Breakthrough Energy Backs 21 Startups in Sixth Fellows Cohort

Bill Gates' Breakthrough Energy unveiled its sixth Fellows cohort on Sept. 22, 2026, backing 21 early-stage startups spanning fusion power, semiconductors, hydrogen transport, agriculture and climate adaptation. Eric Toone, managing partner at Breakthrough Energy Ventures, said data centers represent "a 10% bump" against flat electricity demand but signal a coming surge. "Electrifying everything implies a 3x increase in demand for electricity," he said. The cohort includes Borealis Fusion, a proton-boron fusion developer, and StarWarden, which works on reactor heat management. Bedrock Semiconductor, K1 Semiconductor and Vari Flux target data center and power-electronics efficiency; Gaddy said K1's materials processing could cut power-electronics costs by 50% or more. Additional bets include AmyHyTech and Ammovolt Energy, which use ammonia to transport hydrogen, plus ocean-floor mineral harvesting and crop-disease sensing startups. The cohort is the first since Ashley Grosh's departure to WovenEarth Ventures; Benjamin Gaddy serves as acting director.