BMW Unveils Efficiency Innovations
You know BMW is serious about improving efficiency when you hear they're equipping the M5 with a stop-start system. But what else have the bayerische wissenschaftlers been cooking up to improve efficiency? Auto Motor und Sport brings us up-to-date on the innovations unveiled by BMW at its unimaginatively named "Innovation Day 2008." One concept that's sure to have green chins wagging: solar roof panels designed to run the cars' electrical systems. BMW estimates a square meter of roofspace in northern European conditions could deliver 200 watts; more still if the entire roof's covered in photovoltaic cells. Solar panel could be used to reduce dependence on efficiency-sapping alternators for on-board systems, which could deliver small improvements to efficiency (0.3 fewer liters per 100km driven) or pre-heat the engine and fluids, improving inefficient cold start fuel consumption. Bimmer's boffins are also looking at generating electricity from excess engine heat. BMW claims that current thermodynamic generators from aerospace applications could deliver 200 watts of electricity today, with up to 1k watts available next Thursday (or so). The combination of thermodynamic generators, solar panels and engine pre-heating could yield a five percent increase in efficiency. We'll wait until we see a cost – benefit analysis, but the propeller people deserve credit where CAFE credit's due.
Mandatory car covering at work - the energy recovered by the solar panels could help pay off the cost. There are mouse pads that conduct electricity to power the wireless mouse on top (without electrocuting the user, of course). I'd like to see that applied to an EV vehicle.. park your car on a garage mat - no plugging in needed. Your car could be charged at work automatically, the funds deducted from your check, and visiting a gas station would be a thing of the past ;-) of course, getting the batteries up to par might be a first step......
In addition to the solar cells, the car could have a series-parallel switchable 12V/24V battery stack and a thermopile integrated into the catalytic converter and cooling system to charge the batteries. This would eliminate the alternator, and allow the use of a smaller starter motor (24V). Short-term increases in electrical demand (which used to be covered by the alternator/voltage regulator) would be managed by switching the extra battery capacity into the 12V loop. One also has to rely on a level of inefficiency of combustion to keep the converter hot enough to supply power, possibly by increasing the fuel/air ratio to maintain cat temperature. You could easily gain 5% efficiency with such a system. Or, just make it a hybrid drivetrain for the same expense, and get a 30% gain.
Solar panels are getting lighter, cheaper and more powerful every year. Batteries are getting lighter, cheaper and more powerful every year. Given the ability to convert sunshine and braking energy into useful electric energy to power an electric motor at low speeds it just seems so obvious that there's a very efficient hybrid system that could be applied to virtually all new cars in the next decade.
maybe we should all just drive smaller cars. way easier. gas tax.