Clean Power concentrating solar power meets Stirling Engine

Published on June 12th, 2014 | by Tina Casey


LNG Exports Bump Up Against Exportable Concentrating Solar Power

June 12th, 2014 by  

You knew we could not let another day go by without yet another article about concentrating solar power, right? This one has a bit of a twist. The Colorado-based company Cool Energy has just jumped into the global concentrating solar power market by hooking up its proprietary Stirling engine, which converts heat to electricity, with the concentrating solar power company Edisun Heliostats.

Since the Department of Energy has just come out with a new report estimating the methane leakage involved in exporting liquid natural gas from the US, now would be a good time to underscore the difference between exporting solar technology from the US, rather than incurring the risk, waste, local impacts, and greenhouse gas emissions from increasing our fossil fuel exports.

concentrating solar power meets Stirling Engine

Waste heat conversion courtesy of Cool Energy, Inc.

Cool Energy And Concentrating Solar Power

Cool Energy came across our radar in 2009 when it introduced its SolarHeart® Engine system. At the time, Cool Energy was marketing a home renewable energy package that combines solar input with waste heat capture.

The Stirling engine angle comes in right there. As a Stirling-type engine, SolarHeart operates by expansion and compression of air. The change in compression corresponds to different levels of temperatures, and the result is to convert heat energy to mechanical energy. A built-in generator converts the mechanical work to electricity and Bob’s your uncle (for more details, Ohio U. has a good backgrounder on Stirling engines.

Cool Energy has been expanding its market since 2009, one development being a $1 million Energy Department grant last year to develop a “GeoHeart” version to capture geothermal waste heat from oil and gas wells.

We’re not particularly thrilled about that application, but this new thing looks pretty neat.

Earlier this week, Cool Energy announced that it had signed on with Pasadena-based Edisun Heliostats to license its concentrating solar power system, which adds a lot more solar punch to the SolarHeart concept.

Edisun has designed its system around cost efficiencies, which nips away at the argument that CSP can’t compete with photovoltaic cells on price.

The company’s heliostats balance wind loading with an economical design, and Edisun claims that its “passive” particle-bed thermal energy storage system is more economical than other CSP alternatives such as molten salt.

Edisun also points out that its partnership with Cool Energy represents an additional efficiency, since Cool Energy’s Stirling engine is designed to run within a moderate temperature range.

Exporting Concentrating Solar Power

But, that’s not what we’re really interested in. Of special interest to us is that Edisun’s concentrating solar power (CSP) system is specifically designed to be trucked around in standard shipping containers.

Transportability is a huge issue for both solar and wind tech (for more on wind angle, see GE’s retro-styled, shippable “space frame” wind turbine towers), and breaking the system down into easily shippable components represents a huge cost savings.

In terms of this big push that’s on to increase natural gas exports from the US for the sake of energy security in Europe (think: bad Russia, bad!) perhaps it would make more sense to ship CSP systems and other renewable energy harvesting equipment around the world rather than continuing to increase the transportation impacts of fossil fuel pipelines as well as maritime, rail, and road transporation.


Here in the US we’ve had a string of high-profile environmental disasters related to fossil fuel transportation, and to that you can add the growing list of local impacts from natural gas fracking.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • JamesWimberley

    LNG supply chains can’t be improvised in a few months. You need to build a liquefaction plant at the export terminal (ballpark $20 billion – link) and a cheaper re-gasification one at the other, and a small fleet of specialised tankers ($250 million each – WSJ, link). To make these investments, you need long-term guarantees of supply and markets. There’s reason to think the US shale gas boom won’t be long-lived enough in this context. And the majors are getting nervous about the future costs of the renewable competition, which can easily put their $30 billion a pop underwater in 10 years’ time.

    • Matt

      Again a poor headline. The only “export” portion of the story is that they plan to make the setup fit in a standard shipping container. So something like “New CSP/Stirling combo fits in standard shipping container” and leave the LNG distraction out all together. LNG is NOT easy to ship.

      • Calamity_Jean

        So the “New CSP/Stirling combo” that “fits in standard shipping container” is competition for LNG shipping because it’s easier and likely to result in energy being available at the destination much faster than sending LNG there.

        • Ronald Brakels

          Yep, but solar panels are currently even bigger competition. Every solar solar panel Japan installs means they need to import less natural gas. And with an economic slow down looking increasingly likely in China their increased demand could be soon be entirely met with renewables, along with a small amount of nuclear power from plants that are already under construction. But if CSP can help eliminate fossil fuel use as well, that’s fantastic.

  • Make sure it’s cheaper and less complicated than this thing from Shell, a $12 billion LNG processing ship:

    I’m screwing up the copy/paste. The picture is a big ship. Like real big that sits far enough away from the shoreline to avoid some regulations.

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