In a groundbreaking move to address the escalating energy demands of AI data centers, Exowatt, a solar-thermal startup backed by Sam Altman, CEO of OpenAI, is proposing an innovative solution using billions of hot rocks.
Reported originally by TechCrunch on November 13, 2025, Exowatt's technology harnesses concentrated solar power to heat rocks, storing energy that can be converted into electricity at an astonishingly low cost of one cent per kWh.
The Energy Crisis in AI Data Centers
The rapid expansion of AI technologies has led to an unprecedented surge in energy consumption, with data centers projected to quadruple global power demand over the next decade.
Traditional energy sources struggle to keep pace, often relying on fossil fuels that contribute to environmental degradation, while renewable solutions like wind and solar face scalability and consistency challenges.
Exowatt's Hot Rock Technology: A Game-Changer
Exowatt’s approach involves using solar energy to heat rocks to extreme temperatures, which then retain thermal energy for extended periods, providing a reliable power source even when the sun isn’t shining.
This method not only promises sustainability but also aims to drastically reduce costs, positioning it as a potential disruptor in the renewable energy sector for high-demand industries like AI.
Historical Context and Industry Impact
Historically, data centers have leaned on nuclear and gas-powered solutions, but lengthy development timelines and environmental concerns have pushed innovators to seek alternatives, as seen with Exowatt’s $120M Series A funding from investors like a16z.
The impact of such technology could redefine how tech giants like Google, Amazon, and Microsoft power their operations, potentially slashing their carbon footprint and operational costs.
Challenges and Future Prospects
Despite the promise, Exowatt faces significant hurdles, including the need to scale production to 1 million units per year to meet industrial demands, a challenge that could delay widespread adoption.
Looking ahead, if successful, this technology could pave the way for a new era of energy solutions, not just for AI but for other energy-intensive sectors, fostering a greener tech landscape by 2030.
Industry experts are cautiously optimistic, noting that while the concept of thermal storage isn’t new, Exowatt’s application and cost targets could set a new benchmark for innovation.
For now, the tech world watches closely as Exowatt moves to prove its vision, potentially transforming the intersection of AI and sustainable energy with every hot rock deployed.
Maria Lourdes
