Dishing out power with a solar engine

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But Infinia is staying clear of the wholesale power supply business because it's harder to compete with fossil fuel power on price, said Clyde.

Electricity generated from fossil fuels, such as coal or natural gas, is by far the most common form of power generation in the U.S. and is generally cheaper per kilowatt, according to solar industry executives.

"We wish Stirling Energy Systems all the success in the world because they're using a Stirling engine," Clyde said. "But if you can go after markets where (financial) incentives apply, you're not really competing against utility scale" pricing.

Besides planning to make a far smaller product, Infinia's generator will have a different design from those built by Stirling Energy Systems.

Infinia builds what is called "free-piston machines." This relies on changing air pressure to move motor components without having parts rub against each other. That design eliminates the need for lubrication and substantially cuts down on maintenance, Clyde said.

Combined heat and power
Infinia has been operating for over 20 years as a supplier of motors to government agencies for space and military applications.

Three years ago, the company reorganized itself to pursue potentially higher growth in the clean energy market, said Clyde. The company was chosen to present at the Cleantech Venture Forum in September and is seeking to raise funds to commercialize the solar Stirling product.

But solar electricity is only one application of the company's Stirling engines, said Clyde.

"With a Stirling engine, the thing that's great about it is that it only requires a heat source. It doesn't care what the heat source is," he said.

In the case of its solar Stirling product, the heat source is the sun. But the company is investigating a range of other applications and smaller models, which could be used to create electricity from biogas, such as methane, or used as on-board generators on tanks or trucks.

Already, Infinia has licensed its design for a combined electricity and home heating unit to manufacturers in Japan, the Netherlands and Germany.

Sized to fit under a kitchen counter, the units will use natural gas to fuel a Stirling engine that makes electricity. The process also creates hot water, which is used in water-based heating systems.

Infinia has individual homes in mind for its Stirling solar-electric products as well.

"I live on about two acres," said Clyde. "I can't wait to be the first on my block with one of these."

[Seaspray0]

Advantages over photovoltaic cells

The US residential house uses 120 VAC electricity but solar cells produce direct current (DC) voltage. This means you have to have an inverter to transform the electricity to a usable form for the house. The sterling engine can produce electricity at 120 VAC directly and also at 60 HZ which means the output can be fed directly into the power grid.

[alegr]

Invertor still necessary

Because the Stirling engine output depends on weather conditions, its RPM won't be stable, thus output voltage and frequency not stable, too. Therefore, and invertor (like those used in uninterruptible power supply) is still necessary.

[alegr]

Stirling A/C anybody?

Better use for the solar energy would be to drive an air conditioner. When one needs AC, sun shines the best, and the direct drive from an engine to the compressor can be used, without conversion to electricity.

[disco-legend-zeke]

Heat can run A/C directly.

Solar heat can generate cooling directly in an absorption cooler.

Remember? The propane operated refrigerator in your dad's camper.

Heat to heat is more efficient than driving a compressor.

[m.o.t.u.]

Stirling Engines

More good news on the energy systems.
I suspect mass uptake of solar energies will only become attractive to Mr & Mrs Suburbia when it's available at a Drive-Thru (their cars seem big enough to carry one}.
Cynicism aside, this is a very heartening article, great to see discussion on the potential of this technology.

[James Anderson Merritt]

Fuel cells are also 19th century technology

The fuel cell was first demonstrated before the 20th century, but was resurrected and pursued in earnest only when the US space program had a need for a "clean" power source with its characteristics. I don't care when a technology was invented. If it is an appropriate idea for today, let's use it.

[chuck_whealton]

Re: Fuel cells are also 19th century technology

I'll agree with you on that one. If it works, it works - and
hopefully it'll lead to bigger and better idea in the future.

Charles R. Whealton
Charles Whealton @ pleasedontspam.com

[jasred]

How about the Whispergen?..

http://www.whispergen.com/index.cfm

This device admittedly runs on natural gas fuel at the moment but I can't see why it might not be made to run from a solar concentrator. It is quite a neat New Zealand development of the Stirling cycle and is available now.

[MrHandle]

Good to See

It's good to see the proliferation of this technology. With advances in Plug-in hybrids etc..., we're laying the groundwork for a much cleaner, intelligent future. With improvements in metal, the Stirling engine has become much more practicle.

[chrisw63]

Such as Hydrogen??? <<--spin>>

Are you trying to put some negative spin on this story with that reference? Hydrogen would never be used in a Sterling engine. The seals required would be monstrously expensive, and the things hydrogen under pressure does to metal alone would preclude its use - too much maintenance. I can't believe a CNET reporter would be that inept.

Your negative spin won't work either, if anyone looks a little deeper. Those engines, even at that size, use barely enough gas to cause a small fire if there were an accident (and if it was flammable). They use it like an air conditioner, closed loop, and it is never burned. The efficiency of a Sterling engine is best when using a phase-change liquid, like a refrigerant. You'd have to keep hydrogen at some ungodly cold temperature, depending on pressure, to make it boil from liquid to gas in the Sterling loop - Yet another impracticality.

Could someone with a brain check these stories? Sheesh.

[columbus801]

Sheesh

A short literature and web-site search would indeed reveal that many Stirling engines use hydrogen and it is slippery to contain and often times requires a make up process to maintain performance (like a periodic refill). Also, not all Stirling engines are created equal, Kinematic versions (Solo, Kockems, STM, Dean Camen) have life, reliability and maintenance issues. The Free Piston varieties have been proven for long life and the Hellium versions are normally hermetically sealed for their long life, the reason most commercial focused programs are using Free Piston Stirling engines (Infinia, Rinnai, Enatec, Bosch)

[Michael Labay]

Here is another

http://www.acrosolarlasers.com/