Japanese data center firm At Tokyo and Japanese waste heat to electricity firm elleThermo have successfully completed a demonstration project testing elleThermo’s waste heat to power conversion technology at a data center in Japan.

The demonstration project tested the effectiveness of elleThermo’s Semiconductor-sensitized Thermal Cell (STC) technology at two of At Tokyo’s data centers, the Chuo Center (CC1) and Chuo Center 2 (CC2), both loacted in Tokyo. The STC devices were installed in hot-aisle zones, air-conditioning mechanical rooms, and UPS rooms.

elleThermo’s STC technology works by converting low-temperature waste heat into electricity. Unlike conventional systems that require high heat or temperature differences, STC operates at around 30–40°C (86–104 °F), which it claims is typical of data center environments.

According to the companies, the results confirmed that power generation was achievable across all installation sites. The project also quantified performance variations based on environment and validated the feasibility of converting unused thermal energy from data centers into usable electricity.

The project was the first real-world validation test for elleThermo’s technology at an active data center site. Following the project, both companies have signaled their intention to further develop the technology to improve energy efficiency and reduce environmental impact, supporting broader sustainability goals.

At Tokyo operates around 13 data centers across the Japanese market, including facilities in Tokyo, Osaka, and regional hubs like Fukuoka and Sapporo. Its CC1 data center is its largest in the country, with a capacity of 70MW. The facility is part of a larger cluster that includes CC2 and CC3. CC3 was launched in 2024 and boasts a capacity of 40MW.

At Tokyo’s investors include Tokyo Electric Power (Tepco), Japanese security company Secom, and IT consultancy Intec.