Stirling Revival | Green Energy News

November 20, 2005 – Vol.10 No.35

STIRLING REVIVAL.

While much of the attention for distributed micro combined heat and power (microCHP) systems has been focused on fuel cells, the other, probably cheaper, technology has been gaining ground and is very close to full-scale commercialization: Stirling engine powered microCHP systems.

Reverend Robert Stirling’s 1816 invention has already made headline news thanks to the hard work of Stirling Energy Systems in convincing California utilities Southern California Edison (SCE) and San Diego Gas and Electric (SDG&E) to buy at least 500 and 300 megawatts respectively of solar-thermal-energized, Stirling-engined generated power. Both agreements could grow to hundreds of megawatts of additional capacity.

The high-profile, full-scale commercial projects are sure to give Stirling technology, as well as solar energy, a boost in the marketplace.

But even before the Stirling solar dish project is built Stirling-engined home microCHP systems should be available.

Whisper Tech of New Zealand is already offering diesel fueled direct current (DC) WhisperGen microCHP systems for use in marine or remote, far from grid applications. Biodiesel could probably be used instead of petroleum diesel.

Inching closer to offering alternating current (AC) - WhisperGen systems for homes - the company has 400, one-kilowatt demonstration units being tested in homes in the U.K. The unit is the size of a dishwasher.

Given the high cost of natural gas one would think that a diesel version, running on biodiesel, could be made available for home use as well. (Save the bacon grease, it could be future fuel.)

Further, Microgen of the U.K. claims that full scale commercialization of its one-plus-kilowatt microCHP is set for 2007. The company’s technology has shrunk to the size of a kitchen wall cabinet with the first demonstration unit now installed in The Netherlands.

The unit makes electricity and hot water that can be used in heating systems or for domestic supply. The systems run at 90 percent efficiency on natural gas, but the company says a propane version should be available soon. (When propane (liquid petroleum gas -LPG) supplies get too tight a fuel called dimethyl ether - which can be made from a wide variety of sources - could feasibly take its place, but little work is being done in this regard at the moment.)

Now, along comes another company that claims it will begin manufacturing, marketing, and distributing microCHP systems: RINNAI Corporation, a maker of on-demand hot water systems. (Seems a perfect match: company moves from on-demand thermal energy to total home energy systems.)

RINNAI is not alone in the project. The Stirling engine technology will come from INFINIA (formerly Stirling Technology Company) of the U.S. and the microCHP integration will come from ENATEC microgen B.V. of The Netherlands.

The units are expected to have an overall efficiency of nearly 100 percent. Heat that isn’t used to make hot water will be used to make electricity. The units will run on natural gas and are expected to be sold in Japan in 2007, other markets, possibly the U.S., by 2008.

Like the other systems the microCHP will generate about a kilowatt of electricity, not enough, unfortunately, for U.S. homes at peak periods.

For those wanting the nearly 200-hundred year old technology now, a small, but useful, Stirling engine, energy-saving device is available for sale over the Internet - for $150.

The Thermal Engine Company of Madison, Alabama makes a Stirling engine-powered fan that sits atop a wood stove, the Heat Wave. Heat from the stove is the thermal energy that runs the device. (Stirling engines will run on any source of heat.) The turning shaft of the engine spins a fan which better distributes heat from the wood stove into the room at rate of up to 300 cubic feet per minute. Nifty and a little fun.

(One can imagine home heating systems that use a Stirling engine running off waste heat to operate blowers to distribute air or pumps to circulate hot water.)

Visit Stirling Energy Corporation at http://www.stirlingenergy.com/ Whisper Tech at http://www.whispertech.co.nz/ , Microgen at http://www.microgen.com/, Rinnai at http://www.rinnai.us/ , INFINIA at http://www.infiniacorp.com/ , ENATEC at http://www.enatec.com/ and the Thermal Engine Company at http://www.thermalengines.com/ .