China taps high-altitude winds for power generation with flying craft at 4,000m

Beijing start-up Sawes Energy Technology, collaborating with Tsinghua University, flew the S4000 prototype—a helium-filled craft roughly the length of a Boeing 747 carrying turbines—to 4,000 metres above sea level in northwestern China and completed a full work cycle of ascent, power generation, and recovery. The S1500 model reached 1 megawatt output in September 2025; the S2000 in January 2026 had drawn orders worth 74.3 million USD as of March.