes millions of years to form

Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.

Layers of dirt and rock covered the plants over millions of years. The resulting pressure and heat turned the plants into the substance we call coal.

Types of coal

Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite. The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce. The rank of a coal deposit is determined by the amount of pressure and heat that acted on the plants over time.

Anthracite contains 86%-97% carbon and generally has the highest heating value of all ranks of coal. Anthracite accounted for less than 1% of the coal mined in the United States in 2020. All of the anthracite mines in the United States are in northeastern Pennsylvania. Anthracite is mainly used by the metals industry.

Bituminous coal contains 45%-86% carbon. Bituminous coal in the United States is between 100 million and 300 million years old. Bituminous coal is the most abundant rank of coal found in the United States, and it accounted for about 44% of total U.S. coal production in 2020. Bituminous coal is used to generate electricity and is an important fuel and raw material for making iron and steel. Bituminous coal was produced in at least 18 states in 2020, but five states accounted for about 74% of total bituminous production: West Virginia (28%), Pennsylvania (14%), Illinois (13%), Kentucky (10%), and Indiana (8%).

Subbituminous coal typically contains 35%-45% carbon, and it has a lower heating value than bituminous coal. Most subbituminous coal in the United States is at least 100 million years old. About 46% of total U.S. coal production in 2020 was subbituminous and about 88% was produced in Wyoming and 8% in Montana. The remainder was produced in Alaska, Colorado, and New Mexico.

Lignite contains 25%-35% carbon and has the lowest energy content of all coal ranks. Lignite coal deposits tend to be relatively young and were not subjected to extreme heat or pressure. Lignite is crumbly and has high moisture content, which contributes to its low heating value. Lignite accounted for 9% of total U.S. coal production in 2020. About 54% was mined in North Dakota and about 39% was mined in Texas. The other 7% was produced in Louisiana, Mississippi, and Montana. Lignite is mostly used to generate electricity. A facility in North Dakota also converts lignite to synthetic natural gas and pipes it to natural gas consumers in the eastern United States.

Mining coal

Coal miners use large machines to remove coal from the earth. Many U.S. coal deposits, called coal beds or seams, are near the earth's surface, while others are deep underground. Modern mining methods allow coal miners to easily reach most of the nation's coal reserves and to produce about three times more coal in one hour than in 1978.

Coal miners use two primary methods to remove coal

Surface mining is often used when coal is less than 200 feet underground. In surface mining, large machines remove the topsoil and layers of rock known as overburden to expose coal seams. Mountaintop removal is a form of surface mining where the tops of mountains are dynamited and removed to access coal seams. Once the coal is removed, the disturbed area may be covered with topsoil for planting grass and trees. About two-thirds of U.S. coal production is from surface mines because surface mining is less expensive than underground mining.

Underground mining, sometimes called deep mining, is necessary when the coal is several hundred feet below the surface. Some underground mines are thousands of feet deep with tunnels that may extend out from the vertical mine shafts for miles. Miners ride elevators down deep mine shafts and travel on small trains in long tunnels to get to the coal. The miners use large machines to dig out the coal.

Processing coal

After removing the coal from the ground, the miners may send it to a preparation plant near the mining site. The plant cleans and processes coal to remove rocks, dirt, ash, sulfur, and other unwanted materials. This process increases the heating value of the coal.

A train transporting coal

Transporting coal

Conveyors, trams, and trucks move coal around mines, short distances from mines to consumers close to the mines, or to other modes of long-distance transportation.

Trains transport nearly 70% of coal deliveries in the United States for at least part of the way from mines to consumers.

Barges transport coal on rivers and lakes.

Ships transport coal on the Great Lakes and the oceans to consumers in the United States and other countries.

Slurry pipelines move mixtures of crushed coal and water. This method is not currently in use in the United States.

Transporting coal can be more expensive than the cost of mining coal. Some coal consumers, such as coal-fired electric power plants, are near coal mines to lower transportation costs.

Where the United States gets its coal

Did you know?

In 2020, about 535 million short tons of coal were produced in 22 U.S. states. Surface mines were the source of 63% of total U.S. coal production and accounted for 63% of the total number of coal mines. About 0.4 million tons, or about 0.1% of total coal production, was refuse recovery coal.

Coal is mainly found in three regions: the Appalachian coal region, the Interior coal region, and the Western coal region (includes the Powder River Basin).

Facts and data for each coal-producing region for 2020

The Appalachian coal region includes Alabama, Eastern Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia.

About 26% of the coal produced in the United States came from the Appalachian coal region.

West Virginia is the largest coal-producing state in the region and the second-largest coal-producing state in the United States.

Underground mines supplied 81% of the coal produced in the Appalachian region.

Underground mines in the Appalachian region produced 58% of U.S. total underground coal mine production.

The Interior coal region includes Arkansas, Illinois, Indiana, Kansas, Louisiana, Mississippi, Missouri, Oklahoma, Texas, and Western Kentucky.

About 17% of total U.S. coal was mined in the Interior coal region.

Illinois was the largest coal producer in the Interior coal region, accounting for 35% of the region's coal production and 6% of total U.S. coal production.

Underground mines supplied 60% of the region's coal production and surface mines supplied 40%.

The Western coal region includes Alaska, Arizona, Colorado, Montana, New Mexico, North Dakota, Utah, Washington, and Wyoming.

About 57% of total U.S. coal production was mined in the Western coal region.

Wyoming, the largest coal-producing state in the United States, produced 41% of total U.S. coal production and 71% of the coal mined in the Western coal region.

Eight of the top ten largest U.S. coal producing mines were in Wyoming, and all of those mines are surface mines.

Surface mines produced 91% of the coal in the Western coal region.

In 2021, about 546 million short tons (MMst) of coal were consumed in the United States. On an energy content basis, this amount was equal to about 10.5 quadrillion British thermal units (Btu) and to about 11% of total U.S. energy consumption. Although coal use was once common in the industrial, transportation, residential, and commercial sectors, today the main use of coal in the United States is to generate electricity. The electric power sector accounts for most of U.S. coal consumption. U.S. coal consumption peaked in 2007 and has declined in most years since then, mainly because of a decline in the use of coal for electricity generation.

Electric power-501.4 MMst-91.9%

Industrial total-43.4 MMst-8.0%

Industrial coke plants-17.6 MMst-3.2%

Industrial combined heat and power-10.0 MMst-1.8%

Other industrial-15.9 MMst-2.9%

Commercial-0.8 MMst-1%

Residential and transportation-each less than 1 MMst-less than 1%

Electric power

Power plants make steam by burning coal, and the steam turns turbines (machines for generating rotary mechanical power) to generate electricity.

Many industries and businesses have their own power plants, and some use coal to generate electricity, mostly in combined heat and power plants.

Industry

Many industries use coal and coal byproducts. The concrete and paper industries burn large amounts of coal to produce heat. The steel industry uses coal indirectly to make steel. Coal coke is made by baking coal in furnaces. The steel industry uses coal coke to smelt iron ore into iron to make steel. The high temperatures created by burning coal coke give steel the strength and flexibility needed for bridges, buildings, and automobiles.

Did you know?

Converting coal into gas and liquids

Coal can be turned into gases and liquids that can be used as fuels or processed into chemicals to make other products. These gases or liquids are sometimes called synthetic fuels or synfuels. Synthetic fuels are made by heating coal in large vessels. These fuels produce fewer air pollutants when burned than burning coal directly.

In North Dakota, the Great Plains Synfuels Plant converts coal into synthetic natural gas (syngas). Syngas produced from coal can also be used to produce electricity and hydrogen. Currently, no commercially operating facilities in the United States produce liquids from coal, but coal has been converted to liquids in South Africa for decades.

Coal is an abundant fuel source that is relatively inexpensive to produce and convert to useful energy. However, producing and using coal affects the environment.

Effects of coal mining

Surface mines (sometimes called strip mines) were the source of about 62% of the coal mined in the United States in 2019. These mining operations remove the soil and rock above coal deposits, or seams. The largest surface mines in the United States are in Wyoming's Powder River Basin, where coal deposits are close to the surface and are up to 70 feet thick.

Mountaintop removal and valley fill mining has affected large areas of the Appalachian Mountains in West Virginia and Kentucky. In this form of coal extraction, the tops of mountains are removed using explosives. This technique changes the landscape, and streams are sometimes covered with rock and dirt. The water draining from these filled valleys may contain pollutants that can harm aquatic wildlife downstream. Although mountaintop mining has existed since the 1970s, its use became more widespread and controversial beginning in the 1990s.

U.S. laws require that dust and water runoff from areas affected by coal mining operations must be controlled, and the area must be reclaimed close to its original condition.

Underground mines generally affect the landscape less than surface mines. However, the ground above mine tunnels can collapse, and acidic water can drain from abandoned underground mines.

Methane gas that occurs in coal deposits can explode if it concentrates in underground mines. This coalbed methane must be vented out of mines to make mines safer places to work. In 2020, methane emissions from coal mining and abandoned coal mines accounted for about 7% of total U.S. methane emissions and about 1% of total U.S. greenhouse gas emissions (based on global warming potential). Some mines capture and use or sell the coalbed methane extracted from mines.

Emissions from burning coal

Sulfur dioxide (SO₂), which contributes to acid rain and respiratory illnesses

Nitrogen oxides (NOx), which contribute to smog and respiratory illnesses

Particulates, which contribute to smog, haze, and respiratory illnesses and lung disease

Carbon dioxide (CO₂), which is the primary greenhouse gas produced from burning fossil fuels (coal, oil, and natural gas)

Mercury and other heavy metals, which have been linked to both neurological and developmental damage in humans and other animals

Fly ash and bottom ash, which are residues created when power plants burn coal

In the past, fly ash was released into the air through the smokestack, but laws now require that most emissions of fly ash be captured by pollution control devices. In the United States, fly ash and bottom ash are generally stored near power plants or placed in landfills. Pollution leaching from ash storage and landfills into groundwater and several large impoundments of ash that ruptured are environmental concerns.

Reducing the environmental effects of coal use

The Clean Air Act and The Clean Water Act require industries to reduce pollutants released into the air and water.

The coal industry has found several ways to reduce sulfur and other impurities from coal. The industry has also found more effective ways of cleaning coal after it is mined, and some coal consumers use low sulfur coal.

Power plants use flue gas desulfurization equipment, also known as scrubbers, to clean sulfur from the smoke before it leaves their smokestacks. In addition, the coal industry and the U.S. government have cooperated to develop technologies that can remove impurities from coal or that can make coal more energy efficient, which reduces the amount of coal that is burned per unit of useful energy produced.

