# data[].attributes.body
How has solar energy changed people's lives in urban areas in Chin

# data[].attributes.body
Kimberly

# data[].attributes.attachment_link.readable_text
Introduction

China's environmental crisis is one of the most pressing challenges to emerge from the country's rapid industrialization. Its economic rise, in which GDP grew on average 10 percent each year for more than a decade, has come at the expense of its environment and public health. China is the world's largest source of carbon emissions, and the air quality of many of its major cities fails to meet international health standards. Life expectancy north of the Huai River is 5.5 years lower than in the south due to air pollution ( life expectancy in China is 75.3 years, according to 2013 UN figures). Severe water contamination and scarcity have compounded land deterioration. Environmental degradation threatens to undermine the country's growth and exhausts public patience with the pace of reform. It has also bruised China's international standing and endangered domestic stability as the ruling party faces increasing scrutiny and public discontent. More recently, amid waning economic growth, leaders in Beijing appear more determined to institute changes to stem further degradation.

A History of Pollution

While China's economic boom has greatly accelerated the devastation of its land and resources, the roots of its environmental problem stretch back centuries. Dynastic leaders who consolidated territory and developed China's economy exploited natural resources in ways that contributed to famines and natural disasters, writes CFR's Elizabeth C. Economy The River Runs Black: The Environmental Challenge to China's Future. "China's current environmental situation is the result not only of policy choices made today but also of attitudes, approaches, and institutions that have evolved over centuries," Economy writes.

It wasn't until the 1972 United Nations Conference on the Human Environment that China began to develop environmental institutions. It dispatched a delegation to the conference in Stockholm, but by then the country's environment was already in dire straits.

Economic reforms in the late 1970s that encouraged development in rural industries further exacerbated the problem.

[Air pollution] mitigation has become a crucial political challenge for the country's political leadership.

Jane Nakano and Hong Yang,

Chinese leader Deng Xiaoping implemented a series of reforms that diffused authority to the provinces, creating a proliferation of township and village enterprises (TVEs). By 1997, TVEs generated almost a third of national GDP, though TVEs have since declined in relative importance to the Chinese economy. But local governments were difficult to monitor and seldom upheld environmental standards. Today, with a transitioning Chinese economy fueled by large state-owned enterprises, environmental policies remain difficult to enforce at the local level, where officials often prioritize hitting economic targets over environmental concerns. Despite the government's stated goals, actual change to environmental policies and effective implementation will require revisiting state-society and state-market relations and China's bureaucratic power structure, writes CFR's Yanzhong Huang.

China's modernization has lifted hundreds of millions out of poverty and created a booming middle class. In some ways, the country's trajectory of industrialization is not unlike those of other modernizing nations, such as the UK in the early nineteenth century. But experts say China's environmental footprint is far greater than that of any other single country.

How Bad Is It?

China is the world's largest emitter of greenhouse gases, having overtaken the United States in 2007, and was responsible for 27 percent of global emissions in 2014.

Coal is largely to blame for the degradation of air quality. China is the world's largest coal producer and accounts for about half of global consumption. Mostly burned in the north, coal provides around two-thirds of China's energy mix; however, demand for it appears to be declining. China's National Energy Agency claimed that coal use dropped to 64.2 percent of the mix in 2014, down almost two percent from 2012. This drop in coal demand also comes as China's economy is slowing, with its central bank forecasting that annual growth will only expand by 6.8 percent in 2016, down from 6.9 percent a year earlier. Still, doubts linger of China's commitment to wean itself from coal. In 2015, China's coal power plant capacity increased by 55 percent in the first six months, 155 new coal-fired plants were approved, and China admitted that it had underreported its annual coal consumption since 2000.

Industry along China's major water sources has polluted water supplies: In 2014, groundwater supplies in more than 60 percent of major cities were categorized as "bad to very bad," and more than a quarter of China's key rivers are " unfit for human contact." And lack of waste removal and proper processing has exacerbated problems. Combined with negligent farming practices, overgrazing, and the effects of climate change, the water crisis has turned much of China's arable land into desert. About 1.05 million square miles of China's landmass are undergoing desertification, affecting more than 400 million people, according to the deputy head of China's State Forestry Administration. Water scarcity, pollution, and desertification are reducing China's ability to sustain its industrial output and produce food and drinkable water for its large population.

Cost of Environmental Damage

Environmental depredations pose a serious threat to China's economic growth, costing the country roughly 3 to 10 percent of its gross national income, according to various estimates. China's Ministry of Environmental Protection calculates estimates the cost of pollution at around 1.5 trillion RMB ($227 billion), or roughly 3.5 percent of GDP, according to 2010 figures. Due to the sensitivity of the topic, the ministry only releases such figures intermittently.

Data on the toll of China's pollution on public health paint a devastating picture. Air pollution contributes to an estimated 1.2 million premature deaths in China annually. Epidemiological studies conducted since the 1980s in northern China suggest that poor air quality in Chinese cities causes significant health complications, including respiratory, cardiovascular, and cerebrovascular diseases. Pollution has also been linked to the proliferation of acute and chronic diseases; estimates suggest that around 11 percent of digestive-system cancers in China may stem from unsafe drinking water.

Recent studies have reported that emissions from China's export industries are worsening air pollution as far as the western United States. China's neighbors, including Japan and South Korea, have also expressed concern over acid rain and smog affecting their populations. Environmental ministers from the three northeast Asian countries agreed to boost cooperative efforts to curb air pollution and to protect water quality and the maritime environment in 2014.

The damage has also affected China's economic prospects as it continues to pursue extractive resources abroad, such as oil and other fossil fuels. Its economic partners, particularly in the developing world, face costly environmental burdens attached with doing business with China, write CFR's Economy and Michael Levi in By All Means Necessary, their book on China's quest for resources.

Citizen Outrage

Environmental damage has cost China dearly, but the greatest collateral damage for the ruling Communist Party has likely been growing social unrest. Demonstrations have proliferated as citizens gain awareness of the health threats and means of organized protest (often using social media). In 2013, Chen Jiping, former leading member of the party's Committee of Political and Legislative Affairs said that environmental issues are a major reason for "mass incidents" in China-unofficial gatherings of one hundred or more that range from peaceful protest to rioting. Environmental protests in rural and urban areas alike-such as those in Guangdong, Shanghai, Ningbo, and Kunming-are increasing in frequency. The number of " abrupt environmental incidents ", including protests, in 2013 rose to 712 cases, a 31 percent uptick from the previous year.

