Fourth Power vs ElevenLabs
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.
$500M Series D at $11B valuation (Feb 2026) — largest voice AI funding round ever. $330M ARR; 1M+ developers using the API. Enterprise customers: Deutsche Telekom, Revolut, Meta, Salesforce. Voices in 32 languages; real-time cloning from 1 second of audio.
About
ElevenLabs was founded in 2022 by Piotr Dabkowski and Mati Staniszewski, two former Google and Palantir engineers who set out to break the language barrier using AI voice technology. The company specializes in AI-powered voice synthesis, cloning, and dubbing, enabling developers and enterprises to generate human-quality speech in over 30 languages. Its core technology combines deep learning models trained on massive speech datasets to produce natural-sounding voices indistinguishable from real humans.\n\nElevenLabs offers a suite of products including its flagship text-to-speech API, voice cloning tools, and an AI dubbing platform that localizes video content while preserving the speaker's original voice. Its products target a broad audience—from indie developers building audio apps to large enterprises deploying voice interfaces at scale. Key differentiators include ultra-low latency streaming synthesis, fine-grained voice customization, and a growing library of pre-built AI voices across accents and styles.\n\nElevenLabs has grown rapidly, surpassing $330M in annualized revenue and serving over 1 million developers. Enterprise clients include Deutsche Telekom, Spotify, and leading media companies. In February 2026, the company closed a $500M Series D at an $11B valuation, cementing its position as the market leader in AI voice. Its APIs power podcasts, audiobooks, video games, and customer service bots worldwide, making ElevenLabs the default infrastructure layer for AI-generated audio.
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