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Environmental impact of energy resources

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Environmental impact of energy resources

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Generation of electricity from various energy resources has extensive impact on the environment, from extracting, processing, transporting the resources and constructing and operating the power plant.

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1. The efficiency of energy transfer in using various energy resources to generate electricity depends on factors such as the amount of energy required to extract, process and transport the resources as well as the different technologies used to generate electricity from these resources.

2. The cost also depends on factors such as the availability of the resources, the cost to extract, process and transport the resources as well as the use of different technologies to generate electricity from these resources, taxes and grants by different countries on their use, and the associated costs of risk management (e.g., climate and environmental protection).

3. Reliability refers to the ability to generate an uninterrupted supply of electricity from various energy resources, to meet the demands of industry and households.

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How is electricity generated from renewable energy resources?

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How is electricity generated from renewable energy resources?

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Biofuels

Biofuels refers to organic material from plants or animals. They can also be produced from the recycling of food waste such as used cooking oil and plant pulp. One of the most common examples of biofuels is ethanol, which can be made from plants such as corn or sugarcane. Biofuels are burned in a boiler to produce high-pressure steam. This steam flows over a series of turbine blades, causing them to rotate. The rotation of the turbine blades drives a generator, producing electricity.

Wind

Wind generates electricity by turning wind turbines. The wind pushes the turbine blades, causing it to rotate. The rotation of the turbine drives a generator, producing electricity.

Tides

Unlike wind, tides are predictable and stable. Turbines are built near fast-flowing bodies of water created by the rise and fall of tides. The force of the water on the turbine blades causes it to rotate.The rotation of the turbine blades drives a generator, producing electricity.

Hydropower

Hydropower is one of the oldest renewable energy resources and has been used for thousands of years.  Hydroelectric power plants use the flow of rivers or water behind a dam to turn turbine blades. The rotation of the turbine blades drives a generator, producing electricity.

Geothermal reservoirs

Geothermal reservoirs can be found at tectonic plate boundaries near volcanic activity or deep underground. Energy in these reservoirs can be harnessed by drilling wells to pump hot water or steam. This steam flows over a series of turbine blades, causing them to rotate. The rotation of the turbine drives a generator, producing electricity.

Solar

When light is incident on certain materials, electrons are dislodged from the material's atoms, generating a small electric current. process of converting light into electricity
Photovoltaic (PV) cells are made from these materials. They convert sunlight into electricity without the need for a turbine. Individually, each cell is only capable of powering a calculator, but when combined to create solar panels, they provide much more electricity.

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Renewable energy resources are sources of energy that replenish themselves over short periods of time.

Examples of renewable energy resources

Renewable energy resources include:

biofuel

wind

tides

hydropower

geothermal reservoirs

solar

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Non-renewable energy resources include fossil fuels and nuclear fuels. Once these resources are used up, they cannot be replaced, which is a major problem for humanity as we are currently dependent on them to supply most of our energy needs.

Fossil fuels were formed within the Earth from dead plants and animals over millions of years—hence the name “fossil” fuels. Examples include coal, natural gas and crude oil.

Nuclear fuels come from radioactive elements such as uranium and plutonium which are extracted from mined ore and then refined into fuel.

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Energy cannot be created or destroyed in any process.

Although the amount of energy remains constant after a system undergoes changes, only some of it will be present in a way that is useful to us.

The remaining energy is not lost or destroyed. It is e.g., energy gets transferred to the surroundings by heating or by doing work to overcome friction.
dissipated and ends up in less useful stores (e.g., internal stores of the surroundings).

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The more energy is transferred or more work is done (in the same amount of time), the higher the power.

The shorter the time taken (to do the same amount of work or transfer the same amount of energy), the higher the power.

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Energy of a system may be in different stores.

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Energy of a system may be in different stores.

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Energy is an abstract idea. A useful way to think of energy is to imagine it as some substance, such as an orange liquid. Just like how there can be different cups to hold the orange liquid, there are different ways in which energy can be stored in a system.

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Matter in a system

The physical parts of a system are made of objects that have mass and take up space (i.e., matter). We can identify the parts of a system by making direct observations or by using tools such as a microscope.

Energy in a system

Besides its physical parts, a system also has something else that we cannot observe directly - energy. Unlike matter, energy does not have mass or take up space. It is not a physical object that we can observe. However, we can infer that a system has energy by observing the changes (e.g., in its motion, position, temperature, etc.) that take place.

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Energy transfers and stores is a pedagogical approach to teaching and learning energy. To help you understand energy through this approach, we have a set of energy manipulatives called E = mc², where E stands for e nergy, m stands for energy m ap, c² stands for energy c ards and energy c ubes.

