Local green-energy firm helps NASA shoot for the stars

When NASA travels into space, Athens has got a hand in it, or at least an engine. The city of Athens is home to a world leader in engine technology and one of only a couple companies that can supply NASA with the engines it needs for missions into space.

Sunpower in Athens was incorporated in 1974 by former Ohio University professor William Beale, who invented the free-piston Stirling engine, now used for those missions and more.

"We make something that's called a heat engine in its very generic form," explained Mark Schweizer, president and CEO of Sunpower. "The novelty of it compared to what you might be used in a typical engine is that this takes any form of heat... We don't care what generates the heat. It could be the sun focused on a mirror pointed at the engine. It could be biofuels; if you want to use wood pellets, no problem. If you want to use natural gas, no problem, that works fine. Anything that generates heat can make the engine run, and then we combine it with a generator to make electricity."

Schweizer said that this is the novelty of the free-piston Stirling engine produced by Sunpower "“ it's fuel agnostic. "And at the same time, we tend to be very, very highly efficient," he said. "And not only are we highly efficient. We have unbelievable reliability."

He said one of the company's engines could run 100,000 hours, nonstop, without any maintenance.

"If you were to put that in perspective compared to your car, every 300 hours that your car runs, you need an oil change," he said. "So we can run something on the order of 10 years and never stop."

So the engines, Schweizer said, are highly efficient, very long-life, very reliable - and aren't picky about the source of heat used to power them.

"To date, most of our business is for NASA," he said. The company is in the process, he added, of attempting to make the technology more applicable in everyday life.

"What we're trying to do is take that same basic technology and apply it to terrestrial, more down-to-earth applications, where we could make electricity using the most efficient fuel source with the most efficient process," he said.

The company currently has a licensee, according to Schweizer, using the technology to produce electricity for homes in a 1-kilowatt engine that simultaneously uses excess heat from the engine to heat water in the home. "So the system efficiency is very high," he said.

Remote areas that need reliable energy are another area Schweizer said the technology at Sunpower could play an invaluable role. He pointed to cell-phone towers that might be built on a hill that is difficult to reach as an example, or compressor stations along a natural-gas pipeline.

"Some of these things can be way out in the wilderness, where, if you have a problem, refueling and maintenance can cost you a fortune just because of sending somebody out there," he said. "So the next area we're really looking at are remote power applications. And then a little bit longer down the road, we're trying to find the right spot where solar energy makes sense."

While Sunpower has competitors who are trying to make utility-scale applications, Schweizer said he's not sure if that's the best use of the technology at this time, though it's possible.

The key challenge, he said, is getting the technology to a point where it's cost effective.

"When we've been making them for space, nothing matters more than not having failure, because the cost of a scrubbed mission is unbelievable, so everything else pales in comparison," he said. "But when you're thinking about using this for your choice as using a gas turbine or diesel generator, we have to be cost competitive and that's what we're working on now."

What sets Sunpower apart, Schweizer said, is the free-piston technology. The technology uses springs to allow a natural bounce in the engine that doesn't require lubrications to allay heat concerns.

"So when I talk to you about an engine that can run 100,000 hours, it's precisely because of that," Schweizer said. "It's because it doesn't have to have lubrication. It is what allows this system to be so robust and reliable... For space, you would never thing about using a Stirling that wasn't a free-piston; it would be unimaginable."

Sunpower's intellectual property portfolio includes more than 39 U.S. patents and 97 related foreign patents. The U.S. government has awarded Sunpower 30 small-business research grants, and the company offers a range of services to industrial, educational, laboratory and government clients.

This past June, Sunpower celebrated its 35th anniversary, which makes is Athens' first and oldest green energy company.