Patented engine design burns solid, renewable fuels

By | May 01, 2006
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Proe Power Systems LLC is putting a new "solid" twist on a not-so-new technology for stationary engines. The Proe Afterburning Cycle Engine is capable of taking in solid, renewable fuels like woodchips or sawdust. The patented design can burn virtually anything using solid, liquid or gas fuels to create combined heat and power, or distributed power generation—without gasification. "With this design, we sidestep gasification altogether," said Richard Proeschel, president and founder of Proe Power Systems. "It's an external combustion engine."

The Ericsson Cycle Engine, first developed by John Ericsson in the 19th century, is the basis for the Proe Afterburning engine, Proeschel told EPM. "We made simple modifications to the Ericsson engine," he said. "A slight change in the schematics really made big changes in its efficiency. We then made another simplification more recently," which is the basis for the company's newest patent.

The Proe Afterburning engine isn't a steam engine, but the principle is similar. Rather than using compressed steam (water), the engine runs on compressed air. Like a jet engine, Proeschel said the engine takes in air, which goes through a compressor. As the air gets compressed, it heats up and then goes through a heat exchanger, after which the hot, compressed air flows into an expander to push down a piston. The air expands and then is routed into the fire to fan it.

According to Proeschel, he got serious about developing this technology about 10 years ago. Then in 1997, after 32 years of experience with Rockwell International and Boeing—after Boeing bought out Rockwell—Proeschel founded Proe Power Systems.

In addition to being versatile, the engine-out exhaust is cleaner too. "The exhaust is so clean, it can run without any aftertreatment system," Proeschel told EPM. Although emission testing has yet to occur, Proeschel said it's not too far off. "We're building a prototype now, and we expect to have that complete by this summer," he said. "We'll complete the prototype and then take it to California (possibly the University of California, Irvine) to get bona fide, third-party independent testing."
Proeschel said a good rule of thumb for this engine's fuel input versus its electrical generation output is approximately one pound of wood for every kilowatt-hour. The engine is rated at between 50 to 60 horsepower.

There are already parties interested in this technology, like a yacht enthusiast looking for an auxiliary motor, for example, and others.

Proeschel believes the engine would be perfect for villages or remote areas isolated from electricity. Pumping water is another great application, which is how John Ericsson used his own engines nearly two centuries ago.