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New technology promising to cut CO2 and save gas

Alternative energy comes from unusual sources -- huge rivers, massive arrays of silicon panels, nuclear reactions, and massive spinning metal blades.   But German researchers are getting power from a source that might strike scientists from decades past as particularly peculiar -- they're making power from automobile exhaust gases.

In an era of ultra-expensive fuel and concerns about emissions fueling global warming, the automobile has come under increasing scrutiny with users looking for ways to extend gas mileage and cut emissions.  Fraunhofer-Gesellschaft, a leading German research organization, is developing materials and designs for a thermoelectric generator which will help to solve both problems.

In automobiles, two-thirds of the fuel used is emitted as waste heat. In total, 30 percent of the energy is lost in heat from the engine block and a further 30 to 35 percent is lost to exhaust fumes.  Many teams of researchers have began to look at how to recapture some of this heat and heat from similar industrial engines and transform it into electricity.  Such devices are known as
thermoelectric generators or TEGs for short.

The TEG generator takes a temperature gradient, driven by the difference between the waste heat and the ambient temperature and uses that gradient to produce electricity.  Greater temperature differences yield great results.  The
Fraunhofer Institute for Physical Measurement Techniques IPM has a number of thermoelectric materials under development that will harvest this heat in automobiles. 

Dr. Harald Böttner, head of the Thermoelectric Systems department states, "The temperatures in the exhaust pipe can reach 700 degrees Celsius or more.  The temperature difference between the exhaust pipe and a pipe carrying engine cooling fluid can thus be several hundred degrees Celsius."

The
thermoelectric converter the team is developing takes the gradient created by the exhaust gas and uses it to drive charge carriers through a semiconductor.  This creates a looped current flow similar to a battery.  The technology is relatively straightforward, but the real challenge is finding optimal thermoelectrics with high carrier mobility.  The research team is hoping that the device will make the alternator obsolete, providing power to the car's consumer electronics, onboard computers, and charging the battery.  Böttner states, "This would make it possible to cut gas consumption by between five and seven percent,"

Researchers point out that with 50 million cars on the road in Germany with an average on-road time of 200 hours a year per car, if only one kilowatt each was produced by the TEGs, this would amount to
ten terawatt hours per year. 

The researchers are hoping to begin to construct prototypes of their designs very soon.



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RE: Potato meet exhaust pipe...
By Ratinator on 6/6/2008 7:19:42 PM , Rating: 2
So if this were to go around the exhaust pipe and the amount of energy created is relative to the difference in temperature between its surroundings and the exhaust pipe, would this not effectively work better in colder climates?


By JonnyDough on 6/9/2008 8:02:46 AM , Rating: 2
I wonder too about the heat in cars. Why is it that we don't have rear-engine cars in the south where they don't need the engine heat rising back through the car,
and front engine cars in the north where they need to pull heat off the engine to warm the car? That way when you run the AC or the heat, you don't need as much.

Why can't some sort of sealed steam contraption be placed over the motor, like a sealed and pressurized radiator that is used to generate energy from the heat? It would apply the same concept used in cooling pipe heat sinks on computers. The liquid boils, rises to the top where it's cooled, and then drops back down to be boiled again. It's a pretty simple concept.

We already lug the water around in our cars and heat it. We already use air to cool the water. Now why not let naturally rising steam do some work to make electricity to power the car? If you ran sealed pipes up from the engine along the top of the car and then down the back and return it to the front, wouldn't that be an effective cooling loop? Just write "Caution, Hot" on the pipe.

If this sounds unsafe because of a crash, I'm sure engineers would come up with a safe way of doing it. At the VERY least they could do this on semi-trucks somehow. Those things burn a ton of fuel. If we took all the trucks off the road suddenly, gas prices would plummet. And yes, I'm aware they burn diesel. Diesel is just less refined gasoline!


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