China is set to more than triple its nuclear energy capacity over the next 20 years, overtaking the U.S. to become the world’s largest nuclear-power producer, according to the International Energy Agency.

Speaking at the International Petroleum Week conference in London on Wednesday, IEA Executive Director Fatih Birol expressed concerns that the U.S. and Europe aren’t investing enough in nuclear power, while China is charging ahead.

“China is coming back strong. Today there are about 60 nuclear power plants under construction and more than one third of them are in China. China is growing and as a result of that we’ll soon see China overtaking the United States as the number 1 nuclear power in the world,” he said.

He noted that the U.S. has been the global leader in nuclear power since the 1960s, but said that two trends are threatening to knock the country out of the top spot: Very few additions to nuclear capacity and no lifetime extensions for the existing power plants. The same goes for Europe, he said, where major nuclear player France has seen output decline sharply in recent years.

“If it continues like that, the U.S. nuclear capacity will go from 20% [of overall power supply] to 7%,” Birol said.

“This has many implications in terms of energy. I can tell you that what is happening is the same story as we’ve seen in solar. [China] is learning by doing, bringing costs down and therefore [they] are now ready to export [their] technology and are much more cost effective than others. And [they] challenge the established exporters such as the U.S., Japan, Korea and European countries,” he said.

Fatih expects China to overtake the U.S. as the biggest nuclear nation by 2030, as shown in this chart below.

International Energy Agency

China’s push into nuclear power comes as the country changes course from being an economy focused on rapid, manufacturing-based growth to lift the masses out of poverty, to a more service-based economy with a stronger focus on clean energy. This narrative further gained support last year when Premier Li Keqiang pledged to make the country’s smoggy skies “blue again.”

The IEA expects the nuclear power capacity in China to make up 4% of the country’s total power supply in 2040, up from 2% in 2016, according to data on the agency’s website. Overall power supply across all energy sources is expected to double from 1,625 gigawatt in 2016 to 3,188 GW in 2040. That means nuclear capacity is forecast to more than triple from 32.5 GW to 127.52 GW.

International Energy Agency

Birol also identified China’s drive to make the skies blue again as one of four “major upheavals” that will reshape the energy markets in the coming decades.

“I will give you an example... Only five months ago the Chinese government took a decision to limit the use of coal and move to [liquefied natural gas]. As a result of that, Chinese LNG import increased more than 50% and LNG prices doubled from $6 to $12 dollars in Asia pacific region,” he said.

“When China changes, everything changes... The new China energy policies mean a new phase for the global energy markets,” he added.

The three other major upheavals laid out by Birol were U.S. oil and gas production, solar power and the “electrification of our economies.”