By Jenny Neill
Cool Energy is teaming up with Diedrich Manufacturing Inc. to find coffee roasters to pilot test the ThermoHeart Engine.
Diedrich Manufacturing Inc. unveiled a new marketing partnership at this year’s Specialty Coffee Association of America conference and exhibition. Sam Weaver, c.e.o. of Cool Energy, explained how the companies first got connected: “About four years ago, Steve Deidrich heard that we were working on heat recovery technology and came to visit. Then, [two years ago], Mike Paquin, who is now c.e.o. of Deidrich, came to visit and we showed him what we were working on.” That visit led to establishing a co-marketing relationship to evaluate how the two companies’ equipment might work together.
Cool Energy’s ThermoHeart “Sterling” Engine relies on a thermodynamics cycle involving the expansion and compression of air or other gas which then spins a permanent magnet alternator to produce electricity. This type of closed cycle system was invented in the early 19th century by a Scottish minister by the name of Robert Stirling, for which this type of engine is named.
Adding the ThermoHeart Engine to a coffee roasting facility makes sense because of the large amount of hot gas produced when an afterburner or other oxidizer technology is used to destroy pollutants. Exhaust gases reach temperatures of 800 to 1200°F and can be run through an external heat exchanger. This is the function the ThermoHeart could serve in a coffee roasting facility.
The energy recovery and return-on-investment will vary depending on the costs of electricity. Weaver stated, “if you’re in Hawaii where you pay 40 cents a kilowatt-hour, you might see payback times under two years. If you’re in California you might see payback times of four years and if you’re in some place like Arkansas you’re going to see payback times of 8 or 9 years.”
The early prototypes of Cool Energy’s engine had about a 5% conversion efficiency. After Weaver and his partners tried marketing their design to a home consumer market, they realized that they might meet with more success if aiming for a more industrial market. The team continued to refine and test units, first increasing size and power capacity from the 50-watt table-top demo model to the 3-kilowatt version on display in the Diedrich booth at the SCAA Expo. According to Weaver, Cool Energy is ready to move ahead with pilot testing 20-kilowatt units in a coffee roasting setting.
He said, “[We] are looking for partners who are in [coffee roasting] operations that run 24/7 or something like 24/7, who are in footprints with high electricity costs.”
He went on to add, “the nice thing about the 20-kilowatt unit, it’s seven times the power but only two and a half times the cost of the 3-kilowatt unit. So it’s got a much better customer value proposition.”
Information on the company’s website suggests an initial market price of $55,000 - $60,000 for the 20-kilowatt ThermoHeart.