In the film Planet of the Humans, producer and director Jeff Gibbs and executive producer Michael Moore take aim at renewable energy technologies and the environmental organizations such as 350.org and the Sierra Club that promote them. The film’s premise is that green tech is not so green and that turning to this technology as a cure for climate change would be worse than the disease.
Scientists and environmental activists have already disputed many of the assertions in the movie, which was released on YouTube on April 21. One commonly cited problem is that the film’s renewable energy claims are often a decade out of date — ancient in green tech years — and misleading. Here’s a closer look at five of those claims.
Making solar cells is not environmentally friendly.
As the film notes, traditional photovoltaic solar cells are made with high-grade, extremely pure silicon, gleaned from quartz mined from mountains and then melted at very, very high temperatures. That takes a lot of energy, which may be generated from coal or other fossil fuels, therefore releasing climate-warming carbon emissions (SN: 2/27/08).
Solar cell manufacturing also creates environmentally harmful by-products, such as liquid silicon tetrachloride. Tetrachloride can be recycled, but if released into the environment, it can react with water to form hydrochloric acid. However, researchers are investigating alternatives to using chlorine-based compounds during manufacturing, which would eliminate tetrachloride as a by-product.
Meanwhile, solar cell technology is advancing rapidly. Thin-film solar cells involve layers of light-absorbing semiconductors such as cadmium telluride or copper indium gallium selenide that are deposited on glass, metal or plastic. This technology uses only a fraction of the silicon needed to make the thick silicon wafers of a standard photovoltaic cell. Thin-film cells also eliminate the use of dangerous hydrofluoric acid to clean the wafers.
Although industry uses some thin-film cells, they are generally too pricey to be appealing for widespread use. But there’s a promising thin-film prospect on the horizon, which uses a coating of a light-absorbing material called perovskite (SN: 7/26/17). As Nature reported in 2019, right now the race is on to make perovskite solar cells cheap enough to be commercially viable.
Solar cells are really inefficient.
In one memorable scene, Gibbs visits the Cedar Street Solar Array in Lansing, Mich. A representative from the Lansing Board of Water and Light tells him that the array’s solar cells have less than 8 percent efficiency (the amount of generated energy relative to the incoming solar energy). The utility has roughly 800 solar panels in the array, which can power maybe 10 houses for a year, he says.
That plant, however, was installed in 2008, which is multiple generations ago in solar cell technology time. Efficiencies for standard photovoltaics are much higher now, hovering close to 20 percent. Perovskite solar cells push that efficiency even higher, up to 25 percent. And by creating “tandem” solar cells that layer perovskite on top of silicon, manufacturers can maximize the ability of the cells to absorb light in different parts of the spectrum, increasing the efficiency still further.
Planet of the Humans questions the value of renewable energy technologies, suggesting that, for example, manufacturing the solar cells for a power plant releases more fossil fuel emissions than the plant’s carbon-free solar power would save.LeoPatrizi/E+/Getty Images
Solar cells and wind turbines have such short life spans that manufacturing replacements uses up more fossil fuels than the renewable energies save.
Planet of the Humans suggests that the carbon emissions released from the energy involved in manufacturing new parts and machinery for wind and solar power are greater than any saved emissions from the facilities. “You use more fossil fuels to do this than you’re getting benefit from it,” says Ozzie Zehner, one of the movie’s producers. “You would have been better off burning the fossil fuels in the first place instead of playing pretend.”
But that statement isn’t supported by data. For example, the film claims that “some solar panels” last only 10 years, but today’s solar panels are built to last 20 to 30 years. Similarly, wind turbines have a life span of about 20 to 25 years, according to the U.S. Energy Information Administration.
A 2017 study in Nature Energy reported that the lifetime carbon footprints of solar, wind and nuclear energy power plants are just a fraction of the lifetime footprints of coal and natural gas plants. The study also projects that, in 2050, the energy involved in constructing and operating a solar or wind power plant will be just 3 to 8 percent of its electricity output.
Solar and wind power are too intermittent to ever fully replace fossil fuels.