Equipment intended mainly to reduce SO ₂, NOx, and particulate matter can also be used to reduce mercury emissions from some types of coal. Scientists are also working on new ways to reduce mercury emissions from coal-burning power plants.

Research is underway to address emissions of carbon dioxide from coal combustion. One method is carbon capture, which separates CO ₂ from emissions sources and recovers it in a concentrated stream. The CO ₂ can then be injected underground for permanent storage or ( sequestration).

Reuse and recycling can also reduce the environmental effects of coal production and use. Land that was previously used for coal mining can be reclaimed and used for airports, landfills, and golf courses. Waste products captured by scrubbers can be used to produce products such as cement and synthetic gypsum for wallboard.

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Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.

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What is natural gas?

Natural gas is a fossil energy source that formed deep beneath the earth's surface. Natural gas contains many different compounds. The largest component of natural gas is methane, a compound with one carbon atom and four hydrogen atoms (CH ₄). Natural gas also contains smaller amounts of natural gas liquids (NGLs; which are also hydrocarbon gas liquids), and nonhydrocarbon gases, such as carbon dioxide and water vapor. We use natural gas as a fuel and to make materials and chemicals.

How did natural gas form?

Millions to hundreds of millions of years ago and over long periods of time, the remains of plants and animals (such as diatoms) built up in thick layers on the earth's surface and ocean floors, sometimes mixed with sand, silt, and calcium carbonate. Over time, these layers were buried under sand, silt, and rock. Pressure and heat changed some of this carbon and hydrogen-rich material into coal, some into oil (petroleum), and some into natural gas.

In some places, natural gas leaking into the air from cracks in the earth can be ignited by lightning or a fire. When people first saw this burning natural gas, they experimented with it and learned they could use it for heat and light.

Where is natural gas found?

As natural gas formed over time, it moved into large cracks and spaces between layers of overlying rock. The natural gas found in these types of formations is sometimes called conventional natural gas. In other places, natural gas occurs in the tiny pores (spaces) within some formations of shale, sandstone, and other types of sedimentary rock. This natural gas is referred to as shale gas or tight gas, and it is sometimes called unconventional natural gas. Natural gas also occurs with deposits of crude oil, and this natural gas is called associated natural gas. Natural gas deposits are found on land and some are offshore and deep under the ocean floor. A type of natural gas found in coal deposits is called coalbed methane.

How do we find natural gas?

The search for natural gas begins with geologists who study the structure and processes of the earth. They locate the types of geologic formations that are likely to contain natural gas deposits.

Geologists often use seismic surveys on land and in the ocean to find the right places to drill natural gas and oil wells. Seismic surveys create and measure seismic waves in the earth to get information on the geology of rock formations. Seismic surveys on land may use a thumper truck, which has a vibrating pad that pounds the ground to create seismic waves in the underlying rock. Sometimes small amounts of explosives are used. Seismic surveys conducted in the ocean use blasts of sound that create sonic waves to explore the geology beneath the ocean floor.

If the results of seismic surveys show that a site has potential for producing natural gas, an exploratory well is drilled and tested. The results of the test provide information on the quality and quantity of natural gas in the resource.

Drilling natural gas wells and producing natural gas

If the results from a test well show that a geologic formation has enough natural gas to produce and make a profit, one or more production (or development) wells are drilled. Natural gas wells can be drilled vertically and horizontally into natural gas-bearing formations. In conventional natural gas deposits, the natural gas generally flows easily up through wells to the surface.

In the United States and in a few other countries, natural gas is produced from shale and other types of sedimentary rock formations by forcing water, chemicals, and sand down a well under high pressure. This process, called hydraulic fracturing or fracking, and sometimes referred to as unconventional production, breaks up the formation, releases the natural gas from the rock, and allows the natural gas to flow to and up wells to the surface. At the top of the well on the surface, natural gas is put into gathering pipelines and sent to natural gas processing plants.

Did you know?

Natural gas from natural gas or crude oil wells is treated at natural gas processing plants before it is put into natural gas pipelines.

In places where natural gas pipelines are not available to take away associated natural gas produced from oil wells, the natural gas may be reinjected into the oil-bearing formation, or it may be vented or burned (flared). Reinjecting this natural gas can help to maintain pressure in oil wells to improve oil production.

Coalbed methane can be extracted from coal deposits before or during coal mining, and it can be added to natural gas pipelines without any special treatment.

Delivery of natural gas to consumers

Delivering natural gas from natural gas and oil wells to consumers requires many infrastructure assets and processing steps, and it includes several physical transfers of custody.

Processing natural gas for transportation by pipeline

Natural gas is transported from wells through gathering pipelines to natural gas processing plants where contaminants and hydrocarbon gas liquids (HGLs) are removed so dry natural gas can be safely delivered in high-pressure, long-distance pipelines to consumers.

Natural gas processing can be complex and usually involves several processes, or stages, to remove oil, water, HGLs, and other impurities such as sulfur, helium, nitrogen, hydrogen sulfide, and carbon dioxide. The composition of the wellhead natural gas determines the number of stages and the processes required to produce pipeline-quality dry natural gas. These stages and processes may be integrated into one unit or operation, be performed in a different order or at alternative locations (lease/plant), or not be required at all.

Gas-oil-water separators: Pressure relief in a single-stage separator causes a natural separation of the liquids from the gases in the natural gas. In some cases, a multi-stage separation process is required to separate the different fluid streams.

Condensate separator: Condensates are most often removed from the natural gas stream at the wellhead with separators much like gas-oil-water separators. The natural gas flow into the separator comes directly from the wellhead. Extracted condensate is sent to storage tanks.

Dehydration: A dehydration process removes water that may cause the formation of undesirable hydrates and water condensation in pipelines.

Contaminant removal: Nonhydrocarbon gases-such as hydrogen sulfide, carbon dioxide, water vapor, helium, nitrogen, and oxygen-must also be removed from the natural gas stream. The most common removal technique is to direct the natural gas though a vessel containing an amine solution. Amines absorb hydrogen sulfide and carbon dioxide from natural gas and can be recycled and regenerated for repeated use.

Nitrogen extraction: Once the hydrogen sulfide and carbon dioxide are reduced to acceptable levels, the natural gas stream is routed to a Nitrogen Rejection Unit (NRU), where it is further dehydrated using molecular sieve beds.

Methane separation: The process of demethanizing the natural gas stream can occur as a separate operation in a natural gas processing plant or as part of the NRU operation. Cryogenic processing and absorption methods are some of the ways used to separate methane from HGL.

Fractionation: Fractionation separates the HGL into component liquids using the varying boiling points of the individual HGL. HGL from the processing plant may be sent to petrochemical plants, oil refineries, and other HGL consumers.

Pipelines move natural gas from production fields to markets

Interstate natural gas pipelines operate and transport natural gas across state borders.

Intrastate natural gas pipelines operate and transport natural gas within a state border.

Hinshaw natural gas pipelines receive natural gas from interstate pipelines and deliver it to consumers for consumption within a state border.

When natural gas arrives at the locations where it will be used (usually through large pipelines), it flows into smaller diameter pipelines called mains and then into smaller service lines that go directly to homes or buildings.

Natural gas can also be stored for times of peak demand

Demand for natural gas changes daily and seasonally, while production and pipeline imports are relatively constant in the short term. Storage of natural gas during periods of low demand helps to ensure that supplies of natural gas are available during periods of high demand. Natural gas is stored in large volumes in underground facilities and in smaller volumes in tanks above or below ground.

Depleted natural gas or oil fields-that are close to consuming areas are where most of the natural gas is stored in the United States.

Salt caverns-which provide high withdrawal and injection rates relative to their working natural gas capacity. Base natural gas requirements are relatively low. Most of the salt cavern storage facilities are in salt dome formations in the states bordering the Gulf of Mexico. Salt caverns have also been leached from bedded salt formations in states in the Midwest, Northeast, and Southwest.

Aquifers-that are converted to natural gas storage reservoirs, most notably in the Midwest, where water-bearing sedimentary rock formations are overlaid with impermeable cap rock.

An ocean-going LNG carrier

Liquefied natural gas (LNG) is natural gas that has been cooled to a liquid state, at about -260° Fahrenheit, for shipping and storage. The volume of natural gas in its liquid state is about 600 times smaller than its volume in its gaseous state in a natural gas pipeline. Natural gas liquefaction makes it possible to transport natural gas to places pipelines do not reach and to use natural gas as a transportation fuel.

LNG increases markets for natural gas

Where natural gas pipelines are not feasible or do not exist, liquefying natural gas is a way to move natural gas from where it is produced to where it is used, such as to and from the United States and other countries.

LNG export facilities receive natural gas from pipelines and liquefy the gas for transport on special ocean-going LNG ships or tankers. Most LNG is transported by tankers called LNG carriers in large, super-cooled (cryogenic) tanks. LNG is also transported in smaller containers that can be placed on ships and on trucks.

At import terminals, LNG is offloaded from ships and may be stored in cryogenic storage tanks before it is returned to its gaseous state or regasified. After regasification, the natural gas is transported in natural gas pipelines to natural gas-fired power plants, industrial facilities, and residential and commercial customers.

Did you know?

U.S. LNG imports peaked in 2007

The United States imported very small amounts of LNG until 1995, and then LNG imports generally increased each year until peaking in 2007 at about 771 billion cubic feet (Bcf). LNG imports declined in most years since 2007 mainly because of as increases in U.S. natural gas production and expansion of the U.S. natural gas pipeline network reduced the need to import natural gas.

In 2021, the United States imported about 21.59 Bcf of LNG from just two countries. This was equal to about 1% of total U.S. natural gas imports in 2021.

In 2021, U.S. LNG exports reached a record high of about 3,561 Bcf to 45 countries, and LNG exports accounted for 54% of total U.S. natural gas exports. About half of LNG exports went to five countries in 2021.

The United States now produces nearly all of the natural gas that it uses

U.S. dry natural gas production in 2020 was about 33.5 trillion cubic feet (Tcf), an average of about 91.5 billion cubic feet per day and the second-highest annual amount recorded. Most of the production increases since 2005 are the result of horizontal drilling and hydraulic fracturing techniques, notably in shale, sandstone, carbonate, and other tight geologic formations. Natural gas is produced from onshore and offshore natural gas and oil wells and from coal beds. In 2020, U.S. dry natural gas production was about 10% greater than U.S. total natural gas consumption.

