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BMW taps solar power to improve efficiency

Written by Nelson Ireson

Thursday, 15 May 2008

As manufacturers seek ways to create more efficient cars without compromising power or driveability, eyes are increasingly turning to new technologies and fresh ways to apply old ideas. BMW is looking to electricity generated by exhaust gas heat and solar power to take the electrical load off the engine and thereby improve efficiency and reduce emissions.

In fact, BMW has found that by reusing the otherwise wasted heat energy from a car’s exhaust up to 1kW of electrical energy can be generated. By installing a device known as a thermoelectric generator, the new electrical energy can be then used to power auxiliary components, such as air-conditioners and electric power steering systems, which usually draw energy from the engine. The end result is a reduction in real-world fuel consumption by as much as 5%.

Honda's work on the Rankine Cycle, which uses exhaust gas to heat water, creating steam that spins a turbine to generate electricity, has found as much as 32kW can be generated by the method, though the weight penalty for the device reduces fuel efficiency benefits to about 3.8% at a 100 kilometre per hour cruising speed for a 2.0-litre direct-injection petrol four-cylinder.

BMW is also working on employing small solar panels on the roofs of some of its cars. Prototypes have achieved 200W output levels, enough to improve efficiency by about 1%. Expanding solar panel coverage to the entire roof surface could generate up to 1kW, the same output as the exhaust-powered thermoelectric generator, and could benefit efficiency by the same amount, around 5%.

Other future technologies BMW is working on include regenerative braking, stop-start operation, variable frontal aerodynamics, electric power steering and a satellite-aided traffic management system that helps improve efficiency by anticipating when acceleration or braking will be necessary, and smoothing out the transitions between the two, resulting in better fuel economy.

In Germany alone, BMW estimates that up to 12 billion litres of fuel are wasted annually in traffic jams and other road hindrances.

The individual technologies are part of the overarching EfficientDynamics campaign to create more environmentally-aware cars while maintaining the driving dynamics that have made BMW famous.

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Comments (1) Add Comment

roulette strategy man, November 12, 2008 | 15:25

Modern day energy systems rely on explosion rather than implosion, and this generates heat. This includes electricity harnessed from solar power. Energy systems need to be more efficient and work on implosion, so they stay cool. The non-profit energy research organization at http://www.universalsymbiosis.org (also http://www.genuinewinner.com ) is active in these areas which will help reverse effects of global warming. They develop more efficient solar cells too. I suggest everyone also read "Living Energies" by Callum Coats which explains the work of Victor Schauberger and the importance of trees to our planet. They also cover efficiency of implosion vs explosion energy systems. Don't rely on information from the authorities as their advisors don't fully understand the life cycles of the planet. We need to push the authorities to develop forest management and sustainability plans, and this will solve at least part of the problem. But as for solar power, this is partly a solution immediately available to us if we only push the governments to act more on it.

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