Stirling-Cycle Engine Generators

September 24, 2012| Engines|3 Minutes|By AAG

Sunpower unveils the Microgen Combined Heat and Power (microCHP) system, an innovative electrical co-generation unit scheduled to hit the European consumer market through British appliance distributor Microgen, Inc. The Microgen system is powered by natural gas and utilizes a free-piston Stirling-cycle engine to generate both a kilowatt of 50hz electrical energy in addition to home water-heating for domestic cooking & home-heating systems.

The Sunpower/Microgen marketing strategy is to target residential homes in Western Europe currently utilizing natural-gas fired boilers typically mounted on a kitchen cabinet The high-reliability and low operating noise of the Microgen free-piston Stirling cycle design allows the company to replace these boilers with a co-generation unit featuring both the low-noise and high-reliability of a kitchen refrigerator, while additionally producing a kilowatt of direct electrical energy and complete home-water heating needs.

The Microgen system takes a unique approach to generating electricity, as a pressure-waves in liquid drive the Stirling-cycle piston through an alternator to produce current. The pressure wave itself is created by a large temperature differential when the gas-flame heats the top of the Stirling engine while the bottom of the engine is cooled by an incoming water-return from a radiator system. Thus, the device is essentially powered by waste-heat redirected for water & radiative heating, which in turn sets up the required pressure-differential to power the electrical generation unit.

Our 3-minute interview takes place during the device’s first public showing at STAIF, where we get a rare cutaway-view of the internal components and an engineering overview in what’s next in free-piston Stirling-cycle technology. The technology itself is flexible and scalable enough to allow future versions of the device to run on oil, liquid petroleum gas, and a variety of other fuels. The final selling point for this technology is it’s compliance with Kyoto environmental-treaty regulations — with the claim that if every home in the UK utilized this new Microgen Stirling cycle technology, it could contribute to as much as 25% of the UK’s required Kyoto-treaty obligations.