Stirling Biopower develops new electrical generator

By Erin Voegele
Web exclusive posted Nov. 7, 2008 at 11:12 a.m. CST

Stirling Biopower, an Ann Arbor, Mich.-based company that designs, manufactures and sells electrical generators, announced Nov. 5 its FleXgen electrical generator is now available for commercial sale. Rated at 43 kilowatts, the FleXgen uses renewable fuels in a wide variety of distributed generation applications.

Unlike competing products, the FleXgen features an external combustion engine, similar to what is found in a furnace or boiler. Fuel feeds a constant flame, which heats hydrogen gas without combusting it. The heated gas expands, causing a piston to move, which turns a generator and makes electricity. Cooled hydrogen gas is then reheated by the flame, and the cycle repeats. According to David Miklosi, Stirling's vice president of sales and service, the FleXgen offers a variety of benefits to the consumer.

"[The product] can take a wider variety of fuels," Miklosi said. "It is able to take fuels that are a little more contaminated or dirty than others." For example, the engine can burn fuel containing siloxanes that normally require expensive removal before the gas can be used in internal combustion or microturbine engines. According to Miklosi, siloxane is particularly troublesome in waste water treatment plants.

In addition, the FleXgen produces low emission levels and has a low fuel pressure requirement of 2 psi. It can also be used in combined heat and power applications and has low instillation and maintenance costs. Due to the fact that it's scaleable, small- and medium-sized landfills can utilize the generator to produce electricity from methane gas which has traditionally been flamed. Untreated methane gas from waste water treatment facilities can also utilize the product. "The [FleXgen] is the result of more than thirty years of research and design," Miklosi said. "We have about 250,000 test hours on this engine technology."