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A practical guide to using the climate law to get cheaper solar panels, heat pumps, and more.
The new rules are complicated. Here’s how to make sense of them if you’re shopping for an electric vehicle.
The long-delayed risk disclosure regulation is almost here.
Here’s what you need to know about the nuclear power comeback — including what’s going on, what’s new this time, and is it safe?
For a while there, nuclear energy looked like it was on its way out. After taking off post-World War II, it lost momentum toward the dawn of the 21st century, when sagging public support and mounting costs led to dozens of cancellations in the U.S. and drove the rate of new proposals off a cliff. Only a few reactors have been built in the U.S. this century; the most recent, Georgia Power’s Plant Vogtle units 3 and 4, were years behind schedule and billions of dollars over budget. Vogtle-3 came online last summer, with Vogtle-4 — which was delayed even further by an equipment malfunction — expected to follow early this year.
It’s funny how time works, though. With demand for reliable zero-carbon energy rising, a new wave of nuclear developers is trying to recapture some of the industry’s long-lost momentum. They’re entering the race to net-zero with big ambitions — and much smaller reactor designs. Whether you’re wondering about the state of the U.S. nuclear power sector, what’s new about new nuclear, where the nuclear waste is going, and of course, whether it’s safe, read on.
Let’s start with the basics.
Nuclear reactors generate electricity using a process called fission. Inside the reactor’s core, a controlled chain reaction splits unstable uranium-235 into smaller elements; that process releases heat — a lot of heat.
The reactors in today’s U.S. nuclear fleet fall into two categories: boiling water reactors and pressurized water reactors. Each circulates water through the reactor core to manage the temperature and prevent meltdowns, and both use the heat produced by fission to create steam that powers turbines and thereby generates electricity. The main difference is in the details: Boiling water reactors use their coolant water to produce electricity directly, by capturing the steam, whereas pressurized water reactors keep their coolant water in a separate system that’s under enough pressure to prevent the water from turning to steam.
Some experimental reactors and newer commercial designs use different cooling systems, but we’ll get into those later. Lastly, while nuclear energy is not considered renewable, in the sense that it relies on a finite resource (enriched uranium) for fuel, it is a zero-emission energy source.
The sector emerged in the late 1950s and expanded rapidly over the next several decades. At its peak, the country’s nuclear fleet included 112 reactors — a number that has declined to about 90 today. Most of the surviving plants were built between 1970 and 1990.
The shrinkage has partly to do with the nuclear disarmament movement, which arose during the Cold War and grew to encompass nuclear power development, as well. (As it happens, much of the present day environmental movement has its roots in anti-nuclear activism.) Then there was the partial nuclear meltdown at Three Mile Island in 1979, which intensified existing public opposition to nuclear energy projects. That growing pushback, combined with reduced growth in electricity demand and the significant up-front investments nuclear plants required, caused some projects to be scrapped and fewer to be proposed. The Chernobyl nuclear disaster in 1986 seemed to confirm everyone’s worst fears.
Interest began to reemerge in the U.S. in the early 2000s as the budding public awareness of climate change cast doubt on the future viability of fossil fuels, but the 2011 Fukushima nuclear accident quashed many of those plans. The last U.S. nuclear plant to start up before Vogtle-3 entered construction in 1973 but was suspended for two decades before its completion in 2016.
As of 2022, 18.2% of U.S. electricity came from the country’s remaining nuclear reactors, according to federal data. That’s less than we’ve seen in decades.
The share of nuclear power on the grid has been slowly dwindling as aging reactors are shut down and other resources — mainly natural gas and renewables — have taken on a greater proportion of the country’s electricity-generating burden. The share of electricity from renewables surpassed energy from nuclear for the first time in 2021; in 2022, renewables contributed 21.3% of U.S. electricity.
Like coal and gas plants (and renewables when paired with sufficient storage), nuclear provides baseload power — meaning it sends electricity onto the grid at a consistent, predictable rate — as opposed to sources like wind and solar on their own, which provide intermittent supply. Electric utilities depend heavily on nuclear plants and other baseload resources to match supply with continuously fluctuating demand, accommodating the variability of wind and solar without sending too much or too little power onto the grid, which would cause power surges or blackouts.