Five of the 34 natural gas producing states accounted for about 69% of total U.S. dry natural gas production in 2020.

What is shale?

Shale is a sedimentary rock that formed over millions of years as layers of small rocks, silt, and clay were buried under other layers of rock. Some layers of shale and other types of rock also contain biomass material. Oil and natural gas formed from this material and was trapped in small pores in the rock. The trapped natural gas and oil can be extracted the rock layers using hydraulic fracturing or fracking. Most U.S. natural gas is now produced from shale and other tight rock formations.

Offshore natural gas production

Although most of the natural gas and oil wells in the United States are on land, some wells are drilled into the ocean floor in waters off the coast of the United States. Most of U.S. offshore natural gas production occurs in federal waters in the Gulf of Mexico, the source of about 2% of U.S. dry natural gas production in 2020.

Coalbed methane and supplemental gaseous fuels

Coalbed methane, which is found in layers or beds of coal, is added to the U.S. natural gas supply. In 2019, U.S. coalbed methane production was equal to about 3% of total U.S. dry natural gas production.

Other sources of hydrocarbon gases that are included in U.S. natural gas production and consumption include blast furnace gas, refinery still gas, biomass gas, propane-air mixtures, and a gas made from petroleum or from coal called synthetic natural gas (natural gas made from petroleum hydrocarbons or from coal). These supplemental gaseous fuels were equal to about 0.2% of U.S. natural gas consumption in 2020. The largest source of synthetic natural gas in the United States is the Great Plains Synfuels Plant in Beulah, North Dakota, where coal is converted to pipeline-quality natural gas.

Although most of the natural gas consumed in the United States is produced in the United States, the United States imports some natural gas to help supply U.S. demand. The United States also exports natural gas. Most natural gas imports and exports are by pipeline as a gas and by ship as LNG. Small amounts of natural gas are imported and exported by trucks as LNG and as compressed natural gas (CNG).

Most of U.S. natural gas imports are from Canada

In 2021, about 99% of U.S. total annual natural gas imports were from Canada and nearly all by pipelines. A small amount of CNG came by truck from Canada-0.01% of total natural gas imports. About 1% of total U.S. natural gas imports came as LNG, of which 99% were from Trinidad and Tobago. U.S. natural gas imports are generally highest in winter when imports help meet increases in natural gas demand for heating.

Did you know?

Natural gas imports peaked in 2007

Total annual imports of natural gas generally declined since 2007, mainly because increases in U.S. natural gas production reduced the need for imports. Total annual imports peaked in 2007 at about 5 trillion cubic feet (Tcf). In 2021, total annual U.S. natural gas imports were 2.81 Tcf (7.29 Bcf/d).

Natural gas exports reached a record high in 2021

Until 2000, the United States exported small volumes of natural gas and mostly by pipeline to Mexico and Canada. In 2021, total annual U.S. natural gas exports were 6.65 Tcf-the highest on record, and the United States has been an annual net exporter of natural gas since 2017.

About 46% of the total U.S. natural gas exports in 2021 were by pipeline, of which 70% went to Mexico and 30% went to Canada.

TThe United States used about 30.28 trillion cubic feet (Tcf) of natural gas in 2021, the equivalent of about 31.35 quadrillion British thermal units (Btu) and 32% of U.S. primary energy consumption.

How natural gas is used in the United States

Most U.S. natural gas use is for heating and generating electricity, but some consuming sectors have other uses for natural gas.

The electric power sector uses natural gas to generate electricity. In 2021, the electric power sector accounted for about 37% of total U.S. natural gas consumption, and natural gas was the source of about 32% of the U.S. electric power sector's primary energy consumption. Most of the electricity produced by the electric power sector is sold to and used by the other U.S. consuming sectors, and that electricity use is included in each sector's total energy consumption. The other consuming sectors also use natural gas to generate electricity, and they use nearly all of this electricity themselves.

The industrial sector uses natural gas as a fuel for process heating, in combined heat and power systems, and as a raw material (feedstock) to produce chemicals, fertilizer, and hydrogen. In 2021, the industrial sector accounted for about 33% of total U.S. natural gas consumption, and natural gas was the source of about 34% of the U.S. industrial sector's total energy consumption.

The residential sector uses natural gas to heat buildings and water, to cook, and to dry clothes. About half of the homes in the United States use natural gas for these purposes. In 2021, the residential sector accounted for about 15% of total U.S. natural gas consumption, and natural gas was the source of about 23% of the U.S. residential sector's total energy consumption.

The commercial sector uses natural gas to heat buildings and water, to operate refrigeration and cooling equipment, to cook, to dry clothes, and to provide outdoor lighting. Some consumers in the commercial sector also use natural gas as a fuel in combined heat and power systems. In 2021, the commercial sector accounted for about 11% of total U.S. natural gas consumption, and natural gas was the source of about 19% of the U.S. commercial sector's total energy consumption.

The transportation sector uses natural gas as a fuel to operate compressors that move natural gas through pipelines and as a vehicle fuel in the form of compressed natural gas and liquefied natural gas. Nearly all vehicles that use natural gas as a fuel are in government and private vehicle fleets. In 2021, the transportation sector accounted for about 3% of total U.S. natural gas consumption. Natural gas was the source of about 4% of the U.S. transportation sector's total energy consumption in 2021, of which 94% was for natural gas pipeline and distribution operations.

Where natural gas is used

Natural gas is used throughout the United States, but five states accounted for about 39% of total U.S. natural gas consumption in 2021.

Natural gas has many qualities that make it an efficient, relatively clean burning, and economical energy source. However, the production and use of natural gas have some environmental and safety issues to consider.

Natural gas is a relatively clean burning fossil fuel

Burning natural gas for energy results in fewer emissions of nearly all types of air pollutants and carbon dioxide (CO ₂) than burning coal or petroleum products to produce an equal amount of energy. About 117 pounds of carbon dioxide are produced per million British thermal units (MMBtu) equivalent of natural gas compared with more than 200 pounds of CO ₂ per MMBtu of coal and more than 160 pounds per MMBtu of distillate fuel oil. The clean burning properties of natural gas have contributed to increased natural gas use for electricity generation and as a transportation fuel for fleet vehicles in the United States.

Natural gas is mainly methane-a strong greenhouse gas

Some natural gas leaks into the atmosphere from oil and natural gas wells, storage tanks, pipelines, and processing plants. The U.S. Environmental Protection Agency estimates that in 2019, methane emissions from natural gas and petroleum systems and from abandoned oil and natural gas wells were the source of about 29% of total U.S. methane emissions and about 3% of total U.S. greenhouse gas emissions (based on carbon-dioxide equivalent). The oil and natural gas industry takes steps to prevent natural gas leaks.

Natural gas exploration, drilling, and production affects the environment

When geologists explore for natural gas deposits on land, they may disturb vegetation and soil with their vehicles. Drilling a natural gas well on land may require clearing and leveling an area around the well site. Well drilling activities produce air pollution and may disturb people, wildlife, and water resources. Laying pipelines that transport natural gas from wells usually requires clearing land to bury the pipe. Natural gas production can also produce large volumes of contaminated water. This water requires proper handling, storage, and treatment so that it does not pollute land and other waters. Natural gas wells and pipelines often have engines to run equipment and compressors, which produce air pollutants and noise.

In areas where natural gas is produced at oil wells but is not economical to transport for sale or contains high concentrations of hydrogen sulfide (a toxic gas), it is burned (flared) at well sites. Natural gas flaring produces CO ₂, carbon monoxide, sulfur dioxide, nitrogen oxides, and many other compounds, depending on the chemical composition of the natural gas and on how well the natural gas burns in the flare. However, flaring is safer than releasing natural gas into the air and results in lower overall greenhouse gas emissions because CO ₂ is not as strong a greenhouse gas as methane.

Did you know?

Advances in drilling and production technologies have positive and negative effects on the environment

New drilling and natural gas recovery technologies reduce the land area that is disturbed to develop oil and gas resources. Horizontal and directional drilling techniques make it possible to produce more natural gas from a single well than in the past, so fewer wells are needed to develop a natural gas field.

The fracturing of wells requires large amounts of water. In some areas of the country, significant use of water for fracking may affect aquatic habitats and the availability of water for other uses.

If mismanaged, hydraulic fracturing fluid-which may contain potentially hazardous chemicals-could be released through spills, leaks, faulty well construction, or other exposure pathways. These releases could pollute surrounding areas.

Hydraulic fracturing produces large amounts of wastewater at the surface, which may contain dissolved chemicals and other contaminants that require proper treatment before disposal or reuse.

According to the U.S. Geological Survey, hydraulic fracturing "...causes small earthquakes, but they are almost always too small to be a safety concern. In addition to natural gas, fracking fluids and formation waters are returned to the surface. These wastewaters are frequently disposed of by injection into deep wells. The injection of wastewater into the subsurface can cause earthquakes that are large enough to be felt and may cause damage."

Natural gas could be released to the atmosphere during and after well drilling, and the amount of these releases are under investigation.

Natural gas production, transportation, distribution, and storage require strict safety regulations and standards

Because a natural gas leak could cause an explosion, there are strict government regulations and industry standards to ensure the safe transportation, storage, distribution, and use of natural gas. Because processed natural gas has no odor, natural gas companies add a strong, rotten egg-like smelling substance called mercaptan to natural gas so that people can smell leaks.

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Natural gas is a fossil energy source that formed deep beneath the earth's surface. Natural gas contains many different compounds. The largest component of natural gas is methane, a compound with one carbon atom and four hydrogen atoms (CH 4).

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What is crude oil and what are petroleum products?

We call crude oil and petroleum fossil fuels because they are mixtures of hydrocarbons that formed from the remains of animals and plants (diatoms) that lived millions of years ago in oceans, lakes, and swamps before dinosaurs roamed the earth. Over millions of years, the remains of these animals and plants were covered by layers of sand, silt, and rock. Heat and pressure from these layers turned the remains into what we now call crude oil or petroleum. Petroleum means rock oil or oil from the earth. Crude oil is found in large underground deposits, in tiny spaces within sedimentary rocks, and near the surface in tar (or oil) sands. Petroleum products are made from crude oil and other hydrocarbons contained in natural gas. Petroleum products can also be made from coal, natural gas, and biomass.

Diatoms magnified under a microscope.

Source: Image used by permission from Micrographia

The United States is one of the largest crude oil producing countries

About 100 countries produce crude oil. The United States was the top crude oil producing country in 2018 through 2022. U.S. oil refineries obtain crude oil produced in the United States and in other countries.

