Germans trying to replace Alternator with Thermoelectric Generators or TEGs
 

The alternator may be a thing of the past:

Here's the link:
Up in Smoke

This is the article:

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.

I like this idea. If there was enough current it could even power a hybrid type motor to assist the engine! (which would then cool down due to less work being done and therefore reduce the power output......Dang!!) Anyway, i like where this is going.

ollie

if they could some how harness the heat energy fromt he radiator and exhause .. yeah you could easily power the car and possibly a hybrid motor.. so mush energy is wasted as heat energy in a ICE.

Yeah, BMW is working on this too. I assume they're using Peltier elements (Seebeck effect), as used by NASA on their spacecraft. Currently they're at 200 Watts, but need about 1000 W to be able to ditch the alternator, their guess is time to market 5+X years. It would yield a 5% reduction in fuel consumption.
They're also working on an exhaust-heat-driven expander (steam generator?) mecanically coupled to the crankshaft. It uses 80% of the exhaust heat and reduces fuel consumption by 15%.
Leave no stone unturned!

Bah, forget that TEG nonsense.

I've got one word for you: Organic Rankine Bottoming Cycle.

It's cogeneration for your car. Take your hot exhaust, run it through a boiler, boil a refrigerant (Florinol 50, usually), run that refrigerant through a turbine coupled to a generator, and get "free" energy from the waste heat.

All these ideas are great, but the capital cost will kill you (not unlike diesels or hybrids).

It's a great idea, I wonder what the premium would be on cars with TEGS?

Or there's this: http://www.carpages.co.uk/news/tigers-22-09-05.asp which is basically a turbocharger driving a generator.

The question, though, is why mess with band-aid solutions for the inherently inefficient IC engine. Build Stirling engines, coupled to hybrid electric drives for quick startup & acceleration.

This rocks! It got me thinking. If the exhaust is shedding energy to a refrigerant, it would be cooler afterwards. Would it then be possible to either collect the CO2 or change it into carbon particles (with a catalyst?) that could be collected? Or in the case of diesels, collect the soot particles? I'm thinking out loud here!

ollie

why not just use the coolant system as the heat exchanger .. just like a refrigerant cooled PC.. same for exhaust.. but yeah there is a ton of heat energy lost.. reclaim it and you can at least get more efficient.. the TEG is a great idea as its super low maintance.. no moving parts and pretty fail safe..

Oh God!! You are talking my kind of talk!!!
This is almost within the serious ecomodders scope, no? Now my brain is frying!!

ollie

Always a good thing.

ollie

http://www.bowmanpower.co.uk/iqs/sid...mpounding.html
quasiturbine.promci.qc.ca/QTPapiers/QTCromExhaustWP0612.doc
Have a look here. Sounds promising
ollie

Do you guys have any idea how weak TEG currents are? This is about as practical as replacing your car battery with a potato.

Have a look here:
http://radionics.rs-online.com/web/s...176+4294956707
around 650 euro for 1100 watts. How much is an alternator?
I agree the cost benefit ratio is slim but its progress. These things should get cheaper in time.

ollie

If it is basicly a turbo, then it's capturing energy from the exhaust pressure, heat is still wasted with a turbo.

Maybe still some net gain though... and I think within ecomodder scope like vtec-e says. Maybe a supercharger in reverse to drive an alternator?

You could do more than one of these. Turbos typically drop exhaust gases about 500 F. There is still more than enough heat left to do more work there.

That totally just put the Dexter's Lab episode with potato power in my head :D

I did some more looking around on peltiers. These guys:Using a peltier to generate electricity - HomeBuiltAirplanes.com
were playing with the same idea. Turns out peltiers are around 10% efficient. Not too good then.
Now, with the turbo alternator, i think a stumbling block is in getting a generator that goes as fast as a turbo. If we gear down from turbo speeds, we are losing efficiency. I'm trying to find out more about switched reluctance motors as they seem to be whats used. Apparently they are very cheap to make. Doesn't mean they'll be cheap to buy though...

ollie

Here's some progress on generating power from low temperature differentials using a "reverse refrigerator" running R134a:
http://www.chenahotsprings.com/index.php?id=90

A hybrid Stirling engine... that would be awesome.

Would still need some sort of fuel to generate the heat in order to keep a sufficient heat difference between the pistons... but i suppose diesel / lpg could be used.

IC engines still have the highest potential Carnot efficiency - big diesels are getting over 50% now, and still wasting enough heat for a bulky Stirling or the new refrigerant turbine.

What about inject water into the exhaust and then use the mixture of steam and exhaust gases to spin a turbine? For even better efficiency, the water can be preheated by running it through a heat exchanger from the coolant.

NiHaoMike: have you seen BMW's Turbosteamer - Wikipedia, the free encyclopedia ?

Except my idea does not require a condenser that would degrade aerodynamics.

Spud power
 

Hmm, potatoes, maybe there's potential here! Not just one potato though. I see a bank of potatoes, a Prius battery pack with the batteries replaced by potatoes.
Or lemons...