CFR's Economy points out that one of the most important changes in China's environmental protest movement has been a shift, beginning in the late 2000s, from predominantlyrural-based protests to urban-based movements. The issue has worried the top leadership, which views the unrest as a threat to the party's legitimacy. "Air pollution in China has turned into a major social problem and its mitigation has become a crucial political challenge for the country's political leadership," write Center for Strategic and International Studies's Jane Nakano and Hong Yang. Yet the government has responded to public outcries: Chinese Premier Li Keqiang declared a "war on pollution" in March 2014; in May of the same year the government strengthened the country's Environmental Protection Law for the first time in twenty-five years. Such moves reflect "a changing understanding within China about the relationship between economic development and societal wellbeing," Economy and Levi write.

The internet has played a crucial role in allowing citizens to spread information about the environment, placing additional political pressure on the government. In March 2015, Under the Dome, a TED Talk-style documentary on China's air pollution, went viral, attracting hundreds of thousands of views before internet censors blocked access, and in 2013 the discovery of thousands of dead pigs in the Huangpu river also spread rapidly online. However, experts say the jury is still out on the current government will implement meaningful reforms, which has shown more resolve in cracking down on public dissent than implementing environmental measures.

What's Being Done?

What we're seeing now is an entirely new administration with an entirely different outlook on climate change.

China is one of the biggest investors in renewables, investing nearly $90 billion in 2014 as part of its pledge to cut its carbon intensity (far outspending the United States' $51.8 billion). Some analysts have predicted that China is on track to overtake the United States as the world's leading producer of wind energy by 2016. Meanwhile, Chinese firms continue to invest in and partner with international companies to develop renewable energy technologies.

Though policy implementation has been inconsistent, the environmental NGO community has grown to push the government to stay on track. Thousands of these groups-often working with U.S. and foreign counterparts-push for transparency, investigate corruption, and head grassroots campaigns. Friends of Nature is one of its oldest; Global Village and Green Home are among other well-known NGOs. Despite state support, these organizations inevitably face constraints from government fear that their activities could catalyze democratic social change.

Despite the political reforms needed to catalyze any real change in the environmental sphere, the response to China's crisis has triggered some optimism about the future. "What we're seeing now is an entirely new administration with an entirely different outlook on climate change," writes Greenpeace East Asia's Li Shuo. China, once reluctant to take a stand on environmental issues and climate change, emerged as a leader in negotiations at the 2015 UN Climate Conference in Paris where 195 countries signed a breakthrough accord. While China deserves due credit for its ambitious efforts to curtail its own environmental crisis, Economy says it cannot be assumed that Beijing will follow through on its promises. "The proof will be on the ground -and of course, in the atmosphere."

# data[].attributes.attachment_link.description
China's environmental crisis is one of the most pressing challenges to emerge from the country's rapid industrialization. Its economic rise, in which GDP grew on average 10 percent each year for more than a decade, has come at the expense of its environment and public health.

# data[].attributes.attachment_link.readable_text
Air pollution in Beijing is emblematic of China's many environmental problems.

Credit: Hung Chung Chih / Shutterstock.com

China's environmental crises seem to arise on a scale as sweeping and epic as the vast nation itself:

Thousands of dead, bloated pigs floating down the river that supplies Shanghai with its drinking water. Air pollution in Beijing so impenetrable the U.S. Embassy's air quality measuring station can only call it "beyond index." Industrial towns where rates of cancer are so high they're known as "cancer villages."

Compounding these problems is the Chinese government's stony silence about anything that might imperil the country's economic development - including environmental regulation.

But China's increasingly restive population of 1.3 billion people is now starting to demand government action to combat the deadly plagues of pollution and disease that are stalking the 21st century's economic powerhouse. [ The 10 Most Polluted Places on Earth]

Chinese officials, however, have barely started to acknowledge the problem. In the meantime, the people of China are forced to face the following environmental catastrophes on a daily basis:

Air pollution

According to the Environmental Protection Agency's air quality scale, any pollution rating above 300 means the air is unsafe to breathe. Under these conditions, people should stay indoors with an air purifier running and remain as motionless as possible, according to U.S. Embassy Beijing guidelines.

In January alone, there were 19 days when the index in Beijing surpassed that 300 threshold, according to the Washington Post, and readings above 500 are no longer unusual. On Jan. 12, the reading reached an eye-bleeding 886, comparable to living inside a smoking lounge.

Manufacturing industries and Beijing's 5 million-plus cars all contribute to the city's crippling air pollution, but most experts primarily blame the coal-burning electrical plants that power China's breakneck economic growth.

China now burns 47 percent of the world's coal, roughly equal to the amount used by all other countries of the world combined, the New York Times reports. And Beijing is surrounded by a vast network of coal-burning power plants.

But as foul as it is, Beijing's air isn't even China's worst: That dubious honor goes to Ürümqi in the country's far west, which frequently joins other Chinese cities like Lanzhou and Linfen on lists of the world's most polluted places. [ Top 10 Ways to Destroy Earth]

Water pollution

Thousands of dead pigs floating past Shanghai, dramatic though they are, may be the least of China's water pollution worries.

In January, a chemical accident leaked benzene, a known cancer-causing agent, into a tributary of the Huangpu River (where the dead pigs were discovered). More than 20 people were hospitalized as a result, according to the Wall Street Journal, and area residents were forced to rely on fire trucks to deliver safe drinking water.

More than half of China's surface water is so polluted it cannot be treated to make it drinkable, the Economist reports, and one-quarter of it is so dangerous it can't even be used for industrial purposes.

Groundwater isn't any safer: About 40 percent of China's farmland relies on underground water for irrigation, and an estimated 90 percent is polluted, Reuters reports. About 60 percent of the groundwater beneath Chinese cities is described as "severely polluted" by the Economist.

Last December - shortly after his sister died of lung cancer at age 35 - businessman Jin Zengmin from Zhejiang province offered a 200,000-yuan ($32,000) reward to any local environmental official who would swim in a nearby river, where Jin once swam as a boy, Time.com reports. The river is now black with sludge from an upstream shoe factory.

His reward remains uncollected.

Desertification

China has a history of intensive agriculture going back millennia, so it's perhaps unsurprising that much of the nation's 3.7 million square-mile (9.6 million square kilometers) territory has been subject to deforestation.

Population pressure, the conversion of forests to farmland, and hydroelectric and other infrastructure projects have placed China's remaining forests at risk. This prompted the United Nations Environment Programme to list the country's forests as threatened and in need of protection.

Following closely on the heels of deforestation and agricultural development is desertification, the destruction of vegetative land cover that results in a landscape defined by bare soil and rock. About 1 million square miles (2.6 million sq km) of China is now under desertification - that's about one-quarter of the country's total land surface, spread across 18 provinces, according to IPS News Agency.