Where is U.S. crude oil produced?

Crude oil is produced in 32 U.S. states and in U.S. coastal waters. In 2022, five states combined accounted for about 72% of total U.S. crude oil production.

In 2022, about 14.5% of U.S. crude oil was produced from wells located offshore in the federally administered waters of the Gulf of Mexico and about 0.1% was produced in federal waters off the coast of California.

Although U.S. crude oil production went down in most years between 1985 and 2008, annual oil production went up in nearly every year from 2009 through 2019, reaching the highest amount on record in 2019. Less expensive ways of drilling for and producing crude oil helped to increase production, especially in Texas, North Dakota, Oklahoma, New Mexico, and Colorado. U.S crude oil production declined in 2020 and 2021 mainly because of the effects of the COVID-19 pandemic on the economy.

Many countries produce crude oil

In 2022, 98 countries produced about 80.75 million barrels of crude oil and five countries combined accounted for about 52% of the total.

What is offshore?

The coastlines of the United States are not the actual borders of the United States. The U.S. border is actually 200 miles away from the coastline. This area around the country is called the Exclusive Economic Zone (EEZ).

In 1983, President Ronald Reagan claimed the EEZ in the name of the United States. In 1994, all countries were granted an EEZ of 200 miles from their coastlines under the International Law of the Sea.

The ocean floor extends from the coast into the ocean on a continental shelf that gradually descends to a sharp drop, called the continental slope. The width of the U.S. continental shelf varies from 10 miles to 250 miles (16 kilometers to 400 kilometers). The water on the continental shelf is relatively shallow, rarely more than 500 feet to 650 feet (150 meters to 200 meters) deep. The continental shelf drops off at the continental slope, ending in abyssal plains that are 2 miles to 3 miles (3 kilometers to 5 kilometers) below sea level. Many of the plains are flat, while others have jagged mountain ridges, deep canyons, and valleys. The tops of some of these mountain ridges form islands where they extend above the water.

Several federal government agencies manage the natural resources in the EEZ. The U.S. Department of the Interior's Bureau of Ocean Energy Management and Bureau of Safety and Environmental Enforcement manage the development of offshore energy resources by private companies that lease areas for energy development from the federal government. These companies pay royalties to the government on the energy resources they produce from the leased areas in the ocean. Most states control the 3-mile area that extends off of their coasts, but Florida, Texas, and some other states control the waters for as much as 9 miles to 12 miles off of their coasts.

Most of the energy the United States gets from the ocean is oil and natural gas from wells drilled on the ocean floor. Other energy sources are under development offshore. America's first offshore wind energy project, the Block Island Wind Farm off the coast of Rhode Island, became operational in December 2016. Other wind energy projects are under consideration in several other areas off the Atlantic coast. Wave energy, tidal energy, ocean thermal energy conversion, and methane hydrates are other potential ocean energy sources.

Read about Energy Ant's visit to an offshore rig.

After crude oil is removed from the ground, it is sent to an oil refinery where different parts of the crude oil are separated into useable petroleum products. These petroleum products include gasoline, distillates such as diesel fuel and heating oil, jet fuel, waxes, lubricating oils, and tar (asphalt) and feedstocks (raw materials) for making chemicals.

What is a refinery?

Petroleum refineries convert crude oil and other liquids into many petroleum products that people use every day. U.S. refineries produce about 45 gallons of petroleum products from a 42-gallon barrel of crude oil because of refinery processing gain. This increase in volume is similar to what happens to popcorn when it is popped. A corn kernel is smaller and heavier than a popped kernel. The types and amounts of products produced varies from month-to-month and year-to-year as refineries change production to meet demand for petroleum products and to make the most profit.

Most refineries focus on producing transportation fuels. On average, U.S. refineries produce, from a 42-gallon barrel of crude oil, about 19 to 20 gallons of motor gasoline, 11 to 12 gallons of distillate fuel, most of which is sold as diesel fuel, and 4 gallons of jet fuel. More than a dozen other petroleum products are also produced in refineries. Petroleum refineries produce liquids the petrochemical industry uses to make a variety of chemicals and plastics.

Refineries operate 24/7

A refinery runs 24 hours a day, 365 days a year and requires a large number of employees. A refinery can occupy as much land as several hundred football fields.

How crude oil is refined into petroleum products

Petroleum refineries change crude oil into petroleum products for use as fuels for transportation, heating, paving roads, and generating electricity and as feedstocks for making chemicals.

Separation

Modern separation involves piping crude oil through hot furnaces. The resulting liquids and vapors are discharged into distillation units. All refineries have atmospheric distillation units, while more complex refineries may have vacuum distillation units.

Inside the distillation units, the liquids and vapors separate into petroleum components called fractions according to their boiling points. Heavy fractions are on the bottom and light fractions are on the top.

The lightest fractions, including gasoline and liquefied refinery gases, vaporize and rise to the top of the distillation tower, where they condense back to liquids.

Medium weight liquids, including kerosene and distillates, stay in the middle of the distillation tower.

Heavier liquids, called gas oils, separate lower down in the distillation tower, while the heaviest fractions with the highest boiling points settle at the bottom of the tower.

Conversion

After distillation, heavy, lower-value distillation fractions can be processed further into lighter, higher-value products such as gasoline. This is where fractions from the distillation units are transformed into streams (intermediate components) that eventually become finished products.

The most widely used conversion method is called cracking because it uses heat, pressure, catalysts, and sometimes hydrogen to crack heavy hydrocarbon molecules into lighter ones. A cracking unit consists of one or more tall, thick-walled, rocket-shaped reactors and a network of furnaces, heat exchangers, and other vessels. Complex refineries may have one or more types of crackers, including fluid catalytic cracking units and hydrocracking/hydrocracker units.

Cracking is not the only form of crude oil conversion. Other refinery processes rearrange molecules to add value rather than splitting molecules.

Alkylation, for example, makes gasoline components by combining some of the gaseous byproducts of cracking. The process, which essentially is cracking in reverse, takes place in a series of large, horizontal vessels and tall, skinny towers.

Reforming uses heat, moderate pressure, and catalysts to turn naphtha, a light, relatively low-value fraction, into high-octane gasoline components.

Treatment

The finishing touches occur during the final treatment. To make gasoline, refinery technicians carefully combine a variety of streams from the processing units. Octane level, vapor pressure ratings, and other special considerations determine the gasoline blend.

Storage

Both incoming crude oil and the outgoing final products are stored temporarily in large tanks on a tank farm near the refinery. Pipelines, trains, and trucks carry the final products from the storage tanks to other locations across the country.

How does oil affect the environment?

Although petroleum products make life easier, finding, producing, and moving crude oil may have negative effects on the environment. Advances in oil exploration, production, and transportation technologies and enforcement of safety and environmental laws and regulations help to avoid and reduce these effects.

Technology helps reduce the effects of drilling for and producing oil

Exploring and drilling for oil may disturb land and marine ecosystems. Seismic techniques used to explore for oil under the ocean floor may harm fish and marine mammals. Drilling an oil well on land often requires clearing an area of vegetation. However, technologies that significantly increase the efficiency of exploration and drilling activities also reduce effects on the environment. Satellites, global positioning systems, remote sensing devices, and 3-D and 4-D seismic technologies make it possible to discover oil reserves while drilling fewer exploratory wells. Mobile and smaller slimhole drilling rigs reduce the size of the area that drilling activities affect. The use of horizontal and directional drilling makes it possible for a single well to produce oil from a much larger area, which reduces the number of wells necessary to develop an oil resource.

Hydraulic fracturing

Hydraulic fracturing, or fracking, is a way to produce oil from shale and other tight underground rock layers. Fracking has helped the United States to increase oil production and reduce oil imports a lot in recent years. However, this method has effects on the environment. Fracturing rock uses large amounts of water and may use chemicals that could be harmful to humans and animals. Faulty well construction and improper handling may result in leaks and spills of fracking liquids. In some areas of the country, large amounts of water used for oil production may affect the availability of water for other uses, including for the plants and animals that live in and close to nearby rivers and streams.

Hydraulic fracturing may also produce large amounts of wastewater from fracked wells that contains harmful compounds. Because treating the wastewater can be difficult and expensive, in some places it is pumped (injected) deep underground. Unfortunately, this disposal method may cause earthquakes that are large enough to damage buildings.

Oil spills

Most oil spills happen because of accidents at oil wells or on the pipelines, ships, trains, and trucks that move oil from wells to refineries. Oil spills contaminate soil and water and may cause devastating explosions and fires. The federal government and industry work to reduce the potential for accidents and spills and to clean up spills when they occur.

After the Exxon Valdez oil spill in Prince William Sound, Alaska, in 1989, the U.S. Congress passed the Oil Pollution Act of 1990, which requires all new oil tankers built for use between U.S. ports to have a full double hull. In 1992, the International Maritime Organization also established double-hull standards for new oil tankers in the International Convention for the Prevention of Pollution from Ships (MARPOL). The amount of oil spilled from ships declined a lot during the 1990s partly because of these double-hull standards.

After the Deep Horizon drilling rig explosion and oil spill in the Gulf of Mexico in 2010, the U.S. government and the oil industry reviewed drilling technologies, procedures, and regulations to help avoid similar accidents in the future. The U.S. government also replaced the Minerals Management Service (MMS), which administered offshore oil and natural gas leases, with the Bureau of Ocean Energy Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE) to provide better oversight and enforcement of environmental regulations for offshore energy development.

In response to several major accidents involving trains carrying crude oil, the U.S. Department of Transportation and the Federal Railroad Administration set new standards for railroad tank cars, braking controls, and train speed limits to reduce the chances for railroad accidents and oil spills.

Restoring old well sites and creating artificial reefs

When oil and natural gas wells become uneconomic, they should be plugged and sealed and the area around the well restored. These procedures are designed to properly seal off subsurface rock formations and to remediate (restore) well sites to their original condition. Wells that are not properly plugged and abandoned can remain a possible hazard, potentially leaking fluids and gases and interfering with future surface development.

Some old offshore oil rigs are tipped over and left on the sea floor in a Rigs-to-Reefs program. Within a year after a rig is toppled, barnacles, coral, sponges, clams, and other sea creatures cover the rig. These artificial reefs attract fish and other marine life, and they increase fish populations and recreational fishing and diving opportunities.

