CHAPTER FIVE
100 Percent Renewables?
“WE DON’T NEED nuclear power” goes the current conventional thinking among environmentalists. “We can build 100 percent renewables.” The demand to generate all the world’s energy needs from renewable sources—hydroelectric power, wind power, and solar power—has become a mantra for much of the climate-action movement.1 Tell your city and state to provide 100 percent renewables. Power your corporation with 100 percent renewables. As a slogan, it’s catchy and simple. And it moves in the right direction. Every time a solar farm replaces a fossil power plant, that’s a victory.
But it doesn’t add up to a complete solution, certainly not in the upcoming decades in which climate solutions must be found.2 Over the past decade, the world has spent $2 trillion on wind and solar power but has seen almost no progress toward decarbonization.3
To start with, new renewables alone do not scale up fast enough for the rapid decarbonization that we need, even if they were not variable and uncertain (which, as we shall see, is a serious issue). We need renewables to make their contribution, but we also need all other tools in the box to achieve rapid decarbonization. We need “nuables”—nuclear power plus renewables—both scaling up as fast as possible. But nuclear power can scale up faster than renewables can. Fundamentally, this is because the energy in nuclear fuel is millions of times more concentrated than wind or solar power.
To assess this question of speed, consider the historical experience of countries’ rollout of nuclear power compared with the rates of rolling out renewables in recent years. In assessing alternatives for decarbonizing the world, a key measure is this: How much carbon-free energy was a country able to add per year, relative to population or GDP, during a peak decade of rollout? By this measure, all the recent increases in renewables fall far short of what was accomplished decades ago in rolling out nuclear power in various countries—with Sweden leading the list. For instance, each year during the peak decade of 2005–2015, German wind and solar power combined added about 120 kWh/year per person. California added about 70. By comparison, Sweden in its peak decade added over 600 kWh/person each year, and France added 450.4
The point we made in Chapter 3 about Germany’s Energiewende policy applies globally: What the world already knows how to do in ten to twenty years using nuclear power would take more than a century using renewables alone. The story of using only renewables seems compelling, but the scale does not work to rapidly decarbonize the world.
Nuclear power, even today with its many challenges, still adds power quickly. Although Finland’s new EPR has faced massive budget overruns and construction delays, it will add clean electricity faster, over that extended time line of delays, than the world record for doing so with wind and solar combined. Upon connection with the grid in 2018, the new Finnish reactor was to generate about as much electricity annually as all the wind turbines Denmark has built since 1990.5
India has committed to an impressive goal of installing 100 GW of solar power by 2022. Yet, even if successful, which is far from certain, this effort would only slow the growth of coal use in India. For one thing, the 100 GW of intermittent solar would produce only the electricity equivalent to about 25 GW of round-the-clock coal (or nuclear power). And that new power would be installed over five years, so it adds about 5 GW a year, modestly more than a single Ringhals plant each year. In terms of production, that new solar power could generate something like 40 terawatt-hours per year. But just the new customers on India’s grid each year require almost that much electricity (see the previous chapter).6 With existing customers wanting a lot more electricity too, even this ambitious Indian solar plan will not reduce coal use. Similarly in other developing countries, the growth of renewables can at best keep up with new demand, not displace existing coal power.
China, despite being the world’s leader in renewable energy, continues to burn mountains of coal. Coal accounted for 72 percent of China’s electricity production in 2015, with wind below 3 percent and solar below 1 percent. Plans through 2040 show little decline in the actual amount of coal used, although its share declines to about 50 percent as total production rises.7
Figure 18. World electricity generation by fuel, 1980–2014, in terawatt-hours. Renewables refers to wind, solar, biomass, and geothermal power. Data source: World Bank.
Worldwide, including both electricity and other forms of energy, all types of renewable power combined other than hydropower today provide only about 3 percent of the total primary energy supply.8
Hydropower
Two-thirds of renewable energy worldwide comes from hydroelectric power. Hydropower is great from a carbon-mitigating point of view, but most of the prime sites have already been dammed. Building a new hydroelectric dam typically involves flooding vast areas of land, displacing populations, and embarking on a large-scale, capital-intensive construction project. Because of a lack of suitable sites, hydro does not scale up quickly in the way we need now. As climate change causes more frequent and severe droughts, hydropower also faces the problem of dry reservoirs, which do not produce electricity.