Blinding dust storms, mud-choked rivers and eroded topsoil are often the result of desertification. Despite recent gains in reforestation and grasslands restoration, the desert continues to expand each year by about 950 square miles (2,460 sq km), according to the World Wildlife Fund (WWF). [ Dry and Drying: Stark Images of Drought]

The resulting loss of arable land has created a generation of "eco-migrants," the Guardian reports, who are forced to leave their homelands, because their traditional agricultural lifestyle is no longer an option.

"We've made progress, but we face a daunting challenge," Liu Tuo, Chinese desertification control officer, told the Guardian. "It may take China 300 years."

Biodiversity

Closely related to deforestation and desertification is the issue of habitat loss and the resulting drop in biodiversity. As vast areas of forest are cleared for farmland, bamboo plantations, timber and fuel wood, endangered animals like pandas struggle to survive.

China's issues with species loss extend far beyond its borders: The slaughter of elephants for ivory, the killing of rhinos for their horns, and the culling of tigers for their bones (as medicine) and penises (as aphrodisiacs) have one primary source: the Chinese market.

Sharks are endangered worldwide, largely because of shark finning - the removal of dorsal fins from still-living sharks - for the Chinese delicacy known as shark fin soup.

Cancer villages

Perhaps no other issue underscores China's reckless disregard for environmental and public health more than the existence of "cancer villages," entire towns that have been written off as so polluted that simply living there is a cancer risk.

For years, individuals and groups have waged a desperate campaign to force the government to address - or even acknowledge - the high rates of stomach, liver, kidney and colon cancer in certain areas, usually adjacent to heavy industrial complexes, the BBC reports.

In Shangba, a city in southern Guangdong province, the river that flows through town changes from white to a startling shade of orange because of varying types of industrial effluent, Reuters reports. Many of the river's contaminants, like cadmium and zinc, are known to cause cancer.

"All the fish died, even chickens and ducks that drank from the river died. If you put your leg in the water, you'll get rashes and a terrible itch," He Shuncai, a 34-year-old farmer from Shangba, told Reuters. "Last year alone, six people in our village died from cancer and they were in their 30s and 40s."

In February of this year, a report from China's environment ministry noted that chemicals and heavy metals banned in other countries are found throughout China. The report went on to state that there are "some serious cases of health and social problems like the emergence of cancer villages in individual regions," marking the first official admission of the problem that has plagued the country for decades.

Population growth

China's "one-child" policy is universally acknowledged as having effectively kept the country's population in check. Nonetheless, China is home to about 1.3 billion people - over one-seventh of the planet's people live in the nation.

What's more of a concern to environmental advocates is the growing affluence of China's middle class, who are now adopting Western-style consumer patterns. While items like red meat, liquor and automobiles were once considered forbidden luxuries, more and more families are driving their car to a market to buy tenderloin beef, 120-proof baijiu liquor and other consumer goods.

The health risks associated with these kinds of purchases have not gone unnoticed: Binge drinking and alcohol-related hospitalizations have now reached "epidemic proportions," the Guardian reports, and the Chinese - who once enjoyed a relatively healthy diet and low rates of cancer - now dine on twice as much meat as Americans, consuming one-quarter of the world's supply, according to the Telegraph.

These consumer trends, multiplied across a large and heavily populated country, have a global reach that affects everything from sugar prices in Europe to climate change in Greenland: Most climate experts agree that China's industrial growth, and its dependence on coal-burning, are significant drivers of climate change, Scientific American reports.

Can China change course?

While China's traditionally obdurate government hierarchy has seemed to value economic development at any cost, including the health of its citizens and wholesale eco-destruction, there are signs of a thaw in the icy silence that shrouds much environmental action in the country.

The government's recent admission that cancer villages exist "shows that the environment ministry has acknowledged that pollution has led to people getting cancer," environmental lawyer Wang Canfa told Agence Frence-Presse. "It shows that this issue, of environmental pollution leading to health damages, has drawn attention."

Coupled with the public outcry over the thick blanket of toxic smog that covered Beijing earlier this year, there are glimmers of hope that the Chinese people may succeed in wresting some measure of control over their environment - and their lives - back from government and industry leaders.

Whether they will succeed remains to be seen.

# data[].attributes.attachment_link.description
China's environmental crises seem to arise on a scale as sweeping and epic as the vast nation itself: Thousands of dead, bloated pigs floating down the river that supplies Shanghai with its drinking water. Air pollution in Beijing so impenetrable the U.S. Embassy's air quality measuring station can only call it "beyond index."

# data[].attributes.headline
Solar And Wind Power More Expensive Than Thought

# data[].attributes.subject
Solar And Wind Power More Expensive Than Thought

# data[].attributes.attachment_link.readable_text
A new study from the Brookings Institution, a Washington think tank, argues that using solar and wind energy may be the most expensive alternatives to carbon-based electricity generation, even though they require no expenditures for fuel.

The paper, by economist Charles Frank, compares the benefits and costs of renewable energy. The benefits range from the lack of emissions to the savings in expenditures for fuels. The costs include the construction and maintenance of these plants, and the drop in power generated when winds are calm or the Sun doesn't shine.

Frank's conclusion: Wind and solar power cost far more than anyone expected.

The paper examined four kinds of carbon-free energy - solar, wind, hydroelectric and nuclear - as well as low-carbon gas generation, and compared them with generators that burn fossil fuels. It also posited a value of $50 per metric ton of reduced carbon emissions and $16 per million BTUs of gas.

Frank calculated that electricity generated by a combination of nuclear, hydro and natural gas have much greater benefits than either wind or solar energy because wind and solar generators cost more to operate even though they require no fuel.

For example, nuclear plants run at about 90 percent of capacity compared with wind turbines, which are only about 25 percent efficient, and solar plants with only 15 percent efficiency. As a result, Frank wrote, nuclear plants avoid almost four times as much CO2 per unit of capacity as wind turbines, and six times as much as solar generators.

Specifically, this means nuclear power offers a savings of more than $400,000 worth of carbon emissions per megawatt of capacity. Solar saves only $69,000 and wind saves $107,000.

Still, Frank conceded, nuclear power plants are costly to build. As an example, he cited a new plant at Hinkley Point in southwestern England, which is expected to cost $27 billion by the time it's finished. Its operating costs rise because, like all nuclear plants, it can't be covered by commercial insurance.

But like all nuclear plants, it will run 24 hours a day and so, Frank calculates, it will be only 75 percent more expensive per megawatt of energy to build and operate than a solar generator.