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We call crude oil and petroleum fossil fuels because they are mixtures of hydrocarbons that formed from the remains of animals and plants (diatoms) that lived millions of years ago in oceans, lakes, and swamps before dinosaurs roamed the earth. Over millions of years, the remains of these animals and plants were covered by layers of sand, silt, and rock.

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Energy from moving air

Wind is caused by uneven heating of the earth's surface by the sun. Because the earth's surface is made up of different types of land and water, it absorbs the sun's heat at different rates. One example of this uneven heating is the daily wind cycle.

The daily wind cycle

During the day, air above the land heats up faster than air over water. Warm air over land expands and rises, and heavier, cooler air rushes in to take its place, creating wind. At night, the winds are reversed because air cools more rapidly over land than it does over water.

In the same way, the atmospheric winds that circle the earth are created because the land near the earth's equator is hotter than the land near the North Pole and the South Pole.

Wind energy for electricity generation

Today, wind energy is mainly used to generate electricity. Water-pumping windmills were once used throughout the United States and some still operate on farms and ranches, mainly to supply water for livestock.

How wind turbines work

Wind turbines use blades to collect the wind's kinetic energy. Wind flows over the blades creating lift (similar to the effect on airplane wings), which causes the blades to turn. The blades are connected to a drive shaft that turns an electric generator, which produces the electricity.

Electricity generation with wind

Total annual U.S. electricity generation from wind energy increased from about 6 billion kilowatthours (kWh) in 2000 to about 435 billion kWh in 2022. In 2022, wind turbines were the source of about 10.2% of total U.S. utility-scale electricity generation. Utility scale includes facilities with at least one megawatt (1,000 kilowatts) of electricity generation capacity

New technologies have decreased the cost of producing electricity from wind, and growth in wind power has been encouraged by government and industry incentives.

Wind power plants require careful planning

Operating a wind power plant is more complex than simply erecting wind turbines in a windy area. Wind power plant owners must carefully plan where to position wind turbines and must consider how fast and how often the wind blows at the site.

Good places for wind turbines are where the annual average wind speed is at least 9 miles per hour (mph)-or 4 meters per second (m/s)-for small wind turbines and 13 mph (5.8 m/s) for utility-scale turbines. Favorable sites include the tops of smooth, rounded hills; open plains and water; and mountain gaps that funnel and intensify wind. Wind resources are generally more favorable for electricity generation at higher elevations above the earth's surface. Large wind turbines are placed on towers that range from about 500 feet to as much as 900 feet tall.

Wind speeds are not the same across the country

Wind energy resources vary hourly and seasonally throughout the United States. For example, in Tehachapi, California, where numerous wind turbines are located, the wind blows more frequently from April through October than it does in the winter, and the wind is usually strongest in the afternoon. These fluctuations are a result of the extreme heat of the Mojave Desert during summer months. As the hot air over the desert rises, the cooler, denser air above the Pacific Ocean rushes through the Tehachapi mountain pass to take its place. In Montana, strong winter winds channeled through Rocky Mountain valleys create more intense winds during the winter.

Fortunately, the seasonal variations in wind speeds in California and Montana match the electricity demands of consumers in those states. In California, people use more electricity in the afternoon and during the summer. In Montana, people use more electricity, in general, during the winter.

Locations of U.S. wind power projects

In 2022, 42 states had utility-scale wind power projects, which together produced about 10% (435 billion kilowatthours [kWh]) of total U.S. utility-scale electricity generation. ¹ The five states with the most electricity generation from wind in 2022 were Texas, Iowa, Oklahoma, Kansas, and Illinois. These states combined produced about 57% of total U.S. wind electricity generation in 2022

International wind power

World wind electricity generation has also increased substantially in recent years. In 1990, 16 countries generated a total of about 3.6 billion kWh of wind electricity. In 2010, 105 countries generated about 340 billion kWh, and in 2020, 129 countries (includes Puerto Rico) generated about 1,597 billion kWh of wind electricity

Offshore wind power

The waters off the coasts of the United States have significant potential for electricity generation from wind energy. There are currently two operating U.S. offshore wind energy projects: the Block Island wind farm off the coast of Rhode Island, with 30 megawatts (MW) of electricity generation capacity, and the Coastal Virginia Offshore Wind pilot project with 12 MW electricity generation capacity. As of December 2022, wind project developers reported plans for about 7,500 MW of nameplate wind electricity generation capacity in waters off the coasts of Maryland, Massachusetts, New Jersey, Rhode Island, and Virgina, and about 20 MW in Ohio state waters on Lake Erie. European countries and China lead the world in offshore wind electric generation capacity. Many other countries have and are developing offshore wind energy projects.

Horizontal-axis turbines

Vertical-axis turbines

The size of wind turbines varies widely. The length of the blades is the biggest factor in determining the amount of electricity a wind turbine can generate. Small wind turbines that can power a single home may have an electricity generating capacity of 10 kilowatts (kW). The largest wind turbines in operation have electricity generating capacities of around 15,000 kW, and larger turbines are in development. Large turbines are often grouped together to create wind power plants, or wind farms, that provide power to electricity grids.

Horizontal-axis turbines are similar to propeller airplane engines

Horizontal-axis turbines have blades like airplane propellers, and they commonly have three blades. The largest horizontal-axis turbines are as tall as 20-story buildings and have blades more than 100 feet long. Taller turbines with longer blades generate more electricity. Nearly all of the wind turbines currently in use are horizontal-axis turbines.

Vertical-axis turbines look like egg beaters

Vertical-axis turbines have blades that are attached to the top and the bottom of a vertical rotor. The most common type of vertical-axis turbine-the Darrieus wind turbine, named after the French engineer Georges Darrieus who patented the design in 1931-looks like a giant, two-bladed egg beater. Some versions of the vertical-axis turbine are 100 feet tall and 50 feet wide. Very few vertical-axis wind turbines are in use today because they do not perform as well as horizontal-axis turbines.

Wind power plants, or wind farms, produce electricity

Wind power plants, or wind farms, are clusters of wind turbines that produce large amounts of electricity. A wind farm usually has many turbines scattered over a large area. One of the United States' largest wind farms is the Horse Hollow Wind Energy Center in Texas, which at the end of 2021, had 422 wind turbines spread over about 47,000 acres. The project has a combined electricity generating capacity of about 735 megawatts (or 735,000 kilowatts).

People have been using wind energy for thousands of years

People used wind energy to propel boats along the Nile River as early as 5,000 BC. By 200 BC, simple wind-powered water pumps were used in China, and windmills with woven-reed blades were grinding grain in Persia and the Middle East.

New ways to use wind energy eventually spread around the world. By the 11th century, people in the Middle East were using windpumps and windmills extensively for food production. Merchants and the Crusaders brought wind technology to Europe. The Dutch developed large windpumps to drain lakes and marshes in the Rhine River Delta. Immigrants from Europe eventually took wind energy technology to the Western Hemisphere.

American colonists used windmills to grind grain, to pump water, and to cut wood at sawmills. Homesteaders and ranchers installed thousands of windpumps as they settled the western United States. In the late 1800s and early 1900s, small wind-electric generators (turbines) were also widely used.

When power lines were built to transmit electricity to rural areas in the 1930s, wind pump and small turbine use began to decline. However, some ranches still use windpumps to supply water for livestock. Small wind turbines are becoming more common again, mainly to supply electricity in remote and rural areas.

Wind energy use expanded in the wake of oil shortages and environmental concerns

The oil shortages of the 1970s changed the energy environment for the United States and the world. The oil shortages created an interest in developing ways to use alternative energy sources, such as wind energy, to generate electricity. The U.S. federal government supported research and development of large wind turbines. In the early 1980s, thousands of wind turbines were installed in California, largely because of federal and state policies that encouraged the use of renewable energy sources.

In the 1990s and 2000s, the U.S. federal government established incentives to use renewable energy sources in response to a renewed concern for the environment. The federal government also provided research and development funding to help reduce the cost of wind turbines and offered tax and investment incentives for wind power projects. In addition, state governments enacted new requirements for electricity generation from renewable sources, and electric power marketers and utilities began to offer electricity generated from wind and other renewable energy sources (sometimes called green power) to their customers. These policies and programs resulted in an increase in the number of wind turbines and in the amount of electricity generated from wind energy.

The share of total U.S. electricity generation from wind energy has grown from less than 1% in 1990 to about 10.2% in 2022. Financial and other incentives for electricity generation with wind energy have resulted in a large expansion of wind energy use in the United States and Europe. China has invested heavily in wind energy and is now the world's largest wind electricity generator. In 1990, 16 countries generated a total of about 3.6 billion kWh of wind electricity. In 2021, at least 128 countries (including Puerto Rico) generated about 1,808 billion kWh of wind electricity.

Wind is an emissions-free source of energy

Wind is a renewable energy source. Overall, using wind to produce energy has fewer effects on the environment than many other energy sources. Wind turbines do not release emissions that can pollute the air or water (with rare exceptions), and they do not require water for cooling. Wind turbines may also reduce the amount of electricity generation from fossil fuels, which results in lower total air pollution and carbon dioxide emissions.

An individual wind turbine has a relatively small physical footprint. Groups of wind turbines, sometimes called wind farms, are located on open land, on mountain ridges, or offshore in lakes or the ocean.

Wind turbines have effects on the environment

Modern wind turbines can be very large machines, and they may visually affect the landscape. A small number of wind turbines have also caught fire, and some have leaked lubricating fluids, but these occurrences are rare. Some people do not like the sound that wind turbine blades make as they turn in the wind. Some types of wind turbines and wind projects cause bird and bat deaths. These deaths may contribute to declines in the population of species also affected by other human-related impacts. The wind energy industry and the U.S. government are researching ways to reduce the effect of wind turbines on birds and bats.

Most wind power projects on land require service roads that add to the physical effects on the environment. Producing the metals and other materials used to make wind turbine components has impacts on the environment, and fossil fuels may have been used to produce the materials. Although most of the materials used to make wind turbines can be reused or recycled, turbine blades, as most are currently constructed, cannot be recycled. Researchers at the National Renewable Energy Laboratory (NREL) established an approach to manufacturing wind turbine blades, employing a thermoplastic resin system. These thermoplastic resins enable a manufacturing process that allows wind turbine blades to be recycled at their end of life and also reduces the energy required to manufacture blades.

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Wind is caused by uneven heating of the earth's surface by the sun. Because the earth's surface is made up of different types of land and water, it absorbs the sun's heat at different rates. One example of this uneven heating is the daily wind cycle.