While large-scale hydroelectric power is a fossil-free energy source, in many ways far superior to fossil alternatives, sometimes the rush to hydro in developing countries may have far-reaching and unintended consequences. A recent Economist essay described the potentially devastating effects of the many hydroelectric dams being developed on the Mekong River in Southeast Asia, one of the most biodiverse ecosystems on the planet and the foundation for 15 percent of global rice production.9 In 2018, one of the more than fifty hydroelectric dams under construction in Laos burst and killed scores of people.10 As more and more dams are developed, fisheries, agriculture, and biodiversity will suffer, the extent of which we have no good way of estimating. This again highlights the benefits of a portfolio approach to clean energy—simultaneously building solar, wind, hydro, and nuclear power to avoid having to rely on environmentally damaging or risky projects.
Wind
Wind power produces electricity at reasonably low cost. However, it needs a lot of area, and the windiest places are generally far from the cities where electricity is consumed. This means large, expensive upgrades to the electric grid, such as Texas recently undertook. Offshore wind could help to solve this problem, since wind farms offshore could be close to coastal cities—and offshore winds are generally steadier than those onshore—but prime locations are somewhat limited. For example, California’s seafloor drops off rather steeply compared with Britain’s. Sweden’s largest offshore wind farm, at Lillgrund near the bridge to Denmark, was built in 2007 in a good location, in shallow water close to shore, but produces electricity at about 11 cents/kWh compared with about 4 cents for methane and is losing money.11 Globally, a recent analysis estimates offshore wind costs at 11 cents/kWh versus 3–6 cents for onshore wind.12 And offshore wind farms generally are supposed to last for twenty-five years, but there is some evidence that shorter life spans than expected may add to the ultimate price.13
Figure 19. Offshore wind is a key part of renewables expansion, but still expensive. Sweden’s Lillgrund wind farm, 2007. Photo: Mariusz Paździora via Wikimedia Common (CC BY-SA 3.0).
Nonetheless, offshore wind costs have dropped significantly in recent years. In 2017 a large offshore wind project in Britain was priced at about 8 cents/kWh, half the price of just a few years earlier.14 Other prices are higher, however. The first offshore wind farm in the United States—Deepwater Wind off Block Island, Rhode Island, completed in December 2016—produces electricity at almost 24 cents/kWh. A newly approved offshore wind farm near Long Island, not yet built, will come in at 16 cents, which is still more than double the utility’s average electricity rate.15
And wind is variable. Not only does it blow more at some times of day than others, but in some years more than others. As noted in Chapter 3, Germany’s wind power produced about 10 percent less electricity in 2016 than in 2015 relative to installed capacity.
Replacing coal power plants with nuclear power plants is straightforward. Both are “baseload” power, available around the clock. By contrast, trying to replace coal with wind or other renewables is complicated by the variable and uncertain nature of renewables’ production, which must be balanced by either hydropower or methane (which can ramp generation up and down quickly). In the extreme case, which sometimes occurs, a rush of wind power onto the grid on a windy day forces steam from a nearby coal plant to be vented (and hence wasted) rather than used to run a turbine and generate electricity. It is simply not feasible for the coal plant to power up and down to match the ups and downs in the wind. New methane plants can do this more feasibly (at some cost), but this problem means that the rollout of renewables often goes hand in hand with a rollout of methane power to balance the load. More often, rather than vent steam from a coal plant, electric grids “curtail” wind or solar power, wasting their potential output rather than letting it on the grid. This has particularly affected China’s massive wind farms, where curtailment has recently caused a reduction of about 20 percent in wind-power generation in the country.16
Solar
Solar power is abundant but starts from barely more than 1 percent of world electricity supply today. Like wind, it has an important role to play but also has limits.
If you sit at your computer in the United States some afternoon and look at the map of real-time energy generation by source in Europe, you may be struck by a startling observation. In Europe it is evening, and—although lights are on, people are moving, and heating or air-conditioning is cranking—the solar generation across the continent is zero.17 Solar power is not just variable like wind but totally unavailable for major parts of every day. Hydropower in some countries can compensate for this daily fluctuation, as it can for ups and downs in wind, but in northern countries solar power drops drastically for months at a time. Solar production is near zero in winter, just when lighting and heating needs peak.