Into this equation, Frank included the generators powered by fossil fuels that will be needed to take up the slack for the inevitable idle periods for wind farms and solar generators. He calls them "avoided capacity costs" that wouldn't exist if the alternative energy plants hadn't been built in the first place.

Therefore, Frank wrote, it would take four wind farms or seven solar generators to replace one coal-fired plant generating similar output. Solar generation costs $189,000 to match 1 megawatt per year generated by coal, and wind power is nearly as expensive. Hydropower, he said, provides a net savings, but only a small one.

Frank's paper concluded that the winner in this comparison of zero-emission power generation is nuclear power because, despite initial costs, it is greatly efficient and operates non-stop.

By Andy Tully of Oilprice.com

# data[].attributes.attachment_link.title
Solar And Wind Power More Expensive Than Thought | OilPrice.com

# data[].attributes.attachment_link.description
A new study from the Brookings Institution, a Washington think tank, argues that using solar and wind energy may be the most expensive alternatives to carbon-based electricity generation, even though they require no expenditures for fuel. The paper, by economist Charles Frank, compares the benefits and costs of renewable energy.

# data[].attributes.headline
Solar Energy Isn’t Always as Green as You Think

# data[].attributes.subject
Solar Energy Isn’t Always as Green as You Think

# data[].attributes.attachment_link.provider_name
IEEE Spectrum: Technology, Engineering, and Science News

# data[].attributes.attachment_link.readable_text
Photo: Imaginechina/Corbis

On the Line: A factory worker in China inspects crystalline silicon photovoltaic cells.

Solar panels glimmering in the sun are an icon of all that is green. But while generating electricity through photovoltaics is indeed better for the environment than burning fossil fuels, several incidents have linked the manufacture of these shining symbols of environmental virtue to a trail of chemical pollution. And it turns out that the time it takes to compensate for the energy used and the greenhouse gases emitted in photovoltaic panel production varies substantially by technology and geography.

That's the bad news. The good news is that the industry could readily eliminate many of the damaging side effects that do exist. Indeed, pressure for it to do so is mounting, in part because, since 2008, photovoltaics manufacturing has moved from Europe, Japan, and the United States to China, Malaysia, the Philippines, and Taiwan; today nearly half the world's photovoltaics are manufactured in China. As a result, although the overall track record for the industry is good, the countries that produce the most photovoltaics today typically do the worst job of protecting the environment and their workers.

To understand exactly what the problems are, and how they might be addressed, it's helpful to know a little something about how photovoltaic panels are made. While solar energy can be generated using a variety of technologies, the vast majority of solar cells today start as quartz, the most common form of silica (silicon dioxide), which is refined into elemental silicon. There's the first problem: The quartz is extracted from mines, putting the miners at risk of one of civilization's oldest occupational hazards, the lung disease silicosis.

The initial refining turns quartz into metallurgical-grade silicon, a substance used mostly to harden steel and other metals. That happens in giant furnaces, and keeping them hot takes a lot of energy, a subject we'll return to later. Fortunately, the levels of the resulting emissions-mostly carbon dioxide and sulfur dioxide-can't do much harm to the people working at silicon refineries or to the immediate environment.

The next step, however-turning metallurgical-grade silicon into a purer form called polysilicon-creates the very toxic compound silicon tetrachloride. The refinement process involves combining hydrochloric acid with metallurgical-grade silicon to turn it into what are called trichlorosilanes. The trichlorosilanes then react with added hydrogen, producing polysilicon along with liquid silicon tetrachloride-three or four tons of silicon tetrachloride for every ton of polysilicon.

Photo: Imaginechina/AP Photo

Acid Drain: Wastewater exits a plant operated by Jinko Solar Holding Co. In 2011, hydrofluoric acid used by the company for solar-panel manufacturing contaminated river water, killing hundreds of fish and dozens of pigs.

Most manufacturers recycle this waste to make more polysilicon. Capturing silicon from silicon tetrachloride requires less energy than obtaining it from raw silica, so recycling this waste can save manufacturers money. But the reprocessing equipment can cost tens of millions of dollars. So some operations have just thrown away the by-product. If exposed to water-and that's hard to prevent if it's casually dumped-the silicon tetrachloride releases hydrochloric acid, acidifying the soil and emitting harmful fumes.

When the photovoltaics industry was smaller, the solar-cell manufacturers got their silicon from chipmakers, which rejected wafers that did not meet the computer industry's purity requirements. But the boom in photovoltaics demanded more than semiconductor-industry leftovers, and many new polysilicon refineries were built in China. Few countries at the time had stringent rules covering the storage and disposal of silicon tetrachloride waste, and China was no exception, as some Washington Post reporters discovered.

The paper's investigation, published in March 2008, profiled a Chinese polysilicon facility owned by Luoyang Zhonggui High-Technology Co., located near the Yellow River in the country's Henan province. This facility supplied polysilicon to Suntech Power Holdings, at the time the world's largest solar-cell manufacturer, as well as to several other high-profile photovoltaics companies.

The reporters found that the company was dumping silicon tetrachloride waste on neighboring fields instead of investing in equipment that could reprocess it, rendering those fields useless for growing crops and inflaming the eyes and throats of nearby residents. And the article suggested that the company was not alone in this practice.

After the publication of the Washington Post story, solar companies' stock prices fell. Investors feared the revelations would undermine an industry that relies so much on its green credentials. After all, that's what attracts most customers and draws public support for policies that foster the adoption of solar energy, such as the Residential Renewable Energy Tax Credit in the United States. Those who purchase residential solar systems can subtract 30 percent of the cost from their tax bills until the incentive expires in 2016.

To protect the industry's reputation, the manufacturers of photovoltaic panels began to inquire about the environmental practices of their polysilicon suppliers. Consequently, the situation is now improving. In 2011 China set standards requiring that companies recycle at least 98.5 percent of their silicon tetrachloride waste. These standards are easy to meet so long as factories install the proper equipment. Yet it remains to be seen how well the rules are being enforced.

This problem could completely go away in the future. Researchers at the National Renewable Energy Laboratory in Golden, Colo., are looking for ways to make polysilicon with ethanol instead of chlorine-based chemicals, thereby avoiding the creation of silicon tetrachloride altogether.

The struggle to keep photovoltaics green does not end with the production of polysilicon. Solar-cell manufacturers purify chunks of polysilicon to form bricklike ingots and then slice the ingots into wafers. Then they introduce impurities into the silicon wafers, creating the essential solar-cell architecture that produces the photovoltaic effect.