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Energy from the sun

The sun has produced energy for billions of years and is the ultimate source for all of the energy sources and fuels that we use today. People have used the sun's rays (solar radiation) for thousands of years for warmth and to dry meat, fruit, and grains. Over time, people developed technologies to collect solar energy for heat and to convert it into electricity.

Collecting and using solar thermal (heat) energy

An example of an early solar energy collection device is the solar oven (a box for collecting and absorbing sunlight). In the 1830s, British astronomer John Herschel used a solar oven to cook food during an expedition to Africa. People now use many different technologies for collecting and converting solar radiation into heat energy for a many uses.

Water for use in homes, buildings, or swimming pools

The inside of homes, greenhouses, and other buildings

Fluids to high temperatures in solar thermal power plants

Solar photovoltaic systems convert sunlight into electricity

Solar photovoltaic (PV) devices, or solar cells, change sunlight directly into electricity. Small PV cells can power calculators, watches, and other small electronic devices. Arrangements of many solar cells in PV panels and arrangements of multiple PV panels in PV arrays can produce electricity for an entire house. Some PV power plants have large arrays that cover many acres to produce electricity for thousands of homes.

Solar energy has benefits and some limitations

Solar energy systems do not produce air pollutants or carbon dioxide.

Solar energy systems on buildings have minimal effects on the environment.

The amount of sunlight that arrives at the earth's surface is not constant. The amount of sunlight varies depending on location, time of day, season of the year, and weather conditions.

The amount of sunlight reaching a square foot of the earth's surface is relatively small, so a large surface area is necessary to absorb or collect a useful amount of energy.

Solar energy is sunshine

Sunshine is radiant energy from the sun. The amount of solar radiation, or solar energy, that the earth receives each day is many times greater than the total amount of all energy that people consume each day. Use of solar energy, especially for electricity generation, has increased a lot in the United States and around the world in the past 30 years.

Latitude, climate, and weather patterns are major factors that affect insolation -the amount of solar radiation received on a given surface area during a specific amount of time. Locations nearer the equator and in arid climates generally receive higher amounts of insolation than other locations. Clouds, dust, volcanic ash, and pollution in the atmosphere affect insolation levels at the surface. Buildings, trees, and mountains may shade a location during different times of the day in different months of the year. Seasonal (monthly) variations in solar resources increase with increasing distance from the earth's equator.

The type of solar collector also determines the type of solar radiation and level of insolation that a solar collector receives. Concentrating solar collector systems, such as those used in solar thermal-electric power plants, require direct solar radiation, which is generally greater in arid regions with few cloudy days. Flat-plate solar thermal and photovoltaic (PV) collectors are able to use global solar radiation, which includes diffuse (scattered) and direct solar radiation. Learn more about solar radiation.

Solar thermal collectors

Low-temperature solar thermal collectors absorb the sun's heat energy to heat water for washing and bathing or for swimming pools, or to heat air inside buildings.

Concentrating collectors

Concentrating solar energy technologies use mirrors to reflect and concentrate sunlight onto receivers that absorb solar energy and convert it to heat. We can use this thermal energy for heating buildings or to produce electricity with a steam turbine or a heat engine that drives a generator.

Photovoltaic systems

Photovoltaic (PV) cells convert sunlight directly into electricity. PV systems can range from systems that provide tiny amounts of electricity for watches and calculators to systems that provide the amount of electricity that hundreds or thousands of homes use. Millions of houses and buildings around the world have PV systems on their roofs and there are many large PV power plants.

Use of solar energy

The U.S. Energy Information Administration (EIA) estimates that total solar energy use in the United States increased from about 0.06 trillion British thermal units (Btu) in 1984 to about 1,870 trillion Btu in 2022. Solar electricity generation accounted for about 97% of total solar energy use in 2022 and direct use of solar energy for space and water heating accounted for about 3%.

Total U.S. solar electricity generation increased from about 5 million kWh in 1984 (nearly all from utility-scale, solar thermal-electric power plants) to about 204 billion kWh in 2022. In 2022, utility-scale PV power plants accounted for 70% of total solar electricity generation, small-scale PV systems accounted for 29%, and utility-scale solar thermal-electric power plants accounted for 1%. Utility-scale power plants have at least 1,000 kilowatts (kW) (or one megawatt [MW]) of electricity generation capacity. Small-scale PV systems have less than one MW generation capacity.

According to EIA's International Energy Statistics, total world solar electricity generation grew from 0.4 billion kWh in 1990 to about 1.306 billion (about 1.3 trillion) kWh in 2021. The top five producers of solar electricity and their percentage shares of world total solar electricity generation in 2021 were:

Photovoltaic cells convert sunlight into electricity

A photovoltaic (PV) cell, commonly called a solar cell, is a nonmechanical device that converts sunlight directly into electricity. Some PV cells can convert artificial light into electricity.

Photons carry solar energy

Sunlight is composed of photons, or particles of solar energy. These photons contain varying amounts of energy that correspond to the different wavelengths of the solar spectrum.

A PV cell is made of semiconductor material. When photons strike a PV cell, they may reflect off the cell, pass through the cell, or be absorbed by the semiconductor material. Only the absorbed photons provide energy to generate electricity. When the semiconductor material absorbs enough sunlight (solar energy), electrons are dislodged from the material's atoms. Special treatment of the material surface during manufacturing makes the front surface of the cell more receptive to the dislodged, or free, electrons so that the electrons naturally migrate to the surface of the cell.

The flow of electricity

The movement of electrons, each carrying a negative charge, toward the front surface of the cell creates an imbalance of electrical charge between the cell's front and back surfaces. This imbalance, in turn, creates a voltage potential like the negative and positive terminals of a battery. Electrical conductors on the cell absorb the electrons. When the conductors are connected in an electrical circuit to an external load, such as a battery, electricity flows in the circuit.

The efficiency of photovoltaic systems varies by the type of photovoltaic technology

The efficiency at which PV cells convert sunlight to electricity varies by the type of cell material and technology. The efficiency of PV modules averaged less than 10% in the mid-1980s, increased to around 15% by 2015, and is now approaching 20% for state-of-the art modules. Experimental PV cells and PV cells for space satellites are nearly 50% efficient.

How photovoltaic systems operate

The PV cell is the basic building block of a PV system. Individual cells can vary in size from about 0.5 inches to about 4 inches across. However, one cell only produces 1 or 2 Watts, which is only enough electricity for small uses, such as for powering calculators or wristwatches.

PV cells are electrically connected in a packaged, weather-tight PV module or panel. PV modules vary in size and in the amount of electricity they can produce. PV module electricity generating capacity increases with the number of cells in the module or in the surface area of the module. PV modules can be connected in groups to form a PV array. A PV array can be composed of two or hundreds of PV modules. The number of PV modules connected in a PV array determines the total amount of electricity the array can generate.

Photovoltaic cells generate direct current (DC) electricity. This DC electricity can be used to charge batteries that, in turn, power devices that use direct current electricity. Nearly all electricity is supplied as alternating current (AC) in electric power lines. Devices called inverters are used on PV modules or in arrays to convert the DC electricity to AC electricity.

PV cells and modules will produce the largest amount of electricity when they are directly facing the sun. PV modules and arrays can use tracking systems that move the modules to constantly face the sun, but these systems are expensive and are mostly used in large PV power plants. Most PV systems on buildings have modules in a fixed position with the modules facing directly south (in the northern hemisphere-directly north in the southern hemisphere). Learn more about PV collector tilt angles and PV collector tracking systems.

Did you know?

Applications of photovoltaic systems

The smallest photovoltaic systems power calculators and wristwatches. Larger systems can provide electricity to pump water, to power communications equipment, to supply electricity for a single home or business, or to form large arrays that supply electricity to thousands of electricity consumers.

PV systems can supply electricity in locations where electricity distribution systems (power lines) do not exist, and they can also supply electricity to an electric power grid.

PV arrays can be installed quickly and can be any size.

The environmental effects of PV systems located on buildings is minimal.

History of photovoltaics

The first practical PV cell was developed in 1954 by Bell Telephone researchers. Beginning in the late 1950s, PV cells were used to power U.S. space satellites. By the late 1970s, PV panels were providing electricity in remote, or off-grid, locations that did not have electric power lines. Since 2004, most of the PV panels installed in the United States have been in grid-connected systems on homes, buildings, and central-station power facilities. Technical advances, lower costs for PV systems, and financial incentives and government policies have helped to greatly expand PV use since the mid-1990s. Hundreds of thousands of grid-connected PV systems are now installed in the United States.

EIA estimates that electricity generated at utility-scale PV power plants increased from 6 million kilowatthours (kWh) in 2004 to 143 billion kWh in 2022. Utility-scale power plants have at least 1,000 kilowatts (or one megawatt) of electricity generating capacity. EIA estimates that 59 billion kWh were generated by small-scale grid-connected PV systems in 2022, up from 11 billion kWh in 2014. Small-scale PV systems are systems that have less than 1,000 kilowatts of electricity generation capacity. Most small-scale PV systems are located on buildings and are sometimes called rooftop PV systems.

Solar thermal power systems use concentrated solar energy

Solar thermal power (electricity) generation systems collect and concentrate sunlight to produce the high temperature heat needed to generate electricity. All solar thermal power systems have solar energy collectors with two main components: reflectors (mirrors) that capture and focus sunlight onto a receiver. In most types of systems, a heat-transfer fluid is heated and circulated in the receiver and used to produce steam. The steam is converted into mechanical energy in a turbine, which powers a generator to produce electricity. Solar thermal power systems have tracking systems that keep sunlight focused onto the receiver during the day as the sun changes position in the sky.

Solar thermal power systems may also have a thermal energy storage system component that allows the solar collector system to heat an energy storage system during the day, and the heat from the storage system is used to produce electricity in the evening or during cloudy weather. Solar thermal power plants may also be hybrid systems that use other fuels (usually natural gas) to supplement energy from the sun during periods of low solar radiation.

Types of concentrating solar thermal power plants

Linear concentrating systems

Linear concentrating systems collect the sun's energy using long, rectangular, curved (U-shaped) mirrors. The mirrors focus sunlight onto receivers (tubes) that run the length of the mirrors. The concentrated sunlight heats a fluid flowing through the tubes. The fluid is sent to a heat exchanger to boil water in a conventional steam-turbine generator to produce electricity. There are two major types of linear concentrator systems: parabolic trough systems, where receiver tubes are positioned along the focal line of each parabolic mirror, and linear Fresnel reflector systems, where one receiver tube is above several mirrors to allow the mirrors greater mobility in tracking the sun.