The intermittency of solar power means not only too little at times but too much at other times. The grid cannot accommodate big surges during peak solar production. California gets more than 10 percent of its electricity from utility-scale solar power and another 4 percent from rooftop solar. As with Chinese wind power, California has had to force curtailments on its solar production—15 percent of the time in 2015 growing to 30 percent in early 2017. Because solar is decentralized and hard to control, especially for rooftops, California still regularly ends up with too much production and, to avoid overloading the grid, pays Arizona to take some of it. This is called “negative pricing,” frequently at a substantial price of 2.5 cents/kWh.18 (Germany has a similar negative pricing problem, as mentioned in Chapter 3.)
California renewables are mandated by the state government to grow from 25 percent of total electricity to 50 percent by 2030. A new 2018 regulation requires that every new home in the state have solar power.19 At the same time, California is removing the 10 percent of electricity still generated by baseload 24/7 nuclear power. Hydropower production is becoming unstable as climate changes, because drought one year becomes deluge the next. So the problem of intermittency will get much worse in the coming decade. California’s electricity, already about 50 percent more expensive than the national average, will likely increase further in price.
Solar advocates celebrate the large amounts of solar power being installed these days, but the added capacity does not translate to production in the same way other sources do. Headlines that compare installation of new solar capacity with new coal capacity are not as positive as they sound—first, because solar produces far less power for each GW of capacity and, second, because installing any amount of new coal power is a step in the wrong direction when we need a power source to replace coal quickly.20
Solar costs have dropped steeply in the past few years. If not for intermittency, solar power could compete with fossil fuels in many places. The International Energy Agency (IEA)’s analysis of levelized costs of energy, for generating sources entering service in 2022, lists solar farms at 7.4 cents/kWh and methane at 5.4 cents, before subsidies.21 The solar costs continue to drop.
But solar plus long-term battery storage, to solve intermittency, is still impractical and quite expensive. Recently, news reports heralded an agreement in Tucson, Arizona, to provide solar power plus battery storage for just 4.5 cents/kWh, a price competitive with coal or gas generation. On further inspection, however, the cost was heavily subsidized by the city, and the battery storage was good for only about fifteen minutes of storage, just to smooth out the grid from the shock of crashing production each afternoon when the sun goes down. Fifteen minutes after the sun sets, the system generates electricity from methane or coal.22
The cost of rooftop (or “distributed”) solar is much higher than “utility-scale” solar power in large farms. By one analysis, utility-scale solar in a favorable location such as the Southwest United States, and with no consideration of the costs of intermittency, can cost as little as 5 cents/kWh. Residential rooftop solar in the same analysis costs 19–32 cents,23 although costs continue to drop. Solar cells on rooftops are an iconic image of cool renewables but not really practical as a grid-scale solution to replacing fossil fuels.
The definitive new book on solar power, Varun Sivaram’s Taming the Sun, warns that our current path will not lead to a solar-powered one-third share of world electricity by 2050, needed to reach climate targets.24 As more and more solar is added to the grid, its value falls even though the price of the solar cells keeps declining. This is because solar power produces cheap electricity only at times when there is already a surplus of electricity—more and more of a surplus as solar’s share of the total grows.
Although cheap solar cells resulted from massive subsidies both at the producing end (especially in China) and the consuming end (mostly Western countries), by now economies of scale, and at times oversupply, have made them cheap even without subsidies. Some new installations have guaranteed prices as low as around 3 cents/kWh, lower than any other source.
Figure 20. Europe by night: lights on but solar power off. National Aeronautics and Space Administration composite, 2014. Photo: NASA Goddard.
When solar is just a few percent of the total, the grid absorbs it easily, and the cheap price is a blessing. But as solar grows to 10 or 20 percent of the total, this production dominates the grid when the sun is shining and suddenly leaves a huge gap when night, clouds, or seasons stop the sun shining. We have mentioned that electricity prices go negative when renewables production is high in Germany and California. Adding more solar cells means producing more at these times. Electricity at 3 cents/kWh is no bargain when electricity is being given away free. A cheap ice cream cone in a remote desert would be a bargain, but a thousand more would be worthless unless you had a freezer. You could neither eat them nor save them. Currently, we lack affordable, long-term, grid-scale electricity storage—the equivalent of the ice cream freezer.