These steps all involve hazardous chemicals. For example, manufacturers rely on hydrofluoric acid to clean the wafers, remove damage that comes from sawing, and texture the surface to better collect light. Hydrofluoric acid works great for all these things, but when it touches an unprotected person, this highly corrosive liquid can destroy tissue and decalcify bones. So handling hydrofluoric acid requires extreme care, and it must be disposed of properly.

But accidents do happen and are more likely in places that have limited experience manufacturing semiconductors or that have lax environmental regulations. In August 2011, a factory in China's Zhejiang province owned by Jinko Solar Holding Co., one of the largest photovoltaic companies in the world, spilled hydrofluoric acid into the nearby Mujiaqiao River, killing hundreds of fish. And farmers working adjacent lands, who used the contaminated water to clean their animals, accidently killed dozens of pigs.

In investigating the dead pigs, Chinese authorities found levels of hydrofluoric acid in the river 10 times the permitted limit, and they presumably took these measurements long after much of the hydrofluoric acid had washed downstream. Hundreds of local residents, upset over the incident, stormed and temporarily occupied the manufacturing facility. Again, investors reacted: When major media outlets carried the news the next day, Jinko's stock price dropped by more than 40 percent, translating to nearly US $100 million in lost value.

This threat to the environment needn't continue. Researchers at Rohm & Haas Electronic Materials, a subsidiary of Dow Chemical, have identified substitutes for the hydrofluoric acid used in solar-cell manufacture. One good candidate is sodium hydroxide (NaOH). Although NaOH is itself a caustic chemical, it is easier to treat and dispose of than hydrofluoric acid and is less risky for workers. It is also easier to treat wastewater containing NaOH.

Although more than 90 percent of photovoltaic panels made today start with polysilicon, there is a newer approach: thin-film solar-cell technology. The thin-film varieties will likely grow in market share over the next decade, because they can be just as efficient as silicon-based solar cells and yet cheaper to manufacture, as they use less energy and material.

Source: Argonne National Laboratory/Fengqi You et al.

Carbon in Creation: Solar-panel manufacturers need electricity and thermal energy, and carbon emissions from their generation can vary widely with location. Panels produced in China, which relies heavily on coal for power, have a larger carbon footprint than those produced in Europe.

Makers of thin-film cells deposit layers of semiconductor material directly on a substrate of glass, metal, or plastic instead of slicing wafers from a silicon ingot. This produces less waste and completely avoids the complicated melting, drawing, and slicing used to make traditional cells. In essence, a piece of glass goes in at one end of the factory and a fully functional photovoltaic module emerges from the other.

Moving to thin-film solar cells eliminates many of the environmental and safety hazards from manufacturing, because there's no need for certain problematic chemicals-no hydrofluoric acid, no hydrochloric acid. But that does not mean you can automatically stamp a thin-film solar cell as green.

Today's dominant thin-film technologies are cadmium telluride and a more recent competitor, copper indium gallium selenide (CIGS). In the former, one semiconductor layer is made of cadmium telluride; the second is cadmium sulfide. In the latter, the primary semiconductor material is CIGS, but the second layer is typically cadmium sulfide. So each of these technologies uses compounds containing the heavy metal cadmium, which is both a carcinogen and a genotoxin, meaning that it can cause inheritable mutations.

Manufacturers like First Solar, based in Tempe, Ariz., have a strong record of protecting workers from cadmium exposures during manufacture. But there is little information about exposures to workers involved with cadmium at earlier stages in the life cycle of the metal, from the zinc mines where much of cadmium originates through the smelting process that purifies cadmium and turns it into semiconductor materials. Exposures after solar panels are discarded are also a concern. Most of the cadmium telluride that manufacturers dispose of due to damage or manufacturing defects is recycled under safe, controlled conditions. On the postconsumer end of the equation, the industry proactively set up a solar-panel collection and recycling scheme in Europe. Individual companies have also established recycling programs, such as First Solar's prefunded take-back system. But more needs to be done; not every consumer has access to a free take-back program, and indeed many consumers may not even be aware of the need to dispose of panels responsibly.

The best way to avoid exposing workers and the environment to toxic cadmium is to minimize the amount used or to use no cadmium at all. Already, two major CIGS-photovoltaic manufacturers-Avancis and Solar Frontier-are using zinc sulfide, a relatively benign material, instead of cadmium sulfide. And researchers from the University of Bristol and the University of Bath, in England; the University of California, Berkeley; and many other academic and government laboratories are trying to develop thin-film photovoltaics that do not require toxic elements like cadmium or rare elements like tellurium. First Solar has meanwhile been steadily reducing the amount of cadmium used in its solar cells.

Toxicity isn't the only concern. Making solar cells requires a lot of energy. Fortunately, because these cells generate electricity, they pay back the original investment of energy; most do so after just two years of operation, and some companies report payback times as short as six months. This " energy payback " time is not the same as the time needed to recoup a consumers financial investment in solar panels; it measures investments and payback times in terms of kilowatt-hours, not in terms of money.

Analysts also judge the impact of the energy used to make a solar panel by the amount of carbon generated in the production of that energy-a number that can vary widely. To do this, we give the energy a carbon-intensity value, usually represented as kilograms of CO ₂ emitted per kilowatt-hour generated. Places that depend largely on coal have the most carbon-intense electricity in the world: Chinese electricity is a good example, having roughly twice the carbon intensity of U.S. electricity. This fits with the results of researchers in Illinois at Argonne National Laboratory and Northwestern University. In a report published this past June, they found that the carbon footprint of photovoltaic panels made in China is indeed about double that of those manufactured in Europe.

If the photovoltaic panels made in China were installed in China, the high carbon intensity of the energy used and that of the energy saved would cancel each other out, and the time needed to counterbalance greenhouse-gas emissions during manufacture would be the same as the energy-payback time. But that's not what's been happening lately. The manufacturing is mostly located in China, and the panels are often installed in Europe or the United States. At double the carbon intensity, it takes twice as long to compensate for the greenhouse-gas emissions as it does to pay back the energy investments.

Source: Silicon Valley Toxics Coalition

The Solar Scorecard: The Silicon Valley Toxics Coalition evaluates solar-panel manufacturers on a range of environmental and worker-safety criteria. Shown here are the 10 highest-ranked companies out of 40 evaluated in the coalition's 2013 scorecard. At the top of the list is China's Trina Solar, with a score of 77 out of 100 possible points.(Update: Trina raised its score to 92 in the 2014 Solar Scorecard, with the California-based company Sunpower in second place at 88.)

Of course, if you manufacture photovoltaic panels with low-carbon electricity (for example, in a solar-powered factory) and install them in a high-carbon-intensity country, the greenhouse-gas-payback time will be lower than the energy-payback time. So perhaps someday, powering photovoltaic-panel manufacturing with wind, solar, and geothermal energy will end concerns about the carbon footprint of photovoltaics.

