Wood fired electricity may soon be possible

And I'm talking a new way here, not the old stuff. Got this from another board I frequent. General Motors has come up with a way to produce electrical power from the vehicle's exhaust. The idea is to replace the alternator with a heat generator mounted on the vehicle's exhaust. We'll need more details, but if they are successful then this will be something we can use to generate house power. I know this isn't a new technology, what is new here is the ability to generate a considerable amount of power from a fairly small device, like 1000 watts instead of 20 watts.

A typical mid-sized sedan has anywhere from a 100 to a 140 amp alternator, meaning they will have to cough up 1000 to 1700 watts from one of these devices. These devices must also be small enough to be mounted to a vehicle. So, if we were to take 10 of these and wire them correctly, we should be able to see as much as 140 amps at 120V. As most houses today have 100 amp service, or 200 amp if they are heated with electricity, this means that a bunch of these heat based electrical generators could power a house. The only problem is, how to get the heat into the device. It's designed to be wrapped around an exhaust pipe, and draw the heat from exhaust. I'm thinking that the same effect could be had by setting up a wood stove to heat a heat transfer oil, which would then be pumped through a pipe that has these devices strapped to it. You'd likely need to daisy chain the pipes together so as to have the oil run through a short section, then go back into the stove to pick up more heat, then on to the next set. Size everything right, and you could likely power the whole house from a single log.

So, if you had ten of these devices, how would you go about getting them heated up to the same temps as a typical automotive exhaust? You'd need as much as 500 degrees inside the pipe.

I'll assume that we're talking about Stirling technology. It's interesting, but not very efficient. However- an internal combustion engine is not very efficient either and much of the energy in the fuel is just lost as heat in the engine and exhaust. Recapturing as much of that as possible has been on the minds of engineers for a long time.

Your numbers assume that all of the electricity of the vehicle would be supplied by this generator- not so. The alternator would still be in the system creating spark. The Stirling generator would, I guess, give a little extra juice for things like the AC and peripherals- or it could be directed to power for say a hybrid engine.

http://electronicserviceonline.com/html/woodstovegenerator.html (link provided by crazy-dan)

Actualy what telco is talking about are thermo elctric generators (T.E.G.) They do entirely replace the alternator, providing all the electricity the vehicle needs from waste exhaust heat. If enough extra TEGs were installed (there is plenty of waste heat from any internal combustion engine, 70-80% of the fuel burned is wasted as heat), then some excess power is used to crack hydrogen from water, thus boosting gas mileage. Present day TEGs are about 4% efficient, but a new desin from MIT promises 20% recovery. By the way, modern sterling engines aproach 50% efficiency, and are being used in hybrid electric cars built in Norway and designed by Dean Kamen of New Hampshire.

Dunebilly's got it right. Stirling is the old hat, TEG is the new juice. If they think they have it close to being robust enough to put into an automobile and sell it to the public, then it would be robust enough to provide electrical power for a house. It would just be a matter of working out a way to reliably provide the correct level of heat into the device. Then you'd need some method to convert to power usable by the house, but 12V DC to 120V AC conversion gear is easily obtainable from a solar power equipment provider.