Because of problems such as this, solar power in the leading European solar countries—Italy, Greece, Germany, and Spain—topped out at 5–10 percent of total electricity and saw no growth at all from 2014 to 2016.25 California has pushed past 15 percent of the total, but at a cost. On a sunny day, almost half of California’s electricity comes from solar power, and methane is only 10 percent. When the sun goes down, methane and imports from Nevada and Arizona (methane, coal, and nuclear power) fire up to fill that gap, about one-third of total demand. In the morning the same massive shift happens in reverse.26 To accommodate those surges, the grid needs backup fossil-fuel plants and transmission lines at the ready, as well as upgrades to help the grid cope with variability. These costs add up. Turning methane plants on and off is inefficient and wears out equipment. Germany is spending $20 billion on grid upgrades and expensive backup plants, and its neighbors complain that German fluctuations destabilize their own grids.27
The hidden costs of integrating solar onto the grid add about 50 percent to the stated cost of solar power, according to Sivaram.28 This is in addition to subsidies from producing and consuming countries. None of these costs are included when cheap solar power is discussed. In California solar generators get paid for their electricity production whether it’s needed or not.29 As a result, California has the most expensive electricity in the country, rising from 35 percent above the national average to 60 percent above just from 2011 to 2017 as renewables expanded. German consumers pay one-quarter of their high bills to support renewables. In fact, everywhere that renewables have expanded most, electricity prices have risen.30 Solar farms also do have environmental impacts (though certainly far fewer than coal). They eat up large amounts of land because sunshine, although potent in the aggregate, is spread out across Earth. Ramping up solar production would mean paving over many square miles at a time, often consisting of productive farmland or undeveloped nature, with steel and silicon. This loss of cropland and habitat runs counter to other climate-change goals. The neighbors do not always approve of the change, and solar projects can be tied up in court for years. At the back end of the cycle, solar cells last only about twenty-five years, after which they must be recycled, which is a large-scale, dirty, toxic operation often carried out by children in very poor countries with few safeguards. Unlike for nuclear power, the costs of decommissioning solar farms are not usually included in the price.
Batteries
Because wind and sun both come and go, a grid dominated by renewables would depend on cheap energy storage, such as new breakthrough battery technologies. However, these do not yet exist and may not for years. Today’s best consumer batteries, such as Tesla’s Powerwall unit, are too expensive for grid-scale storage. (The very largest of such batteries, such as Tesla’s famous battery in Australia, can provide some short-term stabilization to the grid at a price competitive with other methods such as methane peaker plants. Using such batteries to hold renewable power long term is still not affordable.) The potentially cheapest large-scale batteries—flow batteries using large tanks of liquid—are more promising but still too expensive. So far, lithium-ion batteries are the most economical and proven. Large-scale battery installations are dropping in cost as the industry matures.31 Used on a grid scale, battery storage adds about 30 cents/kWh to the cost of electricity, whereas for “behind the meter” commercial and residential use the cost is 85 cents to $1.27/kWh.32 (Recall that the average US electricity price is now 10 cents/kWh.)
For the very cheapest solar installation available—a thin-film utility-scale solar farm in the Southwest United States—a recent comprehensive analysis found that the cost of adding just ten hours of storage would nearly double the cost of electricity.33 This makes solar plus storage more expensive than fossil fuel and impractical for developing countries, much less for locations where the sun fails to shine for more than ten hours at a time.
In a world that currently uses about 68 TWh/day of electricity,34 the investment in batteries to store just one day’s worth of production would exceed $20 trillion, which is about a quarter of all economic activity in the world in a year. That is just the storage cost, added to the cost of producing electricity. Nor is it clear that one day of storage would suffice; as we noted in Chapter 3 regarding Germany’s Energiewende ambitions, there are periods of a week when solar and wind combined drop below 10 percent of capacity for all of Europe.
