Segways Dean Kamen's next invention the new sterling engine.

[IChing]

Segway inventor Dean Kamen has spent roughly US $40 million developing his next passion project, the Stirling engine. A Stirling is different from a typical internal-combustion engine in that it's "closed-cycle"; while it still uses expanding gas to drives pistons, it's completely sealed, emitting nothing. The gas stays inside, expanding and contracting when needed.

Kamen's version of the engine generates spare electricity and runs on, well, anything. Two of his prototypes are currently providing power to two Bangladeshi villages, using cow manure (you read that right) as fuel.


"Say you're in Bangladesh or anywhere in the world where people don’t have electricity," says Kamen, dusting himself off and not missing a beat. "You get home and you plug your house into it." He shows off power plugs behind the scooter's seat. "It’s your power system, it’s your heating system, it gives everybody electricity. When you leave in the morning, you drive away with your local power plant."




http://www.madville.com/link.php?id=168737&t=9

[TreasonousBastard]

1. Stirling's been around for years, and I had one in the 70s...

that ran on solar. Or a candle when it was dark. Stirling seems to be great for smaller applications at constant speed. The external heat source could be advantageous if you've got a way to use unused heat.

Part of the problem is you're still burning stuff at low efficiency, evne though you're often burning waste.

[IChing]

2. He is running a car with it now

that is why I said it was a 'new' sterling engine.
This guy is the Thomas Edison of our times.

[TreasonousBastard]

12. Be interesting to know how he solved the lag problems...

with variable speed. Stirling as a generator in a hybrid system would be interesting, but as the primary power seems a bit odd.

[Blackhatjack]

3. What was the scale of the solar-stirling engine you had? Did you build it from a kit?

If you could condense solar imput, why wouldn't a stirling engine make sense as a totally emissions free source of power?

[IDemo]

4. They're way ahead of you on this one

http://www.sprol.com/?p=265

[TreasonousBastard]

6. Interesting-- 30% efficiency but they won't say...

what the setup costs. 30% is probably close to the max because of mechanical efficencies, but we don't know what the next big thing in photovoltaics will be.

Putting it into perspective-- it looks like a $15,000 investment per home from what they hope will be the cost, and that's in line with wind systems.

[Blackhatjack]

7. How did you arrive at $15k per home? Some people need minimal amounts of electricity...

... especially if they currently have no electricity at all today.

Some electricity, even if just a very small amount, could make all the difference.

[TreasonousBastard]

9. There's some industry standard out there that...

everyone uses. Something around 14kW per home. Obviously some use more and some use less, but that seems to be a national average of some sort.

And, we're not talking kilowatt-hours here, or total consumption, just pretty much peak use. You may have 200 amp service in your home, but you're rarely, if ever, pulling 200 amps. The point is to build a system that shouldn't have to pull from the grid when it's putting out max power, but not to waste money overbuilding.

[Gold Metal Flake]

10. The next big thing in PV is already here: CPV.

Concentrated photovoltaic. Using high-efficiency GaAs multijunction solar cells under concentrated solar energy anwhere from 400 to 800 suns. Efficiency is around 40%. Industrial PV suppliers like Australia's Solar Systems are replacing the Si cells in their concentrator systems with the Spectrolab cells and basically halving their cost per watt.

It will be interesting to see what a higher-efficience Sterling engine can do. Such a thing can be stimulated by a variety of heat sources, like solar, geothermal or the burning of something, and the engines can do a variety of work. Could be a pump for some sort of fluid used in geothermal heating/cooling of a building. Cool stuff.

[IDemo]

11. There could be an added cost benefit to solar stirling over photo-voltaic

They can be run on external fuel sources such as landfill gas at night time or on cloudy days. This was done with a test installation at the Pima Maricopa reservation in Arizona a few years ago.

I think for now they are targeting industrial parks rather than subdivisions, but it might be interesting to see how well a much smaller unit would work for a single house, possibly using a fresnel lens instead of a mirror array to concentrate solar radiation.

http://www.clean-air.org/sundish.htm

[TreasonousBastard]

8. Actually, I'm big on Stirling for some things, and...

there was some little gadget I bought from a Scientific American ad. It didn't do much but demonstrate that it worled. There was also the neat coffee can engine I built from plans. Again, it didn't produce much power, but was fun.

Besides the usual possibilities, I'm wondering how to use waste heat for these things-- putting one in front of the fireplace or in the chimney, under the hood of the car...

[alfredo]

5. I've seen huge solar dishes with stirling's at the focus.

[Mayberry Machiavelli]

13. Well I hope the usefuless to hype ratio is a lot better than with the Segway, and more

like with the insulin pump.

Although the Segway HAS been useful as the butt of a lot of visual jokes on Futurama and the like.

[Subdivisions]

20. Edison had hundreds of failed inventions. Yet, the lightbulb. n/t

[Blackhatjack]

14. If stirling engines work in principle, what is the big technological hurdle to harnessing them?

there is no doubt that solar is an excellent heat source.
the engine does not have to run under all conditions to be useful.
the environmental advantage would have to be significant compared to fossil fuels.
Why is there no widespread commercial exploitation of this device?