This website contains information for the following:

1. What is in the set of energy manipulatives?

2. What is the function of each manipulative?

3. How to use the manipulatives? ​

This activity can be done in groups of 2 - 4 players.

Game Play 1

To account for the energy transfer(s) in and out of a system and the amount of energy that is in each energy store in the initial and final states of the system.

Energy map, opaque energy cards, energy counters, scenario cards

1. Choose any scenario card and place the side with scenario A facing up in the "O" of the energy map.

2. Read the scenario on the card.

3. Determine which energy store(s) is/are involved in the initial state of the system and place the energy counter(s) in the respective columns for C (chemical), E (elastic), G (gravitational), I (internal), K (kinetic) and N (nuclear). The number of counters placed in each column is arbitrary.

4. Determine whether energy is transferred into or out of the initial and final states of the system. Determine which type of energy transfer(s) is/are involved and place the energy transfer card(s) in the dotted box on the energy map. Note that energy transfer card(s) should be placed on the left dotted box for energy transferred into the system and right dotted box for energy transferred out of the system. Place the energy counter(s) on top of the energy card(s). The number of counters on each card is arbitrary.

5. Repeat (3) and (4) for the final state of the system.

6. Check the answer with scenario card B of the corresponding number. Note that the number of energy counters for each energy store and energy transfer may differ from the group's answer as the numbers are arbitrary.

1. New scenarios can be created by writing on a Post-it sticker and placing it on the "O" of the energy map.

2. To increase the challenge, each group can time themselves and scores can be given for speed and accuracy.

Game Play 2

To recreate the scenario in words based on the energy transfer(s) in and out of a system and the amount of energy that is in each energy store in the initial and final states of the system.

1. Choose any scenario card and place the side with scenario B facing up in the "O" of the energy map.

2. Lay out the energy card(s) and energy counter(s) on the energy map as shown on the scenario card.

3. Write a description of the possible scenario that would have occurred.

4. Compare the answer with another group or check with a teacher.

1. New scenarios can be created by writing on a Post-it sticker and placing it on the "O" of the energy map.

2. Scores can be given for speed, accuracy and creativity.

Energy map, energy cards, energy counters, scenario cards

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Energy transfers and stores is a pedagogical approach to teaching and learning energy. To help you understand energy through this approach, we have a set of energy manipulatives called E = mc², where E stands for e nergy, m stands for energy m ap, c² stands for energy c ards and energy c ubes.

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Ideal pendulum (assume no air resistance)

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Ideal pendulum (assume no air resistance)

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Non-ideal pendulum (in real life, pendulum swings with air resistance)

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Non-ideal pendulum (in real life, pendulum swings with air resistance)

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What affects the energy analysis of a scenario?

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What affects the energy analysis of a scenario?

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The choice of initial and final states of the system affects the analysis of a scenario.

The choice of the objects of interest in the system affects the analysis of a scenario.

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Analysis of a Scenario: Defining the Objects of Interest in the System

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Analysis of a Scenario: Defining the Objects of Interest in the System

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Watch this video to learn how the analysis of a scenario changes when the objects of interest in the system are defined differently.

1. The choice of objects of interest affects the analysis of the event in terms of the energy transfers and energy stores involved.

2. Energy can be transferred electrically through an electric current and through propagation of waves.

3. Energy is not created or destroyed in any process. The sum of the amount of energy in an object of interest at the initial state and the amount of energy that is transferred in is equal to the sum of the amount of energy that is transferred out and the amount of energy at the final state.

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Analysis of a Scenario: Defining the Initial and Final States of the System

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Analysis of a Scenario: Defining the Initial and Final States of the System

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Watch this video to learn how the analysis of a scenario changes when the initial and final states of the system are defined differently.

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How to use the LOL diagram to understand energy store and transfer

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How to use the LOL diagram to understand energy store and transfer

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Then as the stone falls back down again, it accelerates downwards due to Earth’s gravity.

Energy in the gravitational potential store is transferred mechanically back into the kinetic store again.

At the lowest point, just before the stone hits the ground, all the energy in the gravitational potential store will have been transferred back to the kinetic store.

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As the stone moves up and reach max height...

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As the stone moves up and reach max height...

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Now as the stone moves up, it will slow down until it reaches its maximum height.

At first, energy was present in the kinetic store of the stone.

As it moves upwards, the height of the stone increases and energy is transferred mechanically, from the kinetic store of the stone to its gravitational potential store.

When the stone is momentarily at rest at its maximum height, there's no energy left in its kinetic store.

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When you release stone, there remains a contact force between the elastic band and the stone.

