Once upon a time, if you were an American who didn’t like nuclear energy, you had to stage sit-ins and marches and chain yourself to various inanimate objects in hopes of closing the nation’s nuclear power plants. Today … all you have to do is sit back and wait.

There are 99 nuclear reactors producing electricity in the United States today. Collectively, they’re responsible for producing about 20 percent of the electricity we use each year. But those reactors are, to put it delicately, of a certain age. The average age of a nuclear power plant in this country is 38 years old (compared with 24 years old for a natural gas power plant). Some are shutting down. New ones aren’t being built. And the ones still operational can’t compete with other sources of power on price. Just last week, several outlets reported on a leaked memo detailing a proposed Trump administration plan directing electric utilities to buy more from nuclear generators and coal plants in an effort to prop up the two struggling industries. The proposal is likely to butt up against political and legal opposition, even from within the electrical industry, in part because it would involve invoking Cold War-era emergency powers that constitute an unprecedented level of federal intervention in electricity markets. But without some type of public assistance, the nuclear industry is likely headed toward oblivion.

“Is [nuclear power] dying under its own weight? Yeah, probably,” said Granger Morgan, professor of engineering and public policy at Carnegie Mellon University.

Morgan isn’t pleased by this situation. He sees nuclear energy as a crucial part of our ability to reduce the risks of climate change because it is our single largest source of carbon emissions-free electricity. Morgan has researched what the U.S. could do to get nuclear energy back on track, but all he’s come up with is bad news (or good news, depending on your point of view).

The age of the nuclear fleet is partly to blame. That’s not because America’s nuclear reactors are falling apart — they’re regularly inspected, and almost all of them have now gone through the process of renewing their original 40-year operating licenses for 20 more years, said David McIntyre, a public affairs officer at the U.S. Nuclear Regulatory Commission. A few, including the Turkey Point Nuclear Generating Station in Florida, have even put in for a second round of renewals that could give them the ability to operate through their 80th birthdays.

Instead, it’s the cost of upkeep that’s prohibitive. Things do fall apart — especially things exposed to radiation on a daily basis. Maintenance and repair, upgrades and rejuvenation all take a lot of capital investment. And right now, that means spending lots of money on power plants that aren’t especially profitable. Historically, nuclear power plants were expensive to build but could produce electricity more cheaply than fossil fuels, making them a favored source of low-cost electricity. That changed with the fracking boom, Morgan told me. “Natural gas from fracking has gotten so cheap, [nuclear plants] aren’t as high up in the dispatch stack,” he said, referring to the order of resources utilities choose to buy electricity from. “So many of them are now not very attractive economically.”

Meanwhile, new nuclear power plants are looking even less fetching. Since 1996, only one plant has opened in the U.S. — Tennessee’s Watts Bar Unit 2 in 2016. At least 10 other reactor projects have been canceled in the past decade. Morgan and other researchers are studying the economic feasibility of investment in newer kinds of nuclear power plants — including different ways of designing the mechanical systems of a reactor and building reactors that are smaller and could be put together on an assembly line. Currently, reactors must be custom-built to each site. Their research showed that new designs are unlikely to be commercially viable in time to seriously address climate change. And in a new study that has not yet been published, they found that the domestic U.S. market for nuclear power isn’t robust enough to justify the investments necessary to build a modular reactor industry.

Combine age and economic misfortune, and you get shuttered power plants. Twelve nuclear reactors have closed in the past 22 years. Another dozen have formally announced plans to close by 2025. Those closures aren’t set in stone, however. While President Trump’s plan to tell utilities that they must buy nuclear power has received criticism as being an overreach of federal powers, states have offered subsidies to keep some nuclear power plants in business — and companies like Exelon, which owns 22 nuclear reactors across the country, have been happy to accept them. “Exelon informed us that they were going to close a couple plants in Illinois,” McIntyre said. “And then the legislature gave them subsidies and they said, ‘Never mind, we’ll stay open.’”

So intervention can work to keep nuclear afloat. But as long as natural gas is cheap, the industry can’t do without the handouts.