In his year-end letter, Microsoft co-founder Bill Gates says his to-do list for 2019 includes persuading U.S. leaders to regain America’s leading role in nuclear energy research and embrace advanced nuclear technologies such as the concept being advanced by his own TerraPower venture.

“The world needs to be working on lots of solutions to stop climate change,” Gates wrote in the wide-ranging letter, released Saturday night. “Advanced nuclear is one, and I hope to persuade U.S. leaders to get into the game.”

Gates acknowledged that tighter U.S. export restrictions, put in place by the Trump administration, have virtually ruled out TerraPower’s grand plan to test its traveling-wave nuclear technology in China.

“We had hoped to build a pilot project in China, but recent policy changes here in the U.S. have made that unlikely,” Gates wrote. He said “we may be able to build it in the United States” if regulations are updated and the investment climate for nuclear power improves.

Bellevue, Wash.-based TerraPower struck a deal with China National Nuclear Corp. back in 2015 to build the plant, with the aim of demonstrating the feasibility of fourth-generation traveling-wave nuclear reactors, which are designed to use depleted uranium as fuel and minimize waste. At the time, TerraPower said the plant could be built by 2022.

Last year, a consortium of five Chinese nuclear power companies said 1 billion yuan ($153 million) would be set aside for technology development.

Experts had predicted that the Trump administration’s export limits were likely to put a crimp in TerraPower’s plans for the China project.

In November, Morning Consult quoted TerraPower’s chief financial officer, Marcia Burkey, as saying that October’s announcement of the new export restrictions caught the company “by complete surprise.”

In his letter, Gates wrote that nuclear power had to play a greater role in America’s energy mix due to concerns about climate change. He noted that global emissions of greenhouse gases have resumed their upward trend. “For me, that just reinforces the fact that the only way to prevent the worst climate-change scenarios is to get some breakthroughs in clean energy,” he said.

Gates said power planners should take advantage of renewable energy sources such as solar and wind power “wherever it makes sense.”

“But solar and wind are intermittent, and we are unlikely to have super-cheap batteries anytime soon that would allow us to store sufficient energy for when the sun isn’t shining or the wind isn’t blowing,” he wrote. “Besides, electricity accounts for only 25 percent of all emissions. We need to solve the other 75 percent too.”

Gates and other industry leaders, including Amazon founder Jeff Bezos, have been funding a wide variety of clean-energy innovations through Breakthrough Energy Ventures, a $1 billion investment fund. “The companies we chose are run by brilliant people and show a lot of promise for taking innovative clean-energy ideas out of the lab and getting them to market,” Gates wrote.

But he insisted that nuclear power was needed as well:

“Next year I will speak out more about how the U.S. needs to regain its leading role in nuclear power research. (This is unrelated to my work with the foundation.) “Nuclear is ideal for dealing with climate change, because it is the only carbon-free, scalable energy source that’s available 24 hours a day. The problems with today’s reactors, such as the risk of accidents, can be solved through innovation. “The United States is uniquely suited to create these advances with its world-class scientists, entrepreneurs, and investment capital. “Unfortunately, America is no longer the global leader on nuclear energy that it was 50 years ago. To regain this position, it will need to commit new funding, update regulations, and show investors that it’s serious.”

The United States still ranks as the world’s largest producer of nuclear power, with 98 operational reactors generating total net electrical capacity of nearly 100,000 megawatts, according to figures from the International Atomic Energy Agency’s Power Reactor Information System. France ranks second with 58 reactors, and China comes in third with 46.

However, the future for nuclear power looks quite different: The World Nuclear Association reports that 13 new reactors are currently under construction in China, compared with just two in the U.S.