IP: The Little Engine That Could Be: button size micro gas turbine

[David Farber <dave () farber net>]

> Date: Mon, 26 Nov 2001 23:00:04 -0800
> From: "Robert J. Berger" <rberger () ultradevices com>
>
> A little article thats technological and not too political :-)
>
> The Little Engine That Could Be
> By Louise Knapp
> http://www.wired.com/news/technology/0,1282,48400,00.html
> 2:00 a.m. Nov. 26, 2001 PST
>
> The development of a fuel-powered miniature engine, touted as a more
> efficient and longer lasting alternative for the battery, may push the
> Energizer Bunny to the unemployment lines.
>
> No bigger than a regular shirt button, the micro gas turbine engine
> uses the same process for producing electricity as its big brother
> electricity stations -- burning fossil fuel and running it through a
> power plant.
>
> "Fuel and air in, and electricity out," said Luc Frechette, assistant
> professor of mechanical engineering at Columbia University and one of
> the team members building the engine.
>
> At about one thousandth the size of a regular power station, the
> engine-on-a-chip will create about 1 millionth the power level,
> producing 20 watts of power at 2.4 million rpm from its cubic
> centimeter-sized package.
>
> "It will give 10 times the amount of power that is generated by the
> best lithium battery," Frechette said.
>
> And when the engine runs out of juice you just fill 'er up
> again. There's no need to wait to recharge or run out to the store for
> new batteries.
>
> "If you take a laptop battery for instance, it's just a bit bigger
> than a deck of cards. The engine would take up the space of, say, a
> quarter. The rest of the space would be for the fuel tank," Frechette
> said.
>
> "This fuel could last you for 24 hours and then, when empty, you can
> just refill the tank."
>
> Weighing less than a gram, the engine is constructed from eight wafers
> of diffusion-bonded silicon and consists of a combustion chamber that
> ignites hydrogen and shoots hot gas past a spinning turbine that
> powers the compressor to drive the machinery.
>
> The engine's tiny components -- the bearings, chambers and turbine --
> are precision etched onto the silicon.
>
> "We use the same miniaturizing technology that is used in the
> microchip industry," Frechette said.
>
> Building a complex 3-dimensional engine on such a microscopic scale is
> no mean feat.
>
> "We're pushing micro-fabrication to a new standard," Frechette said.
>
> One complication in developing components whose dimensions are
> measured in hundreds of microns is the difficulty in finding the right
> tools for the job.
>
> High speed rotating machinery requires high precision manufacturing to
> maintain tight clearance and good balance.
>
> To ensure that the millimeter-sized machines have the required
> fractional precision, the tools used to create them have to be made
> with the same exact precision -- one micron off and the resulting
> engine will be a non-starter.
>
> There's also the issue of stress.
>
> "The engine is a spinning man-made machine that goes at 2 million
> revolutions per minute. We don't know yet what kind of stress or
> problems this may have on the moving parts," Frechette said.
>
> These aren't the only challenges in building the engine.
>
> "When you scale things down you also create more friction, which
> results in more heat," Frechette said.
>
> This means that using a micro gas engine to power, say, your cell
> phone may mean you will feel your ears burn -- literally.
>
> "The engine generates a lot of heat. Burning fuel produces heat that
> needs to be evacuated -- this means it won't replace the battery in
> all applications," Frechette said.
>
> Once the problems of fabrication have been addressed, Frechette is
> confident that a complete system, with all the components in place,
> will be ready within the next year.
>
> Frechette believes the first buyers will be from the military.
>
> "The military are very interested in these. The small robots sent into
> the WTC rubble, for instance, had to be connected with cables to power
> them because their batteries are too heavy to carry," Frechette said.
>
> The micro engine would eradicate these problems.
>
> The commercial market will follow.
>
> "For commercial use, the first application will probably be a battery
> charger -- if not actually in a laptop it could sit beside it,"
> Frechette said. "Instead of having to get to an AC outlet, you can
> carry your power supply along with you."
>
> Representatives from battery manufacturers Duracell, Rayovac and
> Energizer were unavailable for comment.
>
> --
> Robert J. Berger
> UltraDevices, Inc.
> 257 Castro Street, Suite 223 Mt. View CA. 94041
> Voice: 408-882-4755 Fax: 408-490-2868
> Email: rberger () ultradevices com  http://www.ultradevices.com


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