Water is yet another issue. Photovoltaic manufacturers use a lot of it for various purposes, including cooling, chemical processing, and air-pollution control. The biggest water waster, though, is cleaning during installation and use. Utility-scale projects in the 230- to 550-megawatt range can require up to 1.5 billion liters of water for dust control during construction and another 26 million liters annually for panel washing during operation. However, the amount of water used to produce, install, and operate photovoltaic panels is significantly lower than that needed to cool thermoelectric fossil- and fissile-power plants.

The choices investors and consumers make could, in principle, have a big influence on photovoltaic manufacturers' practices. But it's often tough to tell how these companies differ in the care they take to protect the environment. The solar industry has no formal ecolabel, like the Energy Star labels on household appliances and consumer electronics that help U.S. buyers identify energy-efficient products. And most people do not go out and purchase solar panels themselves. They hire third-party installers. So even if there were an ecolabeling scheme, it would depend on installers' willingness to choose ecofriendly products.

For now, consumers can help push manufacturers to improve their environmental and safety records by asking installers about the companies making the products they use. This, in turn, would prompt installers to ask the manufacturers for more information.

Researchers at the National Photovoltaics Environmental Research Center at Brookhaven National Laboratory in Upton, N.Y., have long been publishing studies about the possible environmental hazards of photovoltaics. Recently, formal environmental performance ratings for the solar industry have started to emerge.

Organizations such as the Center for International Earth Science Information Network are trying to establish some means of determining the environmental, health, and safety performance of manufacturers in developing countries. This group, which includes researchers from Yale and Columbia, is proposing the China Environmental Performance Index, which would operate at the provincial level to help China track progress toward environmental-policy goals.

Meanwhile, the Solar Energy Industries Association, a U.S. national trade organization, has proposed new industry guidelines in a document called the "Solar Industry Environment & Social Responsibility Commitment," aimed at preventing occupational injury and illness, preventing pollution, and reducing the natural resources used in production. The document urges companies to ask suppliers to report on manufacturing practices and any chemical and greenhouse-gas emissions.

In addition, the Silicon Valley Toxics Coalition, which rates the environmental performance of electronics companies, has surveyed and ranked photovoltaic manufacturing companies based or operating in China, Germany, Malaysia, the Philippines, and the United States. Participation is voluntary and so far includes such major manufacturers as First Solar, SolarWorld, SunPower, Suntech, Trina, and Yingli; Chinese manufacturers Trina and Yingli have consistently ranked among the world's top three most environmentally responsible companies. And Sharp, SolarWorld, and SunPower have been carefully tracking the greenhouse gases emitted and chemicals used in the manufacture of their solar panels for several years.

Such initiatives are coming none too soon. Many people today view photovoltaics as a panacea for our energy woes, given how dirty most of the alternatives are. But that does not mean we should turn a blind eye to the darker side of this technology. Indeed, we need to consider it very carefully. And just maybe, with a sustained effort by consumers, manufacturers, and researchers, the photovoltaics industry will one day be truly, not just symbolically, green.
This article originally appeared in print as "Solar's Green Dilemma." This article was updated 12 November 2014.
About the Author

Dustin Mulvaney is an assistant professor of environmental studies at San Jose State University, in California, where he concentrates on the solar-energy, biofuel, and natural-gas industries. Although he identifies himself as both a solar advocate and a solar user-he has a photovoltaic array in his yard-his research has made him mindful of the significant health risks and environmental costs of manufacturing PV panels.

# data[].attributes.attachment_link.title
Solar Energy Isn't Always as Green as You Think

# data[].attributes.attachment_link.description
Solar panels glimmering in the sun are an icon of all that is green. But while generating electricity through photovoltaics is indeed better for the environment than burning fossil fuels, several incidents have linked the manufacture of these shining symbols of environmental virtue to a trail of chemical pollution.

# data[].attributes.headline
13 Fundamental Advantages and Disadvantages of Solar Energy

# data[].attributes.subject
13 Fundamental Advantages and Disadvantages of Solar Energy

# data[].attributes.attachment_link.title
13 Fundamental Advantages and Disadvantages of Solar Energy

# data[].attributes.attachment_link.description
Advantage #1 - No green house gases The first and foremost advantage of solar energy is that, beyond panel production, it does not emit any green house gases. Solar energy is produced by conducting the sun's radiation - a process void of any smoke, gas, or other chemical by-product.

# data[].attributes.attachment_link.readable_text
It's generally assumed that it only takes a few years before solar panels have generated as much energy as it took to make them, resulting in very low greenhouse gas emissions compared to conventional grid electricity.

However, a more critical analysis shows that the cumulative energy and CO2 balance of the industry is negative, meaning that solar PV has actually increased energy use and greenhouse gas emissions instead of lowering them.

The problem is that we use and produce solar panels in the wrong places. By carefully selecting the location of both manufacturing and installation, the potential of solar power could be huge.

Picture: Jonathan Potts.

There's nothing but good news about solar energy these days. The average global price of PV panels has plummeted by more than 75% since 2008, and this trend is expected to continue in the coming years, though at a lower rate. [] According to the 2015 solar outlook by investment bank Deutsche Bank, solar systems will be at grid parity in up to 80% of the global market by the end of 2017, meaning that PV electricity will be cost-effective compared to electricity from the grid. []

Lower costs have spurred an increase in solar PV installments. According to the Renewables 2014 Global Status Report, a record of more than 39 gigawatt (GW) of solar PV capacity was added in 2013, which brings total (peak) capacity worldwide to 139 GW at the end of 2013. While this is not even enough to generate 1% of global electricity demand, the growth is impressive. Almost half of all PV capacity in operation today was added in the past two years (2012-2013). [] In 2014, an estimated 45 GW was added, bringing the total to 184 GW. [] [].

Solar PV total global capacity, 2004-2013. Source: Renewables 2014 Global Status Report.

Meanwhile, solar cells are becoming more energy efficient, and the same goes for the technology used to manufacture them. For example, the polysilicon content in solar cells -- the most energy-intensive component -- has come down to 5.5-6.0 grams per watt peak (g/wp), a number that will further decrease to 4.5-5.0 g/wp in 2017. [] Both trends have a positive effect on the sustainability of solar PV systems. According to the latest life cycle analyses, which measure the environmental impact of solar panels from production to decommission, greenhouse gas emissions have come down to around 30 grams of CO2-equivalents per kilwatt-hour of electricity generated (gCO2e/kWh), compared to 40-50 grams of CO2-equivalents ten years ago. [] []

According to these numbers, electricity generated by photovoltaic systems is 15 times less carbon-intensive than electricity generated by a natural gas plant (450 gCO2e/kWh), and at least 30 times less carbon-intensive than electricity generated by a coal plant (+1,000 gCO2e/kWh). The most-cited energy payback times (EPBT) for solar PV systems are between one and two years. It seems that photovoltaic power, around since the 1970s, is finally ready to take over the role of fossil fuels.