[IDemo]

15. Stirlings are deceptively simple

Trying to extract more power from a given displacement is not as easy as it might be in an internal combustion engine; add more valve lift, hotter spark, increased compression, etc.

There is an excellent book (somewhat dated) that will explain more about Stirling motors and the research and development process than you ever wanted to know: The Next Great Thing: The Sun, the Stirling Engine, and the Drive to Change the World.

[IChing]

16. Nice link

I think that the possibilities of really being off the grid are possible
with many of the technology systems that have been invented and are working but
are off the media radar because of corporate interests.

[Blackhatjack]

17. What about use in conjunction with "plug-in flywheel hybrid" LINK

http://www.greencarcongress.com/2005/02/ldquoextremerdq.html

I realize this is a Feb 2005 article, but the concept seems to be backed up by legitimate scientific measures.

"AFS Trinity Power Corporation has unveiled a flywheel-supported hybrid technology that the company anticipates will enable fuel economy in the 200–250 mpg range. The Extreme Hybrid drivetrain—under development for light duty and heavy duty vehicles—is a plug-in hybrid that gets most of its power from the grid. The flywheel system provides greater efficiency in energy capture and release from regenerative braking, thereby extending the operational range of the vehicle in all-electric mode.

The hybrid drivetrain system consists of five primary elements:

Advanced lithium batteries that are recharged at night with off-peak power from the power grid

An advanced flywheel for improved energy capture (up to 80%) and storage from regenerative braking

Advanced power-conversion and management electronics

A high efficiency steady-state Internal Combustion Engine

An electric powertrain

A flywheel is a rotating, kinetic store of energy. As energy is drawn from the system, the rotating components slow down, and as the system is charged, they speed up. Flywheel energy storage grows in proportion to the flywheel mass and the square of its rotational velocity. The trick for a vehicle flywheel system is optimizing size and weight, durability of materials, rotational speed, speed of energy capture and discharge, and cost."

MORE

[TreasonousBastard]

18. Dunno about this-- it seems too good to be true, and...

back in the 70s there was a Mercedes hydrogen powered bus that had a flywheel tied to the brakes to gain energy while braking and then assist in acceleration,.

The flywheel thing seems to have disappeared in a fog of mechanical losses and instabilities. Too often there's a whiff of perpetual motion behind flywheel schemes. Maybe this two-piece flywheel will work, but mass is mass...

[Blackhatjack]

19. Here is a WIKI entry that addresses the flywheel energy storage system...

http://peswiki.com/index.php/PowerPedia:Flywheels

"In addition to energy density, flywheel energy storage systems (FES) also offer several important advantages over chemical energy storage. The rate at which energy can be exchanged into or out of the battery is limited only by the motor--generator design. Therefore, it is possible to withdraw large amounts of energy in a far shorter time than with traditional chemical batteries. Indeed, research into exploiting this property of FES systems to get short, intense bursts of energy is ongoing with the most notable projects being a magnetic tank gun and a fusion ignition system. Of course it is also possible to quickly charge FES batteries making them desirable for application in electric cars where the charge time could be dropped from a matter of hours to a matter of minutes."

COMMENT: Isn't the real advantage offered by the hybrid automobiles the 'storage' of electrical power versus the use of internal combustion engine power?

If so, why would the 'flywheel energy storage system' not be seen as an extension of the hybrid electrical storage capacity? If you could storage the same amount of energy with fewer batteries that would reduce the overall weight of the vehicle and improve the mpg. Plus the ability to provide higher amounts of needed power on demand would allow the batteries a longer life and use for only lower level power demands.

[TreasonousBastard]

21. "Short interim bursts" is the key here...

and flywheels have their uses but I don't think they can hold enough energy to do much significant work. Im the Mercedes bus, the flywheel was used to add torque for acceleration, but then it slowed down enough to be useless to actually run the bus.

Besides, there are always losses, and what are the losses involved in accelerating the flywheel to where you can get that energy back out?

A flywheel's energy storage is directly related to its mass, so more storage means more weight and you can't really get around that. With batteries, new technologies are increasing storage density.

[Blackhatjack]

22. thanks for the explanation ...

[TreasonousBastard]

23. You're welcome, but I'm not an engineer, so...

I don't have all the answers, just doin' some garage experimenting.

Keep looking for the answers-- someone out there's got 'em.

[Blackhatjack]

24. Keep NC State School of Textiles on Your Radar Screen...

... they are doing research on materials for the US Govt related to aerospace and industrial applications. They are part of the Centennial Campus which is a research partnership public/private.

The materials they are working on could make cars stronger and lighter --both of which contribute indirectly to increased mpg.

[eppur_se_muova]

25. Note that's Stirling with an 'i', not Sterling with an 'e'...

remember that when you're Googling etc. For example, you'd never find http://www.stirlingenergy.com (WARNING: The "What is a Stirling Engine" link wedged my browser.) And of course there's wiki: http://en.wikipedia.org/wiki/Stirling_engine

[Ezlivin]

26. Rumors had the original Segway powered by a Stirling engine

Although they proved to be false 60 Minutes did a story about a Stirling powered Segway.