Energy is transferred mechanically from the elastic potential store of the elastic band to the kinetic store of the stone.

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Before you launch the stone, energy is present in the elastic potential store of the band of the slingshot.

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A system can be a single object or a group of objects of interest.

When an interaction causes a system to undergo changes, energy is transferred.

The amount of energy in a system constrains what changes can happen to it.

In the physics syllabus, we typically encounter six energy stores and four pathways in which energy can be transferred within or across systems.

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Transfer of energy through the propagation of waves

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Transfer of energy through the propagation of waves

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Transfer of energy through the propagation of electromagnetic (e.g. light) and mechanical (e.g. sound) waves

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Transfer of energy through heating due to a temperature difference.

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Transfer of energy electrically by electric current

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Transfer of energy electrically by electric current

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Transfer of energy electrically by an electric current

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Transfer of energy mechanically by a force 

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Transfer of energy mechanically by a force 

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Transfer of energy mechanically by a force acting over a distance.

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6 Types of Energy Stores:

1. Kinetic store, which is associated with moving objects.

2. Gravitational potential store, which is associated with objects depending on position in a gravitational field.

3. Chemical potential store which is associated with substances that undergo chemical reactions.

4. Elastic potential store which is associated with materials which are compressed or stretched and have a tendency to restore their original shape.

5. Nuclear store which is associated with atomic nuclei whose nuclear configurations could be altered.

6. Internal store: the energy associated with the microscopic particles that make up macroscopic objects.

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Energy existing in different stores inside a system

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Energy existing in different stores inside a system

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We can think of  energy as existing in different stores inside a system. It is like how your money can be stored in different places. Some of your money could be stored in your wallet. Some could be stored in your bank account and some is stored in your money box at home.

You can move your money between these three “stores”. For example, you could take money out of your bank account or empty your money box.

But notice these two things:

1. The total amount of money that you have doesn't change until you use it to buy something. Even then, the money still exists in the world.

2. Wherever the money ends up, it's still the same quantity, whether as coins, or dollar notes. It's just in a different store. The distribution of money within each of the stores may change but the total amount of money in the world remains the same.

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Energy analysis of a simple slingshot and stone

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Energy analysis of a simple slingshot and stone

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The system here is made up of a slingshot and a stone.

The arms of the slingshot are assumed to be held in place while the elastic band is stretched. Suppose the stretched band of the slingshot has three joules of energy in its elastic potential store.

When the stone is released, energy is transferred from the elastic potential store of the elastic band to the kinetic store and gravitational potential store of the stone.

Assuming the stone does not get additional energy from the person’s hand, the maximum amount of energy of the stone is 3 joules.

With three joules of energy, we can make certain calculations and predict that the maximum vertical height of the stone is only x metres.

If you want the stone to reach a vertical height of 2X metres instead, you will need more energy.

So analysing the amount of energy available, allows us to know the possible changes that can or cannot take place.

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As a concrete illustration of the analogy, suppose you have only two dollars. With the two dollars you have, the possible interactions that could take place are limited.

You could either buy a packet of instant noodles, or a loaf of bread. Or you could buy nothing at all. But we can be very sure that you won’t end up with a bar of chocolate.

So, the amount of money you have can only determines which interactions can or cannot take place but not what actually happens.

In the same way, the amount of energy of a system determines what changes can or cannot take place but not the specific change that actually occurred.

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When an interaction causes a system to undergo changes, energy is transferred.

You can think of energy as some sort of money.

Just like the amount of money you have determines what you can and cannot do, the amount of energy determines changes can take place and what changes cannot.

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A battery recharges when electric current flows through the circuit and triggers a chemical reaction

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A car can change its speed, position and even shape when it collides with another car

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Water in a kettle can undergo a change in state when it is heated on a stove.

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Energy transfer from one store to another store, not convert from one form to another.

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Strategy for problem involving Energy analysis

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Strategy for problem involving Energy analysis

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A three-stage approach to thinking about an event can be used to separate explanations from energy analysis:
1. Observation – a description of what happens in everyday language
2. An explanation – that uses mechanisms and processes to explain what happened
3. An energy analysis – using a start and end point to compare how full different energy stores are before and after the event

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1. The most important ideas about energy is that it is conserved.

In every event and processes, there is the same total amount at the end as there was at the beginning.

2. Energy is a measure of the capacity of an object or system to do work.

Energy provides a quantitative value of the amount of work an object or system is capable of doing, under ideal conditions.

3. Energy is not a mechanism that explains how things happen.

It does not help us to understand how or why they happen.

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A system:

consists of one or more objects of interest

can undergo changes due to an interaction

a collection of interrelated parts that form a unified whole.