Creating Electricity With Exhaust Gas
by Michael Graham Richard, Gatineau, Canada on 09.24.05
A British group named Foresight Vehicle Visteon UK Ltd has created a device called TIGERS (Turbo-generator Integrated Gas Energy Recovery System). It uses the exhaust gas from a car's combustion engine to produce electricity, enough to power the vehicle's electrical system, thus taking a load off the engine; "Parasitic losses from mechanical support systems (i.e., belt-driven) can normally be as high as 6kW or 8hp in a family sedan but can be significantly higher in larger capacity cars and trucks. Moving from those mechanical systems to electrical removes those loses, and fuel consumption could be reduced from between 5%–10%." This technology could be coupled with hybrid technology and the extra electricity could help recharge the hybrid's batteries. "Because the system is fairly simple and partly based on existing technology, it could be fully developed for all car, van, bus and truck engines within a few years." Now lets wait for a successful mainstream implementation. Much more details available at the two links below.
Update: Thank you Chris Stevenson for correcting some errors in this post.
::Foresight Vehicle, via ::Green Car Congress
To my knowledge, all car exhaust systems are designed to achieve a specific "pressure drop" between engine exhaust ports and tailpipe. If you change the drop by creating a backpressure with a device like this, engine performance and part life could be impacted. Not sure what the result is but I would not put one on unless I knew first for certain that valves would not burn, oil get dirtier, and engine temp elevated, for example.
John, the point was mentioned on GCC. It seems that a car with that device would have an exhaust designed to compensate for that. The might be some losses, but they would be more than compensated by the gains..
This looks like a sound design, as the device its self uses a bypass and a valve to limit the gas flow through the turbine. This means that high engine loads, performance need not be affected very much, which is good for engine perfomance and good for managing the output of the generator. Also, exhaust system valve technology has been in use for well over a decade in motorcycle engines, so is not really an issue.
I've always wondered why turbines aren't inserted in the cooling system to make use of the tremendous waste heat generated by an internal combustion engine. My only thought is that the added weight of such a system would more than cancel out the energy that could be scavenged, otherwise I assume we would at least see such a system in prototype form, even if it's not cost effective.
Hm, I wonder how the efficiency gains compare to simply adding a turbocharger?
You can get more power out of the exhaust then you loose to backpressure. Turbo's can be designed to actually improve fuel economy. If you added batteries and drove ALL of the accessories like water pump ac and power steering with electricity generated by this device you would have a good mpg gain. Kinda like a half hybrid. Even better you can now stop the engine during cruising/stop lights etc with just a little more work.
It'd be interesting to see what kind of effect combining this technology with that of the hybrid tech used in cars like Toyota's Prius would have.
I saw one of those "Rides" shows last week where, due to space constraints, the rebuilders stashed a turbocharger back near the fuel tank which made me wonder how having the turbo in a much cooler area affects things...
Its fascinating to see the advances that are starting to come about due to the ever-increasing economic pressures. Sure, these may be stop-gap measures in the big-picture of things, but it is encouraging nonetheless.
Rob
Foresight Vehicle is a "knowledge transfer network", and is the company that put together the TIGERS project. The participants are Visteon UK Ltd, Switched Reluctance Drives Ltd and the University of Sheffield.
You can learn more here:
http://www.foresightvehicle.org.uk/dispproj1.asp?wg_id=1145
http://www.foresightvehicle.org.uk/proj_papers_pubs.asp?wg_id=1145