24-hour Power Solar Heat Tech Gets $11.5 Million In Funding

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Terrajoule has closed an $11.5 million round of funding from several investors, including Air Liquide, a French multinational corporation and a world leader in the industrial gases business. NEA and two individual investors are also on board to help the Redwood City, CA solar and waste-heat energy storage start-up.



Terrajoule’s technology employs a steam engine design that has been used in American Navy ships. Using a steam engine might seem anachronistic, but parabolic solar troughs are utilized for generating the steam, which drives the engine in order spin a shaft to make a generator produce electricity.

The storage part of this energy production equation is a 30,000-gallon tank of hot water that is pressurized. This water can be turned rapidly into steam, which re-starts the electricity production when there is demand. No diesel fuel is used to run any part of their process
so there is no air pollution, and reciprocating steam engines have been described as much more efficient than steam turbines.

The California start-up was created to make solar power available at any time,

“Terrajoule was founded in 2009 to resolve the fundamental barrier to the widespread adoption of solar power as the most practical and economic source of new electricity generation for the 21st century. That barrier is intermittency, and the solution is to build energy storage into the systems that convert solar energy into electric power.” (Source: Terrajoule)

They say their approach to storing energy costs less than 20% of any form of battery storage.

Distributed power is what they envision for the future, so their systems range from 100 kW to 10 MW, with some larger ones as well. Modest investments for customers and and wide scalability are keys to their business model.

They say avoided expenses such as diesel fuel and electricity will result in a capital payback time of 2 to 5 years, and system life has been pegged at 25 years minimum. Their systems have zero emissions and are made of non-toxic materials.

The use of parabolic troughs combined with a steam engine and energy storage has been done before. In 1981 Australia’s White Cliffs Solar Power Station used 14 troughs and one steam engine.

Image Credit: Terrajoule

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Jake Richardson

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6 thoughts on “24-hour Power Solar Heat Tech Gets $11.5 Million In Funding

  • What sort of cost the Kwhour are we talking about here? This reminds me of the now bankrupt company (can’t recall the name) that was using similar sized dishes and couldn’t compete with PV.

    • $100/kWh. And very long cycle life.

      If this is for real then it’s going to be a player. Relatively cheap dispatchable power. It’s exactly what we need to fill in around wind and solar.

      • I see two costs here. The cost of gathering the heat, and the cost of storing it. [Not to mnetion the cost of the thermal to electrical conversion] This has to compete with other sorts of CSP with thermal storage. And against the use of natural gas peaker type plants, or hybrid plants, [nat gas supplemented by solar thermal]. Low temperature CSP sems to be losing out to the higher tech power towers with liquid salt storage. Are they capable of changing the relative economics versus towers enough to make this a go?

        I wouldn’t think a direct comparison against batteries (or other connected grid storage) is accurate, as this method can’t recharge from the grid, but can only recharge with solar inputs, so the average number of cycles per day is going to be lower than for grid storage systems.

  • It will be cheaper than any wind power very soon, below $0.05 per kilowatt hour before 2017. That is probably not as critical as the extremely low cost storage. Probable collectors, heliostats, troughs, CLFR and dishes. Perhaps ranked in that order, but scale dependent. Robert Mierisch, Founder and CTO of Terrajoule.

    • Wind is apparently already below 5c/kWh….

      “The prices offered by wind projects to utility purchasers averaged $40/MWh for projects negotiating contracts 2011 and 2012, spurring demand for wind energy.”



      $40/MWh means $0.04/kWh. Add back in the $0.022 PTC (which lasts only ten years) and it’s $0.051/kWh for a 20 year PPA.

      This is a low number. It’s not just the LCOE of wind. It includes real estate, transmission, taxes and wind farm owner profits. It’s the “delivered to the door” cost of electricity, not just the generation price. Taking all those factors into account the actual average generation cost is probably about 4c/kWh.

      That said, Terrajoule doesn’t need to reach 5c/kWh to be successful. What they seem to have is dispatchable electricity which is more valuable than either wind or solar for which the delivery time cannot be controlled.

      Terrajoule would initially be competing with gas peaker plants which often are able to sell their product well over 10c/kWh.

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