Silicon Valley’s Peter Thiel’s Other Hobby Is Nuclear Fusion

A unit manager leads a tour inside the Unit 2 cooling tower, then under construction, at the Watts Bar Nuclear Plant near Spring City, Tennessee, on April 29, 2015.

Photographer: Mark Zaleski/AP Photo

U.S. President-elect Donald Trump has angered clean-energy proponents by making false statements about climate change and promising to expand fossil-fuel exploration—a policy that could further exacerbate the existential threat he’s claimed is a Chinese hoax. Wouldn’t it be ironic then if there was someone deep in Trump’s confidence who’s made a bet on cleaning up energy technology once and for all?

Nuclear fusion, which would harness the power of the sun without all the nasty byproducts, is a long-shot—politically, financially, and technologically. Despite relative ambivalence toward fusion by the Obama administration, research has continued apace internationally, and in the American public and private sector. At the head of this pack ...