Monday, March 10, 2008

ReGen's Stirling idea: Power from waste heat

By Efrain Viscarolasaga

In many manufacturing processes, waste heat is just that -- wasted. But a company in central Massachusetts has developed a way to turn that wasted (and free) heat into power using a centuries-old technology principle.

Last week, the Massachusetts Technology Collaborative jumped on board with the company, providing a $500,000 loan to help the company build its first beta test unit in the Bay State.

Dick Meloy and Ricardo Conde, the founders of ReGen Power Systems Inc. of New Salem, plan to apply their modified Stirling engine technology to industrial power generation, creating a generator capable of producing between 250 kilowatts and 2.5 megawatts of power using only waste heat as fuel.

The principles of the Stirling engine have been around since 1816, when Robert Stirling first demonstrated a device that could move a piston based on the changes in air mass created through a variation in temperature. The result is a quiet, efficient engine, but one that needs drastic temperature changes (in the hundreds to thousands of degrees) and takes up a lot of space. Such requirements have limited modern Stirling designs to niche applications such as in submarines.

ReGen's proposed unit can work at temperatures as low as 390 degrees -- and that is what makes its unit unique, said company managing director Meloy. "There are no exotic materials here, it's strictly the design that is the secret sauce," he said.

Operating at 480 degrees, the unit is capable of converting about 25 percent of the waste heat into power, according to Meloy.

"Twenty-five percent sounds small, but when you're not burning any fuel to get it, the economics become pretty attractive," said Meloy. "We think, depending on what a site is spending on electricity, the unit will pay for itself in two to two-and-a-half years."

Given the number of manufacturing processes that generate or use heat, the U.S. market for waste-heat energy generation could be in the billions of dollars, according to Meloy and MTC officials.

While it was not a stipulation of the funding, ReGen has agreed to deploy the first unit in Massachusetts, according to Sissy Liu, who is an industry investment and development manager for the Renewable Energy Trust, which is managed by the MTC. A site has not yet been chosen, but ReGen is working closely to place the first test with a European manufacturer with a factory in Worcester. If that site does not work out, however, Meloy has vowed to keep the project in the state at another facility.

ReGen is not the only company looking at incorporating Stirling principles into modern technology. Another local company, Precision Combustion Inc. of North Haven, Conn., has been working for over a year with the U.S. Army on a catalytic burner for Stirling engines to be used in portable power applications. And at this week's CeBIT computer show in Germany, Taiwan computer component maker Micro-Star International unveiled a chipset cooler for computers that is based on the Stirling engine.

Executives at both ReGen and the MTC think that if their project is successful, it could move the Stirling engine from a little-known engineering niche to a common alternative energy option.

"(The Stirling engine) hasn't been extremely successful in the past, but if this is successful, I think you'll be hearing more about Stirling engines in the future," said Liu.