Overview

• The Series A Plus totals $20 million led by Munich Re Ventures, with Breakthrough Energy Ventures and DCVC participating.
• Fourth Power is designing a 1 megawatt-hour demonstration and preparing its first full-scale unit while cycling smaller prototypes to verify output and durability.
• The system stores energy by heating carbon blocks and later pumps 2,400°C molten tin through graphite pipes, with thermophotovoltaic cells converting the heat to electricity in argon-sealed chambers.
• The company says typical operation would deliver eight or more hours of power with about 1% daily self-discharge from petroleum-coke insulation.
• Fourth Power projects long-run storage costs around $25 per kilowatt-hour and is targeting commercial deliveries in 2028.