On the back of your car, put some little solar panels. At night, the headlights of the car behind you will charge your battery, helping light your lights. (DC power the whole way.)
In traffic, car A feeds car B feeds car C feeds car D. Don't be the one to break the chain! Or, pestilence will fall upon you.
*Added bonus: If you ever find someone parked with their lights on, you can park backed into them, harvesting their folly!-- sophocles, Mar 21 2006 Solar Cell Stuff http://www.solarexpert.com/pvbasics2.htmlIntroductory-level info on solar cells [neutrinos_shadow, Mar 22 2006] Leave