Generating electricity using nuclear fission remains a divisive issue that cuts across partisan lines. In the inaugural Heatmap Climate Poll, nuclear came in a distant last among clean energy sources people feel comfortable having in their communities.
Some major environmental groups like the Sierra Club and Greenpeace maintain that the risk of serious disasters at nuclear power plants poses an unacceptable risk to communities and ecosystems. Others, including the Nature Conservancy, view it as a reliable low-carbon energy resource that’s — crucially — available to us today, while promising but immature options such as long-duration energy storage are still catching up.
Historically, nuclear has caused far fewer fatalities than fossil fuels, which generate all kinds of toxic, potentially deadly pollution — and that’s without factoring in their contribution to climate change and its associated disasters.
The companies now hoping to pioneer a new generation of nuclear reactors in the U.S. say their designs incorporate the lessons learned from the accidents in Chernobyl and Fukushima, putting even more safeguards in place than the fleet of reactors operating across the country today. (There’s still a debate over whether the proposed reactors will actually be safer, though.)
Spent uranium fuel is radioactive, and will remain radioactive for a very long time. As a result, there’s still a lot of disagreement about where that waste should go.
The federal government tried in the early 2000s to create a national repository in Nevada’s Yucca Mountain, but the project was stopped by intense local and regional opposition. The Western Shoshone, a tribe whose members have long faced exposure to radioactive fallout from nearby nuclear tests, sued the federal government in 2005. Harry Reid, a former U.S. Senator from Nevada who served as Majority Leader from 2007 to 2015, also fought against the repository.
In the absence of a central repository, the waste produced by nuclear plants is usually stored in deep water pools, which keep the spent fuel cool, or in steel casks onsite to keep the radiation from escaping into the surrounding environment.
If a repository eventually opens, some existing waste will likely be moved out of temporary storage and relocated there.
In short, the concrete behemoths that have long been the norm in the U.S. are really, really expensive to build. They also — like the two new Vogtle reactors — have a tendency to go way over their deadlines and budgets. That makes the electricity nuclear plants generate particularly expensive.
The vast majority of U.S. coal plants were built during the same few decades as most of the country’s nuclear reactors. But when utilities started to face more pressure to reduce their carbon emissions, toppling coal’s reign over the power sector, utilities wound up preferring to build cheaper — and, at least at the time, less controversial — natural gas power plants over nuclear power plants.
But public opinion is beginning to shift. About 57% of American adults favor building new nuclear power, a Pew Research Center survey found last year, compared with 43% in 2016. Though support is higher among Republicans than Democrats, it’s on the rise within both parties.
Today’s electric grid is a far cry from the 20th-century grid that traditional nuclear reactors were built for, and the new reactor models that are making the most headway reflect those changes. In general, these designs are smaller, cheaper (at least on paper), and more flexible than those already in operation.
Unlike traditional reactors, which generally require a lot of custom fabrication to be completed at the project site, small modular reactors — such as the ones being developed by NuScale Power — have components that are meant to be made in a factory, assembled quickly wherever they’ll operate, and combined with other modules as needed to increase power output. Fast reactors (so-named for their highly energized neutrons), like Bill-Gates-fronted TerraPower’s Natrium design, circulate coolants other than water through the core. (Natrium uses liquid sodium.)
Advocates of next-generation nuclear power are optimistic that the first such reactors will come online before the end of the decade. Several of the leading proposals have run into financial and logistical troubles over the last couple of years, however. In November, NuScale canceled its flagship project at the Idaho National Laboratory. It had been on track to be the first commercial small modular reactor built in the U.S. but was thwarted by rising costs, which caused too many expected buyers of its electricity to pull their support.
Nuclear’s image is recovering globally, too. Some of the companies working on demonstration reactors in the U.S. have been outspoken about wanting to see their designs supplant fossil fuels and provide abundant energy all over the world. Meanwhile, many countries are devoting plenty of their own resources to nuclear power.
