# 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.

- **Founded:** 2009
- **Headquarters:** Palo Alto, California, United States
- **Founders:** Stephen J. Bisset (Founder & CEO)
- **Team size:** Small (roughly 2 employees per public listings)
- **Products:** Dispatchable Solar Module (DSM), Steam Accumulator Energy Storage (SAES), Prefabricated Solar Concentrator (PSC), Modular Solar Power Station
- **Notable:** Raised $11.5M Series A from NEA and Air Liquide's ALIAD., Built and operated a 100kW 24/7 solar prototype near Modesto, California (operational December 2013)., Developed a patented Dispatchable Solar Module (DSM) storage architecture using steel and water instead of lithium.

## Products & services

- **Dispatchable Solar Module (DSM)** — Terrajoule's patented solar-plus-storage building block - a modular unit that generates and stores solar energy to deliver electricity 24/7 at a fraction of the cost of lithium-ion batteries, built from steel and glass with globally available manufacturing capacity.
- **Steam Accumulator Energy Storage (SAES)** — Energy storage that condenses steam into a mass of pressurized hot water held in insulated steel pressure vessels, then flashes it back to steam on demand - a steam-water-steam phase-change loop with under 2% energy loss and no rare or toxic materials.
- **Prefabricated Solar Concentrator (PSC)** — A factory-built Linear Fresnel solar concentrator optimized for automation, shipped in standard containers for onsite assembly - claiming a 3:1 installed cost reduction and a 10:1 reduction in installation labor versus conventional concentrators.
- **Modular Solar Power Station** — Modular 2MW solar power stations combining concentrators, storage and steam piston engines to dispatch clean energy up to 24 hours per day, scalable from distributed to utility deployments.

## Achievements

- Raised $11.5M Series A from NEA and Air Liquide's ALIAD.
- Built and operated a 100kW 24/7 solar prototype near Modesto, California (operational December 2013).
- Developed a patented Dispatchable Solar Module (DSM) storage architecture using steel and water instead of lithium.
- Demonstrated a steam-water-steam storage cycle with under 2% energy loss and ~98% storage/retrieval efficiency.
- Claimed storage capital cost under $100/kWh - roughly 5x cheaper than equivalent battery storage.
- Acquired by Environmental Clean Technologies Limited in December 2025.

## Latest updates

- **2025-12** — Terrajoule acquired by Environmental Clean Technologies Limited (ECT) to scale its patented DSM solar-plus-storage technology.
- **2022** — Relaunched as Terrajoule Energy Inc., advancing the Dispatchable Solar Module (DSM) and Prefabricated Solar Concentrator (PSC) toward pilot-plant engineering and construction.
- **2013-12** — 100kW 24/7 field prototype operational near Modesto, California, validating steam-accumulator storage.
- **2013-11** — Closed $11.5M Series A led by NEA with Air Liquide's ALIAD.

## Links

- Website: https://terrajoule.energy
- LinkedIn: http://www.linkedin.com/company/terrajoule

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Profile page: https://yespress.io/terrajoule-energy-inc
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Last updated: 2026-07-10