A linear concentrating collector power plant has a large number, or field, of collectors in parallel rows with a north-south orientation so that the mirrors track the sun from east to west and concentrate sunlight continuously onto the receiver tubes during the day.

Parabolic troughs

Parabolic trough power plant

A parabolic trough collector has a long parabolic (curved-shaped) reflector that focuses the sun's rays on a receiver pipe located at the focus of the parabola. The collector moves to focus sunlight on the receiver as the sun moves through the sky during the day.

Because of its parabolic shape, a trough can focus the sunlight from 30 times to 100 times its normal intensity (concentration ratio) on the receiver pipe, located along the focal line of the trough, achieving operating temperatures higher than 750°F.

Parabolic trough linear concentrating systems are used in one of the longest operating solar thermal power facilities in the world, the Solar Energy Generating System (SEGS) located in the Mojave Desert in California. The facility has had nine separate plants over time, with the first plant in the system, SEGS I, operating from 1984 to 2015, and the second, SEGS II, operating from 1985 to 2015. SEGS III-VII (3-7), each with net summer electric generation capacities of 36 megawatts (MW), came online in 1986, 1987, and 1988. SEGS VIII (8) and IX (9), each with a net summer electric generation capacity of 88 MW, began operation in 1989 and 1990, respectively. SEGS 3, 4, 5, 6, 7, and 8 all ceased operation in 2021, leaving only SEGS 9 in operation as of December 31, 2021.

Solana Generating Station: a 296 MW project in Gila Bend, Arizona

Mojave Solar Project: a 275 MW project in Barstow, California

Genesis Solar Energy Project: a 250 MW project in Blythe, California

Nevada Solar One: a 69 MW plant near Boulder City, Nevada

Linear Fresnel reflectors

Linear Fresnel reflector (LFR) systems are similar to parabolic trough systems in that mirrors (reflectors) concentrate sunlight onto a receiver located above the mirrors. These reflectors use the Fresnel lens effect, which allows for a concentrating mirror with a large aperture and short focal length. These systems are capable of concentrating the sun's energy to about 30 times its normal intensity. Compact linear Fresnel reflector (CLFR)-also referred to as a concentrating linear Fresnel reflector-are a type of LFR technology with multiple absorbers within the vicinity of the mirrors. Multiple receivers allow the mirrors to change their position so they do not shade other reflectors. This improves system efficiency and reduces costs. A demonstration CLFR solar power plant was built near Bakersfield, California, in 2008, but it is currently not operating.

Solar power towers

A solar power tower system uses a large field of flat, sun-tracking mirrors called heliostats to reflect and focus sunlight onto a receiver on the top of a tower. Sunlight can be concentrated as much as 1,500 times. Some power towers use water as the heat-transfer fluid. Advanced designs are experimenting with molten nitrate salt because of its superior heat transfer and energy storage capabilities. The thermal energy-storage allows the system to produce electricity during cloudy weather or at night.

Ivanpah Solar Power Facility: a facility with three separate collector fields and towers with a combined net summer electric generation capacity of 393 MW in Ivanpah Dry Lake, California

Crescent Dunes Solar Energy Project: Crescent Dunes Solar Energy Project: a 110 MW one-tower facility with an energy storage component in Tonapah, Nevada

Solar dish/engines

Solar dish/engine systems use a mirrored dish similar to a very large satellite dish. To reduce costs, the mirrored dish usually has many small flat mirrors formed into a dish shape. The dish-shaped surface directs and focuses sunlight onto a thermal receiver, which absorbs and collects the heat and transfers it to an engine generator. The most common type of heat engine used in dish/engine systems is the Stirling engine. This system uses the fluid heated by the receiver to move pistons and create mechanical power. The mechanical power runs a generator or alternator to produce electricity.

Solar dish/engine systems always point straight at the sun and concentrate solar energy at the focal point of the dish. A solar dish's concentration ratio is much higher than linear concentrating systems, and it has a working fluid temperature higher than 1,380°F. The power-generating equipment of a solar dish can be placed at the focal point of the dish, making it well suited for remote locations, or the energy may be collected from many dishes and converted into electricity at a central point.

There are no utility-scale solar dish/engine projects in commercial operation in the United States.

Heating with the sun's energy

People use solar thermal energy to heat water and air. The two general types of solar heating systems are passive systems and active systems.

Passive solar space heating happens when the sun shines through the windows of a building and warms the interior. Building designs that use passive solar heating usually have south-facing windows that allow the sun to shine on solar heat-absorbing walls or floors during the day in the winter. The absorbed solar energy heats the building by natural radiation and convection at night. Window overhangs or shades block the sun from entering the windows during the summer to keep the building cool.

Active solar heating systems use a collector and a fluid that absorbs solar radiation. Fans or pumps circulate air or heat-absorbing liquids through collectors and then transfer the heated fluid directly to a room or to a heat storage system. Active solar water heating systems usually have a tank for storing solar heated water.

Solar collectors are either nonconcentrating or concentrating

Nonconcentrating collectors-The collector area (the area that intercepts the solar radiation) is the same as the absorber area (the area absorbing the radiation). Solar systems for heating water or air usually have nonconcentrating collectors. Flat-plate collectors are the most common type of nonconcentrating collectors for water and space heating in buildings and are used when temperatures lower than 200°F are sufficient.

A flat metal plate that intercepts and absorbs solar energy

A transparent cover that allows solar energy to pass through the cover and reduces heat loss from the absorber

A layer of insulation on the back of the absorber to reduce heat loss

Solar water heating collectors have metal tubes attached to the absorber. A heat-transfer fluid is pumped through the absorber tubes to remove heat from the absorber and transfer the heat to water in a storage tank. Solar systems for heating swimming pool water in warm climates usually do not have covers or insulation for the absorber, and pool water is circulated from the pool through the collectors and back to the pool.

Solar air heating systems use fans to move air through flat-plate collectors and into the interior of buildings.

Concentrating collectors -The area intercepting the solar radiation is greater, sometimes hundreds of times greater, than the absorber area. The collector focuses, or concentrates, solar energy onto an absorber. The collector usually moves so that it keeps sunlight focused on the absorber. Solar thermal power plants use concentrating solar collector systems because they can produce high temperature heat.

Solar energy systems/power plants do not produce air pollution, water pollution, or greenhouse gases. Using solar energy can have a positive, indirect effect on the environment when solar energy replaces or reduces the use of other energy sources that have larger effects on the environment.

Some toxic materials and chemicals are used to make the photovoltaic (PV) cells that convert sunlight into electricity. Some solar thermal systems use potentially hazardous fluids to transfer heat. Leaks of these materials could be harmful to the environment. U.S. environmental laws regulate the use and disposal of these types of materials.

As with any type of power plant, large solar power plants can affect the environment near their locations. Clearing land for construction and the placement of the power plant may have long-term effects on the habitats of native plants and animals. Some solar power plants may require water for cleaning solar collectors and concentrators or for cooling turbine generators. Using large volumes of ground water or surface water in some arid locations may affect the ecosystems that depend on these water resources. In addition, the beam of concentrated sunlight a solar power tower creates can kill birds and insects that fly into the beam.

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The sun has produced energy for billions of years and is the ultimate source for all of the energy sources and fuels that we use today. People have used the sun's rays (solar radiation) for thousands of years for warmth and to dry meat, fruit, and grains.

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Hydropower is energy in moving water

People have a long history of using the force of water flowing in streams and rivers to produce mechanical energy. Hydropower was one of the first sources of energy used for electricity generation and is usually the largest single renewable energy source of annual electricity generation in the United States.

n 2022, hydroelectricity accounted for about 6.2% of total U.S. utility-scale electricity generation and 28.7% of total utility-scale renewable electricity generation. ¹ Hydroelectricity generation varies annually, and it's share of total U.S. electricity generation generally decreased from the 1950's through 2020, mainly because of increases in electricity generation from other sources. Hydroelectricity's percentage share of total annual U.S. electricity generation in 2001 through 2022 averaged about 6.7%.

Hydropower relies on the water cycle

1. Solar energy heats water on the surface of rivers, lakes, and oceans, which causes the water to evaporate.

2. Water vapor condenses into clouds and falls as precipitation-rain and snow.

3. Precipitation collects in streams and rivers, which empty into oceans and lakes, where it evaporates and begins the cycle again.

The amount of precipitation that drains into rivers and streams in a geographic area determines the amount of water available for producing hydropower. Seasonal and long-term changes in rain and snowfall, such as droughts, have a big effect on hydropower production.

Hydroelectric power is produced with moving water

Because the source of hydroelectric power is water, hydroelectric power plants are usually located on or near a water source. The volume of the water flow and the change in elevation (or fall) from one point to another determine the amount of available energy in moving water. In general, the greater the water flow and the higher the fall, the more electricity a hydropower plant can produce. A big river, such as the Columbia River that forms the border between Oregon and Washington, carries a great deal of energy in its flow. Water descending rapidly from a high point, such as Niagara Falls in New York, also has substantial energy in its flow.

At hydropower plants, water flows through a pipe, or penstock, then pushes against and turns blades in a turbine to spin a generator to produce electricity.

Conventional hydroelectric facilities include

Run-of-the-river systems, where the force of the river's current applies pressure on a turbine. The facilities may have a weir (a short or low dam) in the water course to divert water flow to hydro turbines.

Storage systems, where water accumulates in reservoirs created by dams on streams and rivers and is released through hydro turbines as needed to generate electricity. Most U.S. hydropower facilities have dams and storage reservoirs.

Pumped-storage hydropower facilities are a type of hydroelectric storage system where water is pumped from a water source up to a storage reservoir at a higher elevation and is released from the upper reservoir to power hydro turbines located below the upper reservoir. The electricity for pumping may be from hydroturbines or from other types of power plants including fossil fuel or nuclear power plants. They usually pump water to storage when electricity demand (or use) and prices are low and release the stored water to generate electricity when electricity demand and prices are higher. Pumped-storage hydroelectric systems generally use more electricity to pump water to the upper water storage reservoirs than they produce with the stored water.

