Cleantech startups develop new thermal energy storage methods

New cleantech developments are emerging to address the seasonal storage of renewable energy. In the United States, the startup Standard Thermal is testing a thermal earth storage system in Oklahoma. Unlike traditional silo-based sand batteries, this method uses an earthen mound to store solar power as heat. The process involves using electrical resistance heaters to warm air, which is then circulated through the mound. The system reportedly achieves a total thermal efficiency of over 90 percent and aims to provide industrial customers with heat more affordably than natural gas.

In Switzerland, the company Season is piloting a thermochemical storage technology designed to bridge the gap between summer solar production and winter heating demands. This system utilizes sodium hydroxide and water stored in separate tanks. During periods of excess solar energy, water is evaporated from the sodium hydroxide solution and stored separately. In winter, the process is reversed: the stored water is reintroduced to the concentrated solution, triggering an exothermic reaction that releases heat for residential or industrial use.