Japan, which shuttered its sizable nuclear fleet in the aftermath of the Fukushima accident, is slowly bringing some of its nuclear capacity back online. In December, Japanese regulators lifted an operational ban on the Kashiwazaki-Kariwa Nuclear Power Plant, the largest nuclear plant in the world.
Nuclear power is also enjoying renewed popularity in parts of Europe, including France and the U.K. In France, where the long-dominant technology has faltered in recent years, a half-dozen new nuclear power plants are in the works, and even more small modular reactors could follow. The U.K. is also planning a new wave of nuclear development.
Elsewhere, including in Germany, nuclear hasn’t found the same traction. After delaying the closure of its last three nuclear reactors amid natural gas shortages caused by the war in Ukraine, Germany closed the reactors last spring, eliciting a mixed reaction from environmental groups.
Meanwhile, China has close to 23 gigawatts of nuclear capacity under construction — the “largest nuclear expansion in history,” Jacopo Buongiorno, a professor of nuclear science and engineering at MIT, told CNBC last year.
It’s still early days for most of the world’s next-generation nuclear reactors. With even the most promising designs largely unproven, there’s plenty of uncertainty about where today’s projects will ultimately lead. That makes it tricky to predict what role nuclear power will play in the energy transition over the coming decades.
There’s plenty of interest in building more capacity, however. In December, at COP28, the U.S. and 24 other countries — including Japan, Korea, France and the UK — signed on to a goal of tripling global nuclear energy capacity by 2050 in order to stay on track to reach net-zero emissions by then. Nuclear plants could also be an important source of carbon-free energy for producing green hydrogen, a nascent industry that got a major boost from tax credits under the Inflation Reduction Act.
But the U.S. Energy Information Administration’s most recent capacity forecast projects that the total amount of electricity from the country’s nuclear plants will decline in the coming decades — representing just 13% of net power generation by 2050.
All your questions about our weirdest season, answered.
If you’ve had the uneasy sense that winter weather isn’t what it used to be, you’re not alone — and you’re probably right. The everyday effects of climate change on the year’s coldest months are quickly becoming too blatant to dismiss.
As annual heat records continue to topple year after year — 2023, now officially the hottest year on record, came terrifyingly close to averaging 1.5 degrees Celsius above preindustrial temperatures — winter weather is responding. In some places, it’s turning snowy days into rainy ones. In others, it’s turning cold days bitterly so.
So — what, exactly, is going on? Let’s start with the basics.
The main thing is that climate change is pushing winter temperatures higher. In fact, the average winter temperature is rising faster than that of any other season. Average temperatures in the lower 48 U.S. states from December through February rose by almost 3 degrees Fahrenheit between 1896 and 2021, compared to 2 degrees in spring and 1.5 degrees in summer and fall, federal data show.
The number of days below freezing each year is also on the decline across the country and across the planet. A decade ago, the U.S. was already seeing two weeks less snow cover, on average, than it did in 1972, according to federal data. And parts of the country, including cities in the Northeast and Northwest, are on track to lose over a month of freezing days by midcentury.
But in many places, daily highs and lows aren’t shifting at the same rate. Winter nights, for instance, are warming even faster than winter days — the total number of freezing nights has been dropping in the U.S. since the 1970s. Colder places are also warming more quickly, with the northern U.S. and especially the Northeast experiencing the most significant rise in average winter temperatures.
That dreary, muddy weather that most of the U.S. saw this past Christmas does, admittedly, happen sometimes for natural reasons. Same with the incessant rain that fell (and then turned to ice) across the Midwest and Northeast in mid-January. With every fraction of a degree the planet warms, however, events like these become more likely — or, at least, that’s what hundreds of the world’s leading climate scientists concluded in the United Nations’ latest synthesis report on the state of the global climate.
Bingo.
