Sam Atlman-backed Exowatt wants to power AI data centers with billions of hot rocks

Hannan Happi, co-founder and CEO of Exowatt, has set his sights on addressing the pressing energy demands of AI, driven by a singular goal: achieving a cost of one cent per kilowatt-hour. "We explored various configurations and designs," Happi shared with TechCrunch. "Each variant offered unique insights into reducing costs and enhancing efficiency." The company’s initial offering is an innovative energy solution, resembling a shipping container with a transparent top. Inside, a straightforward yet effective system operates. If Exowatt succeeds in delivering around-the-clock solar energy at a minimal cost, it could significantly disrupt the data center sector and the energy landscape at large. To accelerate its production towards this ambitious one-cent target, Exowatt has secured an additional $50 million, building on a previously closed $70 million Series A funding round. This extension was spearheaded by MVP Ventures and 8090 Industries, with contributions from various investors, including Sam Altman and Andreessen Horowitz. Happi noted that despite not initially planning to raise more funds after April, the strong market momentum and investor interest prompted the decision to seek additional investment. Currently, Exowatt boasts a backlog of approximately 10 million P3 units, equating to a capacity of 90 gigawatt-hours. Happi expressed a clear vision: "Our aim is to scale production to millions, eventually reaching billions of units. We anticipate meeting our one-cent target when we produce around one million units annually." Exowatt’s technology, known as concentrated solar power, has been around for decades. It harnesses solar energy to heat materials that effectively store or transport thermal energy, often referred to as “rocks in a box.” Each P3 unit comprises a metal box fitted with lenses that concentrate sunlight onto a special brick, generating heat that is then used to drive a Stirling engine connected to a generator. The design emphasizes simplicity, with each thermal battery capable of retaining heat for up to five days, ensuring consistent energy supply. By combining multiple P3 units, customers can tailor their electricity generation to meet specific demands. Happi asserts that the system's efficiency rivals that of traditional photovoltaic solar panels and even outperforms them when paired with lithium-ion batteries. While other companies have attempted similar technologies, many have struggled to compete with the rapidly decreasing costs of photovoltaic solar and lithium-ion batteries. However, Happi believes that Exowatt's modular design and their methodical approach to scaling manufacturing will set them apart. Globally, there are over 100 solar thermal projects at various stages, which pales in comparison to the annual production of 1.5 billion solar panels. This disparity highlights the potential for Exowatt to leverage manufacturing efficiencies. Despite some limitations, such as the need for substantial land and optimal sunny conditions, Happi remains optimistic. He points out a significant overlap between the ideal locations for Exowatt’s P3 systems and the sites of emerging data centers, ensuring a steady pipeline of projects ahead.