History of hydropower

Hydropower is one of the oldest sources of energy for producing mechanical and electrical energy. Hydropower was used thousands of years ago to turn paddle wheels to help grind grain. Before steam power and electricity were available in the United States, grain and lumber mills were powered directly with hydropower. The first industrial use of hydropower to generate electricity in the United States was in 1880, when 16 brush-arc lamps were powered using a water turbine at the Wolverine Chair Factory in Grand Rapids, Michigan. The first U.S. hydroelectric power plant opened on the Fox River near Appleton, Wisconsin, on September 30, 1882. Most U.S. hydroelectricity is now produced at large dams on major rivers, and most of these hydroelectric dams were built before the mid-1970s.

Most U.S. hydroelectricity generation capacity is in the West

There are hydropower facilities in nearly every state. Most hydroelectricity is produced at large dams built by the federal government, and many of the largest hydropower dams are in the western United States.

About half of U.S. hydroelectricity generation capacity ² is in Washington, California, and Oregon. Washington has the most hydroelectric generating capacity of any state and is the site of the Grand Coulee Dam, the largest hydropower facility in the United States. New York has the largest hydroelectricity generation capacity of all states east of the Mississippi River, followed by Alabama.

In 2022, total U.S. conventional hydroelectricity net summer electricity generation capacity 79,980 megawatts (MW)-or about 80 million kilowatts.

Hydroelectricity generation varies with precipitation levels

Because hydroelectricity generation depends on precipitation, and precipitation levels vary seasonally and annually, the ranking of each state in annual hydroelectricity generation may be different from its ranking in generation capacity.

In 2022, total U.S. conventional hydroelectricity generation was equal to about 6.2% (about 262 billion kilowatthours [kWh]) of total U.S. utility-scale electricity generation

Most dams were not built for electricity generation

Only a small percentage of the dams in the United States produce electricity. Most dams were constructed for irrigation and flood control and do not have hydroelectricity generators. The U.S. Department of Energy estimated that in 2012, non-powered dams in the United States had a total of 12,000 megawatts (MW) of potential hydropower capacity.

Hydropower generators produce clean electricity, but hydropower does affect the environment

Most dams in the United States were built mainly for flood control, municipal water supply, and irrigation water. Although many of these dams have hydroelectric generators, only a small number of dams were built specifically for hydropower generation. Hydropower generators do not directly emit air pollutants. However, dams, reservoirs, and the operation of hydroelectric generators can affect the environment.

Did you know?

A dam that creates a reservoir (or a dam that diverts water to a run-of-river hydropower plant) may obstruct fish migration. A dam and reservoir can also change natural water temperatures, water chemistry, river flow characteristics, and silt loads. All of these changes can affect the ecology and the physical characteristics of the river. These changes may have negative effects on native plants and on animals in and around the river. Reservoirs may cover important natural areas, agricultural land, or archeological sites. A reservoir and the operation of the dam may also result in the relocation of people. The physical impacts of a dam and reservoir, the operation of the dam, and the use of the water can change the environment over a much larger area than the area a reservoir covers.

Manufacturing the concrete and steel in hydropower dams requires equipment that may produce emissions. If fossil fuels are the energy sources for making these materials, then the emissions from the equipment could be associated with the electricity that hydropower facilities generate. However, given the long operating lifetime of a hydropower plant (50 years to 100 years) these emissions are offset by the emissions-free hydroelectricity.

Greenhouse gases (GHG) such as carbon dioxide and methane form in natural aquatic systems and in human-made water storage reservoirs as a result of the aerobic and anaerobic decomposition of biomass in the water. The exact amounts of GHG that form in and are emitted from hydropower reservoirs is uncertain and depend on many site specific and regional factors.

Fish ladders help salmon reach their spawning grounds

Hydropower turbines kill and injure some of the fish that pass through the turbine. The U.S. Department of Energy has sponsored the research and development of hydroturbines that could reduce fish deaths to lower than 2%, in comparison with fish kills of 5% to 10% for the best existing turbines.

Many species of fish, such as salmon and shad, swim up rivers and streams from the sea to reproduce in their spawning grounds in the beds of rivers and streams. Dams can block their way. Different approaches to fixing this problem include the construction of fish ladders and elevators that help fish move around or over dams to the spawning grounds upstream.

The gravitational pull of the moon and sun along with the rotation of the earth cause the tides. In some places, tides cause water levels near the shore to vary up to 40 feet. People in Europe harnessed this movement of water to operate grain mills more than a 1,000 years ago. Today, tidal energy systems generate electricity. Producing tidal energy economically requires a tidal range of at least 10 feet.

Tidal barrages

One type of tidal energy system uses a structure similar to a dam called a barrage. The barrage is installed across an inlet of an ocean bay or lagoon that forms a tidal basin. Sluice gates on the barrage control water levels and flow rates to allow the tidal basin to fill on the incoming high tides and to empty through an electricity turbine system on the outgoing ebb tide. A two-way tidal power system generates electricity from both the incoming and outgoing tides.

A potential disadvantage of tidal power is the effect a tidal station can have on plants and animals in estuaries of the tidal basin. Tidal barrages can change the tidal level in the basin and increase turbidity (the amount of matter in suspension in the water). They can also affect navigation and recreation.

Several tidal power barrages operate around the world. The Sihwa Lake Tidal Power Station in South Korea has the largest electricity generation capacity at 254 megawatts (MW). The oldest and second-largest operating tidal power plant is in La Rance, France, with 240 MW of electricity generation capacity. The next largest tidal power plant is in Annapolis Royal in Nova Scotia, Canada, with 20 MW of electricity generation capacity. China, Russia, and South Korea all have smaller tidal power plants.

The United States does not have any tidal power plants, and it only has a few sites where tidal energy could be economical to produce. France, England, Canada, and Russia have much more potential to use tidal power.

Tidal turbines

Tidal turbines look similar to wind turbines. They can be placed on the sea floor where there is strong tidal flow. Because water is about 800 times denser than air, tidal turbines have to be much sturdier and heavier than wind turbines. Tidal turbines are more expensive to build than wind turbines but capture more energy with the same size blades. A demonstration tidal turbine project is under development in the East River of New York.

Tidal fences

A tidal fence is a type of tidal power system that has vertical axis turbines mounted in a fence or row placed on the sea bed, similar to tidal turbines. Water passing through the turbines generates electricity. As of the end of 2021, no tidal fence projects were operating.

Waves have a lot of energy

CETO underwater wave energy device

Waves form as wind blows over the surface of open water in oceans and lakes. Ocean waves contain tremendous energy. The theoretical annual energy potential of waves off the coasts of the United States is estimated to be as much as 2.64 trillion kilowatthours, which is equal to about 64% of total U.S. utility-scale electricity generation in 2021. ( Utility-scale generation is from electric generators/power plants with at least one megawatt of generation capacity.) The west coasts of the United States and Europe, and the coasts of Japan and New Zealand, have potential sites for harnessing wave energy. Many different methods and technologies for capturing and converting wave energy to electricity are under development. These methods include placing devices on or just below the surface of the water and anchoring devices to the ocean floor.

Different ways to channel the power of waves

One way to harness wave energy is to bend or focus waves into a narrow channel to increase their size and power and to spin the turbines that generate electricity. Waves can also be channeled into a catch basin or reservoir where the water flows to a turbine at a lower elevation, similar to the way a hydropower dam operates.

The U.S. Department of Energy's Marine and Hydrokinetic Technology Database provides information on marine and hydrokinetic renewable energy, in the United States and around the world.

Ocean thermal energy conversion produces energy from temperature differences in ocean waters

Ocean thermal energy conversion (OTEC) is a process or technology for producing energy by harnessing the temperature differences (thermal gradients) between ocean surface waters and deep ocean waters.

Energy from the sun heats the surface water of the ocean. In tropical regions, surface water can be much warmer than deep water. This temperature difference can be used to produce electricity and to desalinate ocean water. Ocean Thermal Energy Conversion (OTEC) systems use a temperature difference (of at least 36° Fahrenheit or 20° Celsius) to power a turbine to produce electricity. Warm surface water is pumped through an evaporator containing a working fluid. The vaporized fluid drives a turbine/generator. The vaporized fluid is turned back to a liquid in a condenser cooled with cold ocean water pumped from deeper in the ocean. OTEC systems using seawater as the working fluid can use the condensed water to produce desalinated water.

The United States became involved in OTEC research in 1974 with the establishment of the Natural Energy Laboratory of Hawaii Authority. The laboratory is one of the world's leading test facilities for OTEC technology. The laboratory operated a 250 kilowatt (kW) demonstration OTEC plant for six years in the 1990s. The United States Navy supported the development of a 105 kW demonstration OTEC plant at the laboratory site. This facility became operational in 2015 and supplies electricity to the local electricity grid.

Other larger OTEC systems are in development or planned in several countries, mostly to supply electricity and desalinated water for island communities.

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People have a long history of using the force of water flowing in streams and rivers to produce mechanical energy. Hydropower was one of the first sources of energy used for electricity generation and is usually the largest single renewable energy source of annual electricity generation in the United States.

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The journey of hydropower: How energy moves from nature to your home (short version)

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Introduction

HYDROPOWER is a clean, low cost and renewable energy source that takes an unpredictable resource - rainfall and snowpack - and turn it into a reliable source of electricity. Hydroelectric projects can support recreation, irrigation, flood control, transportation and habitat needs.

2. Turbine Blades

TURBINE BLADES are pushed by flowing water from the penstock, causing them to rotate.

THE SHAPE AND ANGLE of the turbine blades transfers the energy of falling water to rotate the shaft.

7. Substations

AT SUBSTATIONS the voltage is decreased and the power is distributed to homes and businesses.

8. Homes & Businesses

SUBSTATIONS Before reaching our home or business from substations, voltage is again decreased at transformers. As shown in the picture, transformers are often seen at the top of power poles.

10. Spillway

SPILLWAYS release water downstream that is not directed to the powerhouse to generate electricity.

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Introduction HYDROPOWER is a clean, low cost and renewable energy source that takes an unpredictable resource - rainfall and snowpack - and turn it into a reliable source of electricity. Hydroelectric projects can support recreation, irrigation, flood control, transportation and habitat needs. 2.

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Solar power 101: How does solar energy work?

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Non-renewable Energy Sources - Types of Energy for Kids

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What Is Fossil Fuel? | FOSSIL FUELS | The Dr Binocs Show | Kids Learning Video | Peekaboo Kidz

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Fossil Fuels for Kids | Learn all about fossil fuels, what they are, and where they come from

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Types of Energy for Kids - Renewable and Non-Renewable Energies

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Alliant Energy Whispering Willow Wind Farm 360-degree Tour

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fossil fuels - advantages and disadvantages

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"Our World: Solar Energy" by Adventure Academy