Raised $45M total including $20M Series A (Munich Re Ventures, DCVC, Breakthrough Energy). Integrated demo unit completing 2026. Targets 10x cheaper storage than lithium-ion.
Fourth Power is an MIT-originated thermal energy storage company that stores electricity as heat in graphite blocks at 2,400°C — using molten tin as a heat transfer medium and converting stored heat back to electricity via thermophotovoltaics (TPV). The company has raised $45 million including a $20 million Series A from Munich Re Ventures, DCVC, and Breakthrough Energy Ventures, and is completing its full integrated demonstration unit in 2026.
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