Innovation Spotlight: Waste Heat Recovery Using the SolarHeart Stirling Engine

November 21, 2012 08:07 PM EST By: Regina Ramazzini

Asia Pacific Clean Energy Summit Innovation Tracker: Cool Energy, a TechConnect Accelerator participant-Honolulu, HI, 2012

Cool Energy has developed the SolarHeart® Engine, an innovative and pioneering Stirling engine that converts low temperature heat energy into electricity. This SolarHeart Engine sets itself apart from other Stirling engines with its use of lower heat input engine temperatures (100°C to 300°C). While some competing technologies work in the same range, they are typically for much higher power uses.
Applications such as waste heat recovery, solar thermal electric, and biomass power are enabled by the SolarHeart Engine’s output power ranges of 3kW and 20kW. The SolarHeart Engine’s primary market, due to its rapid payback time, is electricity-producing recovery of waste and exhaust heat.

Cool Energy was a welcome participant at the Asia Pacific Clean Energy Summit’s Defense Energy Technology Challenge (DETC) in Honolulu, HI. With collaboration from the U.S. Army, Navy and Air Force, DETC delivered many of the top defense-targeted clean energy solutions, matching with different test and procurement opportunities. Cool Energy was a finalist among the more than 250 high quality submissions that the program received.

TechConnectNews spoke with Sam Weaver, CEO at the company.  He told us that what he found most valuable about the DETC program was “The ability to meet the actual representatives of the military that know what the needs and requirements are, and the opportunity for a small company like us to meet some of the other suppliers to the military.”

A few noteworthy happenings since the event for Cool Energy: 1) they were able to commission their first customer unit in October: Schneider Electric of France. Schneider is currently performing testing of that unit, looking for both reliability and performance. 2) They have set a power conversion record of 22% thermal to electrical efficiency at 300°C, and 3) they demonstrated a maximum output power of over 3200W.

Mr. Weaver told us that they are currently in fundraising mode in order to roll out of their products. The design is complete, is in reliability testing, and has 1000 hours of operation on each of their two prototype engines. The engines are running 24/7 and are periodically disassembled to look for signs of wear. At the same time, they are increasing their business development and trying to get the technology licensed to manufacturers in India and in Europe.

For more information, please visit their website at or visit for their introductory video. 


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