The question of storing energy generated by renewables so it’s available when the sun isn’t shining or the wind isn’t blowing has dogged renewables for decades (SN: 1/9/17). But battery storage does exist: Some renewable companies use lithium-ion batteries, for example (SN: 5/7/19). And renewable energy utilities in the United States, Australia, Germany, Japan and elsewhere use battery storage systems, though so far they are primarily for short-term storage, amounting to a few hours.
In the film, Gibbs suggests that battery storage capacity — how much energy the batteries can store — is the main obstacle to updating the traditional energy grid. He shows a pie chart apparently based on data from the Paris-based International Energy Agency, which he says shows that current total battery storage capacity is 51 trillion British thermal units. That’s “less than one-tenth of 1 percent of what’s needed” for a year’s worth of energy usage around the globe.
The problem with that argument is that it’s a false premise: To integrate renewables into the grid, it’s not necessary to have enough capacity to match peak global demand — meaning, all of the world’s global energy needs, all at the same time. Instead, as energy writer Ketan Joshi noted on Twitter, an optimized mix of different renewable technologies (and some storage) can work together to keep the lights on.
Rather than capacity, the real obstacle to utility-scale energy storage is price. A 2019 study in Joule noted that for wind and solar power to completely power the United States, energy storage would need to be highly cost-competitive, with a maximum price tag of just $20 per kilowatt-hour, about 90 percent cheaper than it currently is. The materials in lithium-ion batteries are too expensive to hit that target, but researchers are developing other battery materials, such as sodium sulfur and sodium nickel chloride, that could be much cheaper.
Replacing coal plants with natural gas plants isn’t an improvement.
Across the United States, utilities have been moving away from coal — partly due to costly environmental regulations and partly due to increasing competition from other sources of electricity. As a result, many energy giants, such as Duke Energy, say they are replacing these coal plants with clean energy sources. As Planet of the Humans correctly notes, this very often means a replacement with another type of fossil fuel: natural gas.
By around 2016, natural gas replaced coal as the leading source of electrical power in the United States, according to the EIA. In 2019, natural gas provided about 38 percent of the nation’s electricity compared with coal’s roughly 24 percent.
The movie suggests that companies are greenwashing this shift by calling these natural gas power plants clean. Sure. The movie also suggests that environmental groups such as the Sierra Club, which has led the charge to retire U.S. coal-fired power plants, are equally culpable for not making the distinction between natural gas and renewable energies when talking about clean energy. This is demonstrably untrue.
Bottom line, natural gas isn’t clean, but it is cleaner than coal. Natural gas emits as little as 50 to 60 percent of the carbon dioxide of a coal plant. Coal burning also adds toxic heavy metals such as mercury and arsenic to the atmosphere and to waterways, not to mention the polluted waterways and denuded mountaintops that come with coal mining. For these reasons, eliminating coal has been (and should be) a top priority for environmental activists.
But it’s fair to say that natural gas has some problems (oddly not ones discussed in the movie), and there’s good reason to be cautious. About two-thirds of new U.S. oil and gas wells are using hydraulic fracturing, breaking apart shale and other rocks deep underground to extract the gas (SN: 8/24/12). Fracking has a host of possible hazardous consequences, not least its link to earthquakes (SN: 1/18/18). Moreover, natural gas plants can leak large amounts of the potent greenhouse gas methane to the atmosphere due to faulty infrastructure as well as venting (SN: 4/22/20).
By pointing out problems, Gibbs and Moore have said that they just wanted Planet of the Humans to start a conversation about the renewable energy industry. Indeed, the film poses many questions about the industry and the environmental groups that advocate for it. But the film offers no alternative solutions (it hints that perhaps there are just too many people on the planet for any sustainable solution but stops short of advocating for outright population control).
This “just asking questions” trope is another way that the movie feels out of date. As last year’s climate protests revealed, people don’t need this movie to spur them to outrage or activism (SN: 12/16/19). They’re already there. And they definitely don’t need bad or incomplete information with which to combat the climate crisis.
Source: Heart - www.sciencenews.org
