A U.K. startup backed by China’s Tencent Holdings Ltd. proved a novel approach to generating fusion energy in a breakthrough that could slash the technology’s cost by providing cheap, clean nuclear fuel. First Light Fusion Ltd. is among about two dozen startups trying to harness the power that makes stars shine. Some focused on building machines that hold fused atoms together, while the Oxford-based company concentrated on the fuel elements that catalyze the reaction. First Light used a hypervelocity gun, which engineers call their “Big Friendly Gun,” to fire a projectile at 6.5 kilometers (4 miles) a second into a fuel target to generate energy. Each thimble-sized target, which is heated and compressed at extreme density, could release enough energy to power an average U.K. home for two years, the company said. “We have identified a genuine route to commercial fusion,” First Light Chairman Bart Markus said in a […]