BMW working on regenerative exhaust system... with NASA?
Baby steps. That's how BMW expects to improve the efficiency of its vehicles – not by revolutionizing the automobile or replacing the internal-combustion engine, but by improving it. The Bavarian automaker's Efficient Dynamics program includes a roster of fuel-saving technologies like regenerative braking and start-stop engine management, but the second generation of the initiative looks to the heavens for inspiration. Specifically, to the National Aeronautics and Space Administration.
NASA's satellites are powered by thermo-electric generators (TEDs) which derive electricity from the heat generated by radioactive materials. BMW has no intention of putting plutonium in your car, but is working with NASA to adapt the TEDs to hook up to the car's exhaust system and provide some 200 watts of what would otherwise be (and until now has been) wasted energy. Capturing the heat to power auxiliary systems like climate control, BMW says the system could improve fuel economy by 5%. Not a revolutionary figure, but more than the contribution of both regenerative braking and start-stop combined.
[Source: CAR]
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Reader Comments (Page 1 of 2)
cyclone 9:39AM (3/10/2009)
dont forget the flux capacitior fellas!
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Brett- BMW Advo 9:41AM (3/10/2009)
they've been talking about this for years now. only this time NASA is involved, must be official. Hey, another way to drive BMW prices up!
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BigMcLargeHuge 10:03AM (3/10/2009)
Sounds like it will have to be a complex system just to gain a little energy. I'm thinking a core unit similar to a radiator working in your tailpipe to capture the heat.
If people have issues with a urea filter on diesels, this is definitely not gonna fly.
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jim 9:53AM (3/10/2009)
When I first read about this, I had two thoughts. First, what a great idea. Second, that's going to be bleepin expensive to fix.
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Sean 5:48PM (3/10/2009)
Wouldn't a more efficient approach be to make the engines more efficient?
I hear they have a lot of wasted heat...
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Sean 5:50PM (3/10/2009)
What? Seriously, I've heard the most inefficient part about modern engines is the excess energy lost in the form of radiant heat.
BoxerFanatic 10:24AM (3/10/2009)
Whoopie! A Zepplin!!
A turbocharger impeller hooked up to a little generator, instead of a compressor.
Snore.
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huisj203 10:33AM (3/10/2009)
First off, it's a TEG (as in generator), and it is a material that converts waste heat (from the exhaust) into electricity (as in to downsize the alternator and reduce drag on the engine). There is little magic involved--no turbines and very few flux capacitors--but it is an idea that shows a lot of promise, especially for large engines which waste a lot of the fuel energy as exhaust heat.
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J 12:21PM (3/10/2009)
right. Zero moving parts so it is very reliable. It is basically an array of thermocouples. Not very efficient, but when the energy source is free is doesn't matter as much as a Watts per kg or watts per $.
Mobius_1 10:41AM (3/10/2009)
But why? Just buy whole engines from NASA! And see if anyone dares to do M3 vs others comparos. :P
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TORONTO 10:42AM (3/10/2009)
Don't the older, air cooled Porsches use the heat off the exhaust to heat the cabin ??
I'm sure it's not the same process... but using the exhaust heat has been done.
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TigerMil 11:02AM (3/10/2009)
and it didn't work very well....VW had the same system and it corroded/failed quickly. One solution was stainless steel heat exchangers...IIRC they were aftermarket items; I don't know if Porsche/VW ever implemented the SS exchangers in production.
Lastly, exhaust to cabin heat exchangers is indeed trivial...this is thermal to electric generation...and on a multimillion quantity/scale. NOT has been done. Yes, Pu TEGs exist but are multimillion dollar items for long term satellite power.
why not the LS2LS7? 11:42AM (3/10/2009)
All cars (except maybe hybrids) use the heat off the engine to warm the cabin. That's why it takes a while before the heater works in your car.
Liquid-cooled cars do it by running coolant through a radiator and pump that air into the passenger compartment.
montoym 9:22PM (3/10/2009)
Part of the reason the old VW heaters didn't work was due to the engine being int he back of the car. Trying to force that heat forward was tough and they didn't use fans to do it. That's why most of the time, you had to be going highway speeds to get any heat out of it.
But yes, as LS2LS7 said, all cars use the heat off the engine to heat the cabin. However, I'm not sure any use heat off the exhaust to heat the cabin these days. However, many do use the exhaust itself to add power to the car(turbocharged engines). So that does recover some of the lost energy.
mattskull16 6:53PM (3/10/2009)
I highly doubt about the following fact:
"BMW says the system could improve fuel economy by 5%. Not a revolutionary figure, but more than the contribution of both regenerative braking and start-stop combined."
Mazda says that it's i-start system will get up to 12% better fuel efficiency in the city. If you do 50/50 city highway driving, it's 6% already, WITHOUT the regenerative braking.
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TigerMil 10:59AM (3/10/2009)
Quite possible. Some Greeks did a paper using a 1300cc Starlet as the car:
http://ect2008.icmpe.cnrs.fr/Contributions/P2-18-Hatzikraniotis.pdf
They only got a few watts but showed it was possible. JPL is also working on some microelectronics.
The whole thing will most likely be an expensive downpipe or header system that incorporates the thermoelectricgenerator TEG components. And yes, it will be more expensive than a stock downpipe or header!
FYI, Army (USAMC) has an RFP out for a 50-200 watt TEG for Army vehicles...
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oldraven 11:01AM (3/10/2009)
Didn't VW debut the very same thing last month?
http://blog.vadaenergy.com/?tag=vw-thermoelectric
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TigerMil 11:06AM (3/10/2009)
Someone ought to tell VW about the broad agency announcement:
http://www.fbodaily.com/archive/2009/01-January/07-Jan-2009/FBO-01726669.htm
The VW device has a claimed 600 watts while running on the highway...that's about the same as an early Chevy 12v alternator!
oldraven 4:32PM (3/10/2009)
http://www.autoblog.com/tag/volkswagen+thermoelectric+generator/
Even better. Autoblog reported it already on Feb. 10th.
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gslippy 11:12AM (3/10/2009)
Super expensive for not a lot of savings - sort of like hybrids.
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