BMW aims to put rocket science in your car
GENEVA (Reuters) - Germany's BMW wants to use NASA technology to
boost the fuel efficiency of its luxury cars and lower emissions of
harmful greenhouse gases.
Engineers at the BMW's high tech experimental lab in Palo Alto,
California are attempting to adapt the thermoelectric system for cars
that NASA scientists employ to help power their deep space probes
navigating the far reaches of the solar system, BMW's director of
vehicle integration told Reuters.
The NASA probes use so-called radioisotope thermoelectric generators
(RTGs) which transform heat emitted from naturally decaying plutonium
into electricity. BMW wants to bring this concept back to earth by
reclaiming the thermal energy released in engine combustion.
"I firmly believe that when you look at this technology in 20 years,
this will be the key issue that will replace everything else," Hans
Rathgeber told Reuters in Geneva.
Rathgeber said simple physics prevents a conventional combustion
engine from ever exceeding one-third efficiency. A motor with an output
of 200 kilowatts (kw) generally creates 400 kw thermal energy as a
waste by-product.
Recycling this abundant energy source would require replacing the
plutonium in a RTG with a non-hazardous material that conducts
electricity while resisting heat, not an easy task since most metals
become hot when a current is applied to them.
BMW settled on a semiconductor element called Bismuth Telluride as a
link between the car's engine coolant and its exhaust gas manifold to
fuel the thermoelectric cycle.
Simply put, a charge is induced when you heat and cool two separate
ends of a closed circuit. The amount of electricity generated is
proportionate to the difference in temperature at the two points -- a
property known as the "Seebeck Effect."
According to BMW's Rathgeber, batteries are better suited to storing this energy since it is constant and predictable.
Hybrids like the Toyota Prius by comparison have difficulty
transforming quickly and effectively the rapid changes in a moving
car's kinetic energy that is harnessed as electricity when the momentum
slows or comes to a stop.
FIVE YEARS TO MARKET
"When you have brake energy recovery (as with hybrids), you produce
and trap electricity in a battery every time you take your foot off the
pedal. With the thermoelectric generator, electricity is produced every
time you step on the gas so it's an ideal supplement," he said.
A full-size BMW sedan like the 530i could reduce its fuel
consumption by as much as 13 percent, or 1 liter less petrol per 100
km, simply by equipping it with a thermoelectric generator.
Not only would drivers save at the pump, BMW can lower the carbon
footprint of its luxury cars just when automakers are forced to cut
overall European average fleet emissions to 120 grams of CO2 per
kilometerstarting 2012 or face heavy fines.
BMW's cars in Europe still spew out some 156 g/km of CO2 across its entire model range, for example.
Since thermoelectric generators are too expensive for the automotive
applications, BMW says it needs to bring the extra cost to the consumer
down below 500 euros to successfully commercialize the technology.
"We are working intensively on it and in round about five years I think we will have this in series production," he said.
Since the technology has far greater applications than just the
automotive industry, trend scout BASF Future Business GmbH is in talks
with BMW over a cooperation to research improved semi conducting
materials with thermoelectric effects.
According to researchers, more than 60 percent of the energy
produced in the United States is never utilized, most of it melts away
in the form of waste heat.
"We have thermal energy loss everywhere, so it's a very interesting topic for the chemical industry," Rathgeber said. [ http://www.reuters.com/article/lifestyleMolt/idUSTRE5282Y320090309?pageNumber=1&virtualBrandChannel=0 - Reuters ]
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