Fourth Power vs Grok
Side-by-side comparison of AI visibility scores, market position, and capabilities
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.
About
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.
AI assistant by xAI (Elon Musk); Grok 3 topped reasoning benchmarks in Feb 2025; 1M+ paying subscribers in week one; real-time X post access; distributed via X Premium; xAI valued at $24B.
About
Grok is the AI assistant developed by xAI, Elon Musk's AI company founded in 2023, and distributed primarily through X (formerly Twitter). Grok launched in November 2023 as an X Premium perk, with the notable differentiator of real-time access to X posts and a less restricted, more direct conversational style. Grok 3, released in February 2025, achieved top scores on the AIME math reasoning benchmark and ARC-AGI test, briefly positioning xAI as a frontier model lab.
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