Manufacturing has Moved to China

Unfortunately, a critical review of the PV solar industry paints a very different picture. Many commenters attribute the plummeting cost of solar PV to more efficient manufacturing processes and scale economies. However, if we look at the graph below, we see that the decline in costs accelerates sharply from 2009 onwards. This acceleration has nothing to do with more efficient manufacturing processes or a technological breakthrough. Instead, it's the consequence of moving almost the entire PV manufacturing industry from western countries to Asian countries, where labour and energy are cheaper and where environmental restrictions are more loose.

Less than 10 years ago, almost all solar panels were produced in Europe, Japan, and the USA. In 2013, Asia accounted for 87% of global production (up from 85% in 2012), with China producing 67% of the world total (62% in 2012). Europe's share continued to fall, to 9% in 2013 (11% in 2012), while Japan's share remained at 5% and the US share was only 2.6%. []

Compared to Europe, Japan and the USA, the electric grid in China is about twice as carbon-intensive and about 50% less energy efficient. [] Because the manufacture of solar PV cells relies heavily on the use of electricity (for more than 95%) [], this means that in spite of the lower prices and the increasing efficiency, the production of solar cells has become more energy-intensive, resulting in longer energy payback times and higher greenhouse gas emissions. The geographical shift in manufacturing has made almost all life cycle analyses of solar PV panels obsolete, because they are based on a scenario of domestic manufacturing, either in Europe or in the United States.

LCA of Solar Panels Manufactured in China

We could find only one study that investigates the manufacturing of solar panels in China, and it's very recent. In 2014, a team of researchers performed a comparative life cycle analysis between domestic and overseas manufacturing scenarios, taking into account geographic diversity by utilizing localized inventory data for processes and materials. [] In the domestic manufacturing scenario, silicon PV modules (mono-si with 14% efficiency and multi-si with 13.2% efficiency) are made and installed in Spain. In the overseas manufacturing scenario, the panels are made in China and installed in Spain.

For solar panels manufactured in China, the carbon footprint and the energy payback time are almost doubled

Compared to the domestic manufacturing scenario, the carbon footprint and the energy payback time are almost doubled in the overseas manufacturing scenario. The carbon footprint of the modules made in Spain (which has a cleaner grid than the average in Europe) is 37.3 and 31.8 gCO2e/kWh for mono-si and multi-si, respectively, while the energy payback times are 1.9 and 1.6 years. However, for the modules made in China, the carbon footprint is 72.2 and 69.2 gCO2e/kWh for mono-si and multi-si, respectively, while the energy payback times are 2.4 and 2.3 years. []

At least as important as the place of manufacturing is the place of installation. Almost all LCAs -- including the one that deals with manufacturing in China -- assume a solar insolation of 1,700 kilowatt-hour per square meter per year (kWh/m2/yr), typical of Southern Europe and the southwestern USA. If solar modules manufactured in China are installed in Germany, then the carbon footprint increases to about 120 gCO2e/kWh for both mono- and multi-si -- which makes solar PV only 3.75 times less carbon-intensive than natural gas, not 15 times.

Considering that at the end of 2014, Germany had more solar PV installed than all Southern European nations combined, and twice as much as the entire United States, this number is not a worst-case scenario. It reflects the carbon intensity of most solar PV systems installed between 2009 and 2014. More critical researchers had already anticipated these results. A 2010 study refers to the 2008 consensus figure of 50 gCO2e/kWh mentioned above, and adds that "in less sunny locations, or in carbon-intensive economies, these emissions can be up to 2-4 times higher". [] Taking the more recent figure of 30 gCO2e/kWh as a starting point, which reflects improvements in solar cell and manufacturing efficiency, this would be 60-120 gCO2e/kWh, which corresponds neatly with the numbers of the 2014 study.

Solar insolation in Europe and the USA. Source: SolarGIS.

These results don't include the energy required to ship the solar panels from China to Europe. Transportation is usually ignored in LCAs of solar panels that assume domestic production, which would make comparisons difficult. Furthermore, energy requirements for transportation are very case-specific. It should also be kept in mind that these results are based on a solar PV lifespan of 30 years. This might be over-optimistic, because the relocation of manufacturing to China has been associated with a decrease in the quality of PV solar panels. [] Research has shown that the percentage of defective or under-performing PV cells has risen substantially in recent years, which could have a negative influence on the lifespan of the average solar panel, decreasing its sustainability.

Solar PV electricity remains less carbon-intensive than conventional grid electricity, even when solar cells are manufactured in China and installed in countries with relatively low solar insolation. This seems to suggest that solar PV remains a good choice no matter where the panels are produced or installed. However, if we take into account the growth of the industry, the energy and carbon balance can quickly turn negative. That's because at high growth rates, the energy and CO2 savings made by the cumulative installed capacity of solar PV systems can be cancelled out by the energy use and CO2 emissions from the production of new installed capacity. [] []

At high growth rates, the energy and CO2 savings made by the cumulative installed capacity of solar PV systems can be cancelled out by the energy use and CO2 emissions from the production of new installed capacity

A life cycle analysis that takes into account the growth rate of solar PV is called a "dynamic" life cycle analysis, as opposed to a "static" LCA, which looks only at an individual solar PV system. The two factors that determine the outcome of a dynamic life cycle analysis are the growth rate on the one hand, and the embodied energy and carbon of the PV system on the other hand. If the growth rate or the embodied energy or carbon increases, so does the "erosion" or "cannibalization" of the energy and CO2 savings made due to the production of newly installed capacity. []

For the deployment of solar PV systems to grow while remaining net greenhouse gas mitigators, they must grow at a rate slower than the inverse of their CO2 payback time. [] For example, if the average energy and CO2 payback times of a solar PV system are four years and the industry grows at a rate of 25%, no net energy is produced and no greenhouse gas emissions are offset. [] If the growth rate is higher than 25%, the aggregate of solar PV systems actually becomes a net CO2 and energy sink. In this scenario, the industry expands so fast that the energy savings and GHG emissions prevented by solar PV systems are negated to fabricate the next wave of solar PV systems. []

The CO2 Balance of Solar PV

Several studies have undertaken a dynamic life cycle analysis of renewable energy technologies. The results -- which are valid for the period between 1998 and 2008 -- are very sobering for those that have put their hopes on the carbon mitigation potential of solar PV power. A 2009 paper, which takes into account the geographical distribution of global solar PV installations, sets the maximum sustainable annual growth rate at 23%, while the actual average annual growth rate of solar PV between 1998 and 2008 was 40%. [] []

This means that the net CO2 balance of solar PV was negative for the period 1998-2008. Solar PV power was growing too fast to be sustainable, and the aggregate of solar panels actually increased GHG emissions and energy use. According to the paper, the net CO2 emissions of the solar PV industry during those 10 years accounted to 800,000 tonnes of CO2. [] These figures take into account the fact that, as a consequence of a cleaner grid and better manufacturing processes, the production of solar PV panels becomes more energy efficient and less carbon-intensive over time.

