Company Overview
About Fourth Power
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.
Business Model & Competitive Advantage
The system's physics promise costs 10 times cheaper than lithium-ion for grid-scale storage: graphite and tin are abundant, cheap materials, and thermophotovoltaics (solid-state, no moving parts) have lower maintenance costs than turbine-based thermal cycles. The 2,400°C operating temperature means extremely high energy density per unit volume — storing more energy in a smaller physical footprint than competing thermal storage approaches.
Competitive Landscape 2025–2026
Fourth Power's 2026 integrated demonstration is the critical de-risking milestone before commercial contracts, proving that graphite-to-tin heat transfer, TPV electricity conversion, and full system integration work together at representative scale. Breakthrough Energy Ventures' backing — Bill Gates' climate investment fund — provides both capital and access to the fund's network of climate-focused corporate partners who could become early customers.
Open Positions
Reddit Discussions
Key Differentiators
Emerging Innovator
Fourth Power is an emerging player bringing innovative solutions to the Climate Tech market.
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