Production of batteries to power the world on renewables would be mind-boggling in terms of not only cost but also production capacity and supply of raw materials. The world’s current annual production of lithium-ion batteries, like those in electric vehicles and Tesla Powerwalls, would power the world’s electricity needs for about forty-five seconds. Tesla’s “gigafactory” in Nevada will double this rate of world total lithium battery production when it reaches full production.35 If you built a new gigafactory every year (the first one took five years), it would take sixty years to cumulatively produce enough batteries to hold just one day’s storage of the world’s electricity. However, since batteries have a limited life of charging cycles, even the most high-end batteries typically do not last longer than fifteen years when operated on a daily load cycle, so more decades would be needed to replace the dead batteries from the early decades. And, of course, the “one day’s storage” at today’s electricity consumption rate would not meet the need in sixty years when world electricity consumption will probably have doubled. Solving climate change requires much faster decarbonization than that.
Bill Gates, who has invested $1 billion in renewables, states, “There’s no battery technology that’s even close to allowing us to take all of our energy from renewables and be able to use battery storage in order to deal not only with the 24-hour cycle but also with long periods of time where it’s cloudy and you don’t have sun or you don’t have wind.”36 As the latest report from Lazard, the authoritative source on energy costs, puts it, “Although alternative energy is increasingly cost-competitive and storage technology holds great promise, alternative energy systems alone will not be capable of meeting the base-load generation needs of a developed economy for the foreseeable future.”37
All these problems might be overcome with enough time. Perhaps later in the century, if there were a huge breakthrough in the cost of batteries, we could find the US
northeastern seaboard powered by massive offshore wind farms. But it would be very irresponsible to depend, for humanity’s future, on solutions that we hope will appear decades from now and that depend on technological breakthroughs that have not yet occurred—when we have methods available that are already proven to work. Cheap batteries or fusion power might save us. The asteroid might miss us altogether. But these are not the chances a responsible person takes. Wind and solar power have a growing and vital role to play in replacing fossil fuels, but starting from just 5 percent of world electricity supply, that role alone does not scale up fast enough to make the math work to say “we don’t need nuclear power.”
Making Solutions Add Up
The “Solutions Project” and Stanford professor Mark Jacobson caused a huge stir recently with their claim that the United States38 and the world39 could be both cheaply and reliably powered by 100 percent renewables by midcentury. A subsequent article in the same journal by a distinguished group of experts, including other Stanford professors, rebuts these claims.40 In the US case, the 100 percent–renewable scenario depended heavily on huge increases in hydropower that do not appear to be feasible. Because hydropower can balance out the variability of wind and solar power, such as by opening up more water flow at night when solar cells are offline, this assumption of vastly increased hydropower propped up the whole scenario. It doesn’t add up. Jacobson’s response to his critics was to sue them and the National Academy of Sciences in court for $10 million—an extremely irregular way to address an academic dispute in a scientific journal. (He later dropped the lawsuit, leaving legal costs for the defendants to pay and a chilling effect on the research community.)
What does add up is an important and growing role for hydro, wind, and solar power in the coming decades. The faster these energy sources are deployed, the easier will be the job of rapidly decarbonizing. Partnered with nuclear power in a “nuables” solution, they are a key part of fixing climate change.
The mistake is thinking that those steps in the right direction will add up and solve climate change alone. They won’t. Bolstering renewables to reach 50 percent of the world’s growing electricity production would be a great step in the coming decades. But “100 percent renewables” is a slogan that distracts from the work at hand, which is the decarbonization of the world.
An example of this distraction factor is the Climate Simulator published on the New York Times website in 2017.41 Based on the MIT model described in Chapter 1, it brilliantly steps the reader through the math to show the need for immediate, massive decreases in CO2 emissions if the world is to stay within limits. However, the graphic then claims (without any evidence) that, good news, such cuts “may be possible” with wind, solar power, and energy efficiency. These solutions, however, cannot achieve precisely what the model itself shows to be necessary—a rapid decrease in emissions. A more useful simulator would go on to let the reader try out various technologies, to see that without a major expansion of nuclear power, the targets simply cannot be met.
Beyond just distracting from solutions that add up, the 100 percent–renewables idea has been used repeatedly as a rationale to shut down existing zero-carbon nuclear power plants with the idea that they can be “replaced” with renewables. But as we build out renewables, we absolutely must use them to replace fossil fuels, not carbon-free nuclear power. After the last fossil power plant closes, and we have only nuclear power and renewables, then we could talk about whether to replace the nuclear power capacity with renewables if it proved practical and beneficial. This is what some Swedes hope to do in a few decades, although the published science shows that it would actually be better environmentally and economically to keep Sweden’s nuclear power plants running.42
Figure 21. “Replacing nuclear with renewables” does not decrease carbon emissions. Graphic: Vaclav Volrab / Shutterstock.
So far, we have discussed wind and solar power as additions to the electrical grid, but one version of the all-renewables argument holds that communities can use renewables to break free of the grid altogether. Chapter 4 discussed the failure of this approach in an experiment in India. It has also been tried recently for a small village in southern Sweden. A German utility powered the village with a local microgrid supplied with locally produced solar and wind electricity, without reliance on the national electricity grid. But in practice, the system needed to draw more than 80 percent of its electricity supply from the national grid.43 The utility bluntly noted, “If you look at this when it’s very cold outside, the wind is rarely blowing and it’s also dark, so the solar cells are not producing. That’s the way it is, and everyone knows that.”44 For each unit of electricity the village installation does manage to produce from its own sources—which include solar cells, wind turbines, batteries, and a biodiesel backup generator—the carbon emissions are higher than for electricity imported from the national grid.45
The 2017 book and website Drawdown lists eighty “solutions” that move in the right direction, casting them as “the most comprehensive plan ever proposed to reverse global warming.” The solutions range from obvious ones such as rooftop solar panels to indirect ones such as expanding girls’ education, as well as future technologies that do not yet exist, such as artificial leaves and hydrogen-boron fusion. Adding up the solutions in a “plausible scenario,” which they describe as “reasonable yet optimistic,” the authors find the solutions actually would not achieve the needed drawdown.46
One of the Drawdown solutions is nuclear power (number twenty on the list of eighty), which the authors assume will grow by 2030 and still provide 12 percent of the world’s electricity by 2050. Given the need to “do everything we can,” as the authors put it, one might expect strong support for expanding nuclear power’s role. Instead, the editor has added a special “Editor’s Note” unique to the nuclear power solution, stating that while almost all the other solutions are “no-regrets” actions with many beneficial effects, nuclear power is a “regrets solution” because of the negative effects. He lists fourteen names of places where nuclear power problems have occurred, such as “Browns Ferry”—evidently a reference to a 1975 fire that did not cause a meltdown, human casualties, or release of radiation.47 What he does not claim is that we can solve climate change without this “regrets solution.”
The Drawdown approach is far more comprehensive and sophisticated than a simple “all we need is 100 percent renewables” line. At the same time, it suffers from a similar problem, which is to focus on steps that move in the right direction without examining what feasible measures can actually solve the problem of climate change.
The promotion of 100 percent renewables also contributes to the skewing of public opinion away from nuclear power. After a well-funded, decades-long global fear campaign against nuclear power, people are anxious about it, and renewables seem to offer a comfortable alternative to combat climate change without confronting those anxieties. In China and India, a 2015 public opinion poll shows that about half the public supports the development of more renewables, about a quarter supports the expansion of fossil fuels, and less than 10 percent supports the expansion of nuclear power.48 In the West, too, publics support clean, cool options but do not evaluate whether they actually solve the problem.
When a company, university, or town declares that it has achieved “100 percent renewable” electricity, that statement is not true. It should say net power of 100 percent, with a lot of extra clean energy sold to the grid part of the time (often when it’s least needed) and a lot of dirty energy of equivalent amount bought from the grid at other times. As we have seen, this is a far cry from not needing dirty energy. True reliance on 100 percent renewables would mean disconnecting from the grid without relying on backup fossil-fueled generators. Almost nobody has done this because it is not practical or affordable. And currently it is no more practical for a country than for a company.
Renewables are an important part of the solution to climate change. Costs for wind power and, especially, solar power are dropping dramatically in recent years.49 In places where they can be feasibly and economically added to the grid, they can help displace fossil fuels. (This is far more practical when they are a small part of the total on the grid. For example, it makes more sense to focus on adding renewables in China, where three-quarters of the electricity comes from coal and only about 5 percent from wind and solar, than in Germany and California, where renewables already provide about a third of electricity.) So, by all means, let’s build renewables, but let’s keep our attention focused on what needs to be done in the next ten to twenty years to rapidly decarbonize the world and not fall into the delusion that 100 percent renewables is the solution.