Waste Heat to Electricity

Lots of interest lately in capturing the energy in exhaust heat from internal combustion engines. Converting that energy to useful work makes a lot of sense - if it can be done cost effectively.

Last week I sat in on a presentation by John Fairbanks of the U.S. Department of Energy about thermoelectric applications in vehicles. He estimates a there's enough waste heat generated by a Chevy Suburban (and space under the chassis for the system to fit) to produce up to 800 W of power. Efficiently capturing such energy would enable the vehicle to power accessory loads such as the cooling fans, navigation and entertainment systems, and so forth. This is intended to help enable the "beltless" vehicle in which the engines don't have the parasitic loads they're currently saddled with.

Air conditioning is a big load so there are also proposals to eliminate R134 (a big source of greenhouse gas emissions) and shift to "zone air conditioning", which would blow cool air from individual seating positions. This would only require a fraction of the power needed to cool the entire cabin. So perhaps a thermoelectric generator would have enough power to handle it.

GM, BMW and Rolls-Royce (owned by BMW) are all currently developing such systems and are targeting the year 2012 for production. Something else interesting was said. If the efficiency of such systems reach more than about 35% efficiency, the IC engine could be replaced by an external combustion engine that burned anything, since that would be a more efficient method.