Between 2009 and 2014, solar PV grew four times too fast to be sustainable

The sustainability of solar PV has further deteriorated since 2008. On the one hand, industry growth rates have accelerated. Solar PV grew on average by 59% per year between 2008 and 2014, compared to an annual growth rate of 40% between 1998 and 2008 . [] On the other hand, manufacturing has become more carbon-intensive. For its calculations of the CO2 balance in 2008, the study discussed above considers the carbon intensity of production worldwide to be 500 gCO2e/kWh. In 2013, with 87% of the production in Asia, this number had risen to about 950 gCO2e/kWh, which halves the maximum sustainable growth rate to about 12%.

If we also take into account the changes in geographic distribution of solar panels, with an increasing percentage installed in regions with higher solar insolation, the maximum sustainable growth rate increases to about 16%. [] Although more recent research is not available, it's obvious that the CO2 emissions of the solar PV industry have further increased during the period 2009-2014. If we would consider all solar panels in the world as one large energy generating plant, it would not have generated any net energy or CO2-savings.

The Solution: Rethink the Manufacture and Use of Solar PV

Obviously, the net CO2 balance of solar PV could be improved by limiting the growth of the industry, but that would be undesirable. If we want solar PV to become important, it has to grow fast. Therefore, it's much more interesting to focus on lowering the embodied energy of solar PV power systems, which automatically results in higher sustainable growth rates. The shorter the energy and CO2 payback times, the faster the industry can grow without becoming a net producer of CO2.

Annual net CO2 balance of the crystalline silicon PV industry at different growth rates for different combinations of countries of production and installation. Source: Briner 2009.

Embodied energy and CO2 will gradually decrease because of technological advances such as higher solar cell efficiencies and more efficient manufacturing techniques, and also as a consequence of the recycling of solar panels, which is not yet a reality. However, what matters most is where solar panels are manufactured, and where they are installed. The location of production and installation is a decisive factor because there are three parameters in a life cycle analysis that are location dependent: the carbon intensity of the electricity used in production, the carbon intensity of the displaced electricity mix at the place of installation, and the solar insolation in the place of installation. []

By carefully selecting the locations for production and installation we could improve the sustainability of solar PV power in a spectacular way. For PV modules produced in countries with low-carbon energy grids -- such as France, Norway, Canada or Belgium -- and installed in countries with high insolation and carbon-intensive grids -- such as China, India, the Middle East or Australia -- greenhouse gas emissions can be as low as 6-9 gCO2/kWh of generated electricity. [] [] [] That's 13 to 20 times less CO2 per kWh than solar PV cells manufactured in China and installed in Germany. []

Sustainable growth rates of 300-460% are possible when PV modules are produced in countries with low-carbon energy grids and installed in countries with high insolation and carbon-intensive grids

This would allow sustainable growth rates of up to 300-460%, far above what's even necessary. If solar PV would grow on average at a rate of 100% per year, it would take less than 10 years to meet today's electricity's demand. If it would grow at the 16% maximum sustainable growth rate we calculated above, meeting today's electricity demand would take until 2045 -- with no net CO2 savings. By that time, according to the forecasts, total global electricity demand will have more than doubled. []

Of course, producing and installing solar panels in the right places implies international cooperation and a sound economic system, none of which exist. Manufacturing solar panels in Europe or the USA would also make them more expensive again, while many countries with the right conditions for solar don't have the money to install them in large amounts.

CO2 mitigation potential for crystalline silicon PV modules produced in China and installed in different countries. Source: Briner 2009.

An alternative solution is using on-site generation from renewables to meet a greater proportion of the electricity demand of PV manufacturing facilities -- which can also happen in a country with a carbon-intensive grid. For example, if the electricity for the manufacturing of solar cells would be supplied by other solar cells, then the greenhouse emissions of solar PV systems could be reduced by 50-70%, depending on where they are produced (Europe or the USA). [] In China, this decrease in CO2 emissions would even be greater.

In yet another scenario, we could dedicate nuclear plants exclusively to the manufacture of solar cells. Because nuclear is less carbon-intensive than PV solar, this sounds like the fastest, cheapest and easiest way to start producing a massive amount of solar cells without raising energy use and greenhouse emissions. But don't underestimate the task ahead. A 1 GW nuclear power plant can produce about 11 million square metres of solar panels per year, which corresponds to 1.66 GWp of solar power (based on the often cited average number of 150 w/m2). We would have needed 24 nuclear plants -- or 1 in 20 atomic plants worldwide -- working full-time to produce the solar panels manufactured in 2013. []

What About Storage?

Why does the production of solar PV requires so much energy? Because the low power density -- several orders of magnitude below fossil fuels -- and the intermittency of solar power require a much larger energy infrastructure than fossil fuels do. It's important to realize that the intermittency of solar power is not taken into account in our analysis. Solar power is not always available, which means that we need a backup-source of power or a storage system to jump in when the need is there. This component is usually not considered in LCAs of solar PV, even though it has a large influence on the sustainability of solar power.

Storage is no longer an academic question because several manufacturers -- most notably Tesla -- are pushing lithium-ion battery storage as an alternative for a grid-connected solar PV system. Lithium-ion batteries are more compact and technically superior to the lead-acid batteries commonly used in off-grid solar systems. Furthermore, the disincentivation of grid-connected solar systems in a growing number of countries makes off-grid systems more attractive.

In the next article, we investigate the sustainability of a PV-system with a lithium-ion battery. Meanwhile, enjoy the sun and stay tuned.

Kris De Decker (edited by Aaron Vansintjan)

# data[].attributes.attachment_link.description
It's generally assumed that it only takes a few years before solar panels have generated as much energy as it took to make them, resulting in very low greenhouse gas emissions compared to conventional grid electricity.