Posting in Energy
Car exhaust could be used to generate electricity, which would reduce fuel consumption.
Researchers at Purdue University are working with General Motors to create thermoelectric generators (TEGs) to turn waste heat directly into electrical energy for cars. The idea is to use the heat from the car engine's exhaust to generate electricity.
The prototype - which is a small metal chip - will basically hook up to the exhaust system and tap into heat coming from the gases.
The technology used today can't hold up against the high temperatures inside catalytic converters.
But the material the researchers want to use is called skutterudite, which is a mix of minerals. Then other rare metals are added to it to make sure it's a poor conductor. That way, the current is generated when the material is hot on one side and cold on the other.
Ideally, it would reduce the amount of fuel used by five percent. It does this as it generates electricity to help power the car's electrical system and charge its battery.
The applications of the technology go beyond car exhaust. It could generate electricity in homes and power plants from waste streams. Waste byproducts could supply 19 percent of U.S. power, the heat sure gets lost easily. The promise is there, but the technical hurdles remain.
Nov 24, 2010
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this is a very informative piece, even I didnât knew about the engines exhaust can generate this electricity. http://www.national.co.uk/branch-57-Newcastle-(Millers-Road-NE6).aspx
Consider the noise reduction when rotating parts get replaced, pumps may be difficult but alternators will go. Putting lower devices with less power consumption will make the energy go even further. There is a precaution about heat, beside how hot you are, especially when using gases so vent and insulation are required around the exchange area.
@Cosserat, BHartmann only said the potential improvement was worth following. He didn't say it should be on every car ASAP. It does at least seem worth a little more research. bb_apptix, an exhaust-driven turbine is indeed more promising and something I'd love to see investigated. The problem with thin solid-state thermocouples is that any heat engine's efficiency is limited by an absolute limit. 1st year thermodynamics is a long way behind me now, but I do remember that it needs to lose its heat to a sink significantly cooler than its heat source. Hence the references to "poor conductor", "one side cooler than the other" and I'm assuming that 5% is the theoretical limit of its total production.
Hook a turbocharger up to an electrical generator. Also, cosserat is correct. Engineering is a balance between cost and efficiency, and a balance between cost and features, cost and reliability, etc. An engineer designs to meet a criterium; he also needs to meet a cost point. As effieciency/reliability/features get closer to their maximum, the cost skyrockets. In virtually every case, these extra costs cannot be recouped.
This TEG is solid-state, no moving parts from the description. It may not be economical due to the cost of materials & of manufacture, but not because it's "complicated". The fuel savings will be partly offset by the weight of the TEG in a vehicle but not in a fixed installation.
6.bhartmann...11/25/10 said: "Any recovery or efficiency is worth following." No! All engineering, without exception, is a balance between cost and efficiency. So your comment, being absolutist rather than balanced, is completely at odds with experience in the real world where realistic balances have to be struck all the time. Absolutism is one of the least endearing aspects of eco-extremism where the "great idea" takes precedence over the pragmatic optimum. Real engineers are only too well aware of the pitfalls of unattainable perfection. I was expressing a personal view that the cost of extracting 5% more power via the means proposed would work out to be higher than the cost of manufacturing a more efficient engine. I might be right or I might be wrong but what I was saying is capable of being tested in the marketplace. Bhartmanns absolutism is not.
I disagree with cosserat. Any recovery or efficiency is worth following. Many years ago a Steam Turbine engineer told me that a 1/2 percent improvement would be worth millions. No reason not to pursue all avenues of improvement.
Only a few weeks ago you had a similar report and the blog trail argued this one out. From an engineering point of view it is much better to concentrate on improving the efficiency of the engine itself rather than to trying to extract 5% extra energy using such a complicated mechanism which, whatever the theoretical possibilities, is likely to be inherently expensive to engineer.
I saw a unit that used thermocouples to power a radio by placing it on a gas burner also there is another gas powered device which I have seen that is used to power remote telecom transponders in places where solar power devices would not be of use due to covering of snow stopping sunlight. Maybe banks of thermocouples are the answer,plenty around in use all over but one drawback anybody useing them would not be able to get a patent on their device.....
I've wondered why they weren't doing this! They should also be able to use the heat from the cooling system to generate electricity. And converting that heat to electricity (or motion) would also reduce the amount of heat sent to the atmosphere.
Orest Symko a professor of Physics at Utah University has some similar work where he has developed a combination of heat chamber that takes expanding air and the resultant sound that is fed to a piezoelectric crystal to generate electricity. The original idea was to replace heat sinks in laptops with this device to extend the life of the battery. The other applications, such as wrapping the exhaust and catalytic converter or the backs of solar cells that are being fed through prism amplifiers, are also great possibilities. The only limit is our imagination.