Why Wind and Solar Aren’t Enough - Canadian Nuclear Association

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Why Wind and Solar Aren’t Enough

August 9, 2019

When most of us think about renewable energy, we usually mean solar panels and wind farms. Although hydro or geothermal power make for great carbon-free renewable power where they exist, for most of the country wind and solar power are the only real options for renewable energy at scale. And that’s not so bad. Wind and sunshine are free and abundant, and the equipment needed to capture their energy is becoming astonishingly cheap. What could be better?

The problem is intermittency. Solar panels don’t produce at night or on cloudy days. Wind generators stop producing when the wind quits. Needless to say, a city, state, or country’s electrical system must deliver reliable 24/7 power without interruption. That means that an economy dependent on wind or solar must have some other form of generation or storage that can step in and seamlessly fill the power gap when the renewables stop producing.

Today, that gap is being filled by power from the grid. And most grid power is generated bythe only 24/7 sources available—usually, coal or natural gas. And whereas we’d like to believe that building enough wind and solar farms will allow us to close dirty fossil-fueled plants, it’s not so. Those plants have to be kept online to power the grid at night, or whenever clouds cover the sun, or the wind quits. So as long as we have only fossil-fueled plants to fill the gap, carbon emissions will continue to be a problem.

Two real-life examples underscore the point. Germany has spent some $400 billion on its renewable program, yet carbon emissions have remained stubbornly high. Here at home, California made a heavy investment in renewables to replace coal and nuclear, yet the state’s power-sector emissions have actually increased!

So while we’ve done a great job on the technology for capturing energy from the wind and sun, we haven’t done nearly as well addressing the power-gap—the need to backup intermittent renewables with carbon-free energy. As Germany and California show, if solar and wind are to make a serious contribution to the climate problem, we must urgently shift our attention, funding, and efforts to the  development and rapid deployment of carbon-free backup solutions that will supply power at scale 24/7. And those backup solutions must be able to keep on delivering that power, sometimes for weeks at a time.

Batteries would be an ideal solution—if they could deliver full-scale, base-line power for a long enough time.

To understand how big such batteries would need to be, let’s first take a look at the backup needed for solar panels. As every sunbather knows, even on the best days there are only about four hours in the middle of the day when sunshine is strong. Before and after midday, the sun is progressively weaker. Then there is the problem of nights and cloudy days. So perhaps unsurprisingly, even our best solar farms produce significant power only about 25 percent of the time. The rest of the time they produce little or no power. That means a city or economy dependent only on solar farms will need to utilize its backup power source about 75 percent of the time!

Wind is a bit better. Windy Denmark has built so many offshore wind farms that on many days in 2018, the wind supplied more than 100 percent of Denmark’s power. Yet for the full year, wind supplied less than 50 percent. The rest of the time, it filled the gap by buying power from other countries. So an economy dependent on wind farms, even in the windiest locations, will almost surely need to use backup power more than half the time.

The question, then, is whether it is realistic to expect that batteries could ever be large enough to be the backup source that fills the power gap. I am quite certain the answer is an emphatic “no,” not in our lifetime and certainly not in time to prevent massively more carbon emissions.

To appreciate why, consider a specific case for just part of one state. A while ago, well-intentioned activists pushed to close Arizona’s Palo Verde nuclear plant and replace it with solar panels. The plant supplies a third of Arizona’s power and generates about 4 gigawatts (4GW) of 24/7 power. Had the activists been successful and actually replaced Palo Verde with solar panels and batteries, how much battery storage would have been required? Since even Arizona can have a full week of cloudy days, those batteries would have to hold enough electrons to supply power for a week—some 670 GW hours of battery capacity (4GWx24x7). Anything less would leave Arizona in the dark.

How big is 670 GW hours? As a point of comparison, the total battery storage expected to be in place in the United States at the end of 2019—utilities and homes—will be about 3 GW.  In other words, just filling the night and cloudy-day power-gap left by closing the Palo Verde plant would require over 200 times more storage than all the batteries in the United States! What about the largest battery in the world, that giant $66 million Tesla 129 MW battery in Australia? It would take over five thousand of them! But even if all that battery power were somehow possible, it would replace only one power plant that supplies only a third of one state. So although great strides are being made in battery technology and costs, even a technological miracle would not be enough to give us the gigantic amount of battery storage necessary to fill the power-gap at scale.

What, then, are the other realistic possibilities for carbon-free backup? One possibility is to continue to use gas or coal plants and capture and dispose of the plant’s carbon. Given that the world is building two new coal plants each week, carbon capture (CC) is an option that mustbe pursued with much more effort than it is now. Unfortunately, all the present and prospective CC technologies are very energy intensive and expensive. So any serious help from CC is likely decades away. Similarly, all the other methods of supplying backup, such as various forms of hydrogen, are also very energy intensive and expensive. In fact, every known potential solution to the backup problem requires tremendous additional energy—except one. And that one is nuclear energy.

But wait. Rather than nuclear, what about using natural gas as the backup fuel?  Solar and wind backed up with natural gas can be an improvement over 100 percent coal. And very importantly, replacing coal with gas can help the people and communities whose livelihood depends on fossil fuels. As we change our economy to mitigate climate change, we must also mitigate its effect on relevant communities. Using gas as a “bridge” until we can deploy carbon-free solutions will give us time to do that.

But burning natural gas still emits way too much carbon. And even worse, in addition to its CO2 emissions, natural gas is methane, and methane is 100 times worse for climate change than CO2. It’s almost impossible to avoid leakage andscientists say that if just 2 percent of the gas leaks, the climate effect of using gas is worse than if we just kept burning coal. So even under the best conditions, gas won’t get us anywhere near the greenhouse gas reductions we need. Therefore, gas can’t be a permanent solution—or any solution for long.

Which brings us back to nuclear. Even if we don’t love it, nuclear is the only carbon-free generating source that can provide backup power at the scale required. It is also the only carbon-free source we know of that can supply—at scale—the additional energy and heat needed for other carbon-mitigating technologies.

However, the mere mention of nuclear brings up immediate objections, usually centered on safety, cost, and waste. Let’s very briefly look at each in turn.

Safety. The three notable accidents, Three Mile Island, Chernobyl, and Fukushima, were rare exceptions to the safety record of more than a thousand reactors (on ships and land) that have been operating safely for as long as 60 years. No other power or chemical plants come even close to that safety record. Of the three accidents, only one—Chernobyl—resulted in any radiation-caused death or injury. And stories about sterilized land? Again, only around Chernobyl. The Chernobyl accident happened because the reactor was a freak. It was terribly designed, lacked a containment structure and essential safety features, and was incompetently built and operated by the Soviet Union. It was nothing like a modern Generation II or Gen III water-cooled reactor.

Cost. In recent years, plants built in the West have been astronomically expensive. It was not always so. Almost all of the 98 or so nuclear plants operating in the United States today were built before the mid-1970s when utilities chose them for economic reasons—they cost less than equivalent coal or oil plants. But after Three Mile Island, anti-nuclear forces successfully lobbied for massive up-regulation which effectively stopped nuclear by making costs in the United States and the Western world prohibitive. By contrast, the Koreans today build safe, American-designed Gen III nuclear plants for half the cost of a new coal plant—and in less than five years. With more build experience, expertise, and some common sense, America could build safe reactors with build-times and costs just a fraction of what they have recently been.

Waste. Fears of waste have been hugely exaggerated by the media and anti-nuclear lobby.

First of all, there isn’t much of it. All the waste from 60 years of America’s nuclear plant operations would take up less space than one typical Walmart store. Compare that to the much greater space required to store the toxic waste from a single large coal plant. The nuclear waste problem compared to other industrial waste problems is small. And we have all the technology needed to easily, safely, cheaply, and permanently dispose of all our commercial nuclear waste.

In fact, if we updated our regulations, and put some thoughtful planning behind it, we could build enough of the new Gen III reactors to supply all the needed backup with carbon-free energy. And those reactors could all be in place and operating well before 2050. It’s not speculation. France and Sweden converted almost all their fossil plants to nuclear in less than 15 years. We could do the same and have a carbon-free power sector before mid-century.

So far, we’ve been talking about what we could do with existing water-cooled reactors. They’re good—but as good as Gen III is, Gen IV nuclear promises to be even better. Gen IV technologies are not water cooled. Most produce much less waste and some even use existing waste as fuel. They are of little value to terrorists or weapons-makers. Best of all, they are walk-away safe—the reaction stops automatically if the reactor gets too hot, and no operator or mechanical intervention is necessary. For people who can’t accept water-cooled reactors, Gen IV can be the answer.

Happily, there are more than 50 entrepreneurial ventures in the United States working on Gen IV reactors. Some are getting close. Oklo is ready to go with a reactor that doesn’t require maintenance or refueling for 20 years or more and is small enough to fit in a freight container. Thorcon has a design for floating reactors built in shipyards that could be ready to go in less than seven years. But Gen IV companies can’t get permission to build them. Our regulatory system is the problem. It is set up for water-cooled reactors and not equipped to handle anything else. Before any Gen IV reactors can be built and brought to market, major changes must be made to the regulatory system.

Finally, to solve the climate problem, the United States cannot do it alone. The rest of the world must also stop emitting carbon. This is particularly true for the developing world as it searches for ways to satisfy its immense appetite for economy-scale power. That appetite will be satisfied with coal unless there is something better and cheaper available. Gen IV could be that something. And in addition to saving the planet, Gen IV represents an incredible economic opportunity.

The point is that if we’re going to get serious about mitigating climate change, we’ve got to get off the dime now! The next few decades will determine just how hot this planet will get. Just building solar and wind farms won’t solve the problem, since they must have full-scale, reliable, carbon-free backup. And we cannot wait for some future hope. We can and we must act now with what we have today. Otherwise net zero emissions will have been just a dream that our grandchildren will hate us for not achieving. Especially when it was within reach.

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