Pumped Thermal Energy Storage

Active Energy is using its scientific expertise to help commercialize a new class of energy storage. Pumped Thermal Energy Storage is an economical, safe, and durable form of electricity storage great for long duration applications.


Oak Ridge National Lab is supporting the development of a first prototype


Active Energy is developing ice energy storage for pumped thermal thermal energy storage.

  • Charging: Electricity is consumed to freeze water

  • Discharging: Low temperature waste heat (<160°F) powers an engine that operates on a temperature difference, generating electricity and melting the ice in the process

With this system, commercial and industrial producers of low-grade waste heat will be able to generate electricity with the abundant amounts of heat they produce. Here is a short demonstration video:

The building on the left is a waste heat producer, such as a data center. The tank on the right represents an ice energy storage system. The black box in the center represents the engine running the pumped thermal storage process, alternatively generating and consuming electricity.