Some evidence suggests that climate change is actually making cold shocks more likely by destabilizing the polar jet stream, which keeps the frigid air in the far northern hemisphere from moving too far southward (and keeps warm air in the tropics from moving too far northward). As a result, the polar vortex that’s normally confined to the Arctic is liable to stretch south and blast bitterly cold air into the contiguous U.S. That’s what happened in mid-January, when temperatures in Montana and the Dakotas dropped as low as -30 degrees Fahrenheit and the wind chill bottomed out at -60 degrees. Cold air from the same weather system blew all the way to Texas.
That said, this evidence is not rock solid. Whether or not it bears out in the long term, it’s important to remember that a warmer world doesn’t mean it will never be cold.
Recent experience notwithstanding, cold snaps — short periods of abnormally cold weather — are going away, too. Their average duration dropped by six days between 1970 and 2021, a Climate Central analysis found.
One of the most predictable consequences of climate change is that, as year-round temperatures soar, an increasing share of annual precipitation will fall as rain rather than snow. That’s just what you get when it’s too warm for water vapor to freeze.
One of the less obvious consequences, it turns out, is that a warmer atmosphere holds more moisture, enabling it to dump more precipitation — whether that comes as rain, snow, or wintry mix — during a single storm. As a result, even though climate change is making certain places drier, the biggest winter snowstorms are becoming, well, bigger.
This apparent contradiction had a major impact on the parched West in 2023. Drought is expected to become the norm there as the planet warms, fueling epic wildfires and straining already limited water supplies.
But a string of record snowstorms across the West last winter replenished the region’s dwindling snowpack, feeding mountain streams and helping keep drought conditions at bay (and creating a really good year for ski towns). In California, meanwhile, a barrage of atmospheric rivers drenched lower elevations and broke snowfall records in parts of the Sierra Nevada mountains.
California and its neighbors got off to another rainy (and snowy) start in 2024 — though the recent reprieve from years of severe drought isn’t expected to last.
The best answer we can give you today is to say that yes, snow will most likely still exist. But rising generations probably won’t be able to count on snow falling — and sticking — with the regularity it did when you were their age.
Climate scientists don’t have a perfect picture of how quickly the winters we grew up with will give way to a string of months that are rainy, slushy, and unpredictable, but that’s the direction the evidence is pointing. As global temperatures continue to rise, the trends we’ve seen in winter weather over the past couple of decades aren’t expected to reverse course anytime soon.
Many of the ways climate change affects winter are hard to miss. Snow falls later and less often, and when it does come, it doesn’t last as long. That comes with a few perks for the average American — such as fewer frigid winter days — and huge downsides for the communities, ecosystems, and industries that depend on winter being snowy and cold.
The ramifications of warming winters across the U.S. also extend far beyond the end of the season. Accelerated snowmelt causes plants to green and bloom earlier, which can have cascading effects on soil moisture and drought, as well as on the wildlife that depend on these plants for food and habitat. If snowpack fails to accumulate or melts too early, streams will run dry during the hottest months of the year, when animals, plants, and people need them most.
Traditional strains of some fruit crops — like blueberries, cherries and peaches, for example — don’t grow properly in the spring and summer if the preceding winter was too warm. The increasing volatility of winter weather is also affecting the success rate of wintertime crops, especially in the South. By some estimates, the agriculture sector’s biggest companies could lose tens of billions of dollars in value by 2030 because of climate change.
And pests like ticks and mosquitoes are not only expanding northward, they’re also surviving the winter more easily in their historical range, causing their populations to grow and rates of disease transmission to climb.
Unfortunately, that’s one question we can’t answer — not for every instance of unseasonably warm temperatures everywhere in the world. What we do know for sure is that warmer average temperatures make unseasonable and extreme weather more likely. So in that sense, yes, odds are very good that climate change is playing a role in that thermometer reading.
But also, events rarely have just one cause. Climate change could be exacerbating a natural weather phenomenon, or you might just have gotten a brief winter reprieve. Whether one sultry February day is “because of climate change” isn’t really the point. The point is that, unless and until we stop emitting greenhouse gases into the atmosphere and start pulling them out, the weather will just keep getting weirder. There is no new normal.
