Terrajoule Energy Inc

Terrajoule Energy is a Palo Alto cleantech company building modular, dispatchable solar power stations that deliver clean electricity around the clock without lithium-ion batteries. Its patented Dispatchable Solar Module (DSM) pairs prefabricated Linear Fresnel solar concentrators with a Steam Accumulator Energy Storage (SAES) system - storing energy as pressurized hot water in steel pressure vessels - and reciprocating steam piston engines to turn steam into electricity. The pitch is blunt: store energy in steel and water instead of rare metals, and undercut the cost of PV-plus-battery from day one. Founded by electrical engineer and serial hardware entrepreneur Stephen J. Bisset, Terrajoule raised an $11.5M Series A from NEA and Air Liquide's ALIAD, and was acquired by Environmental Clean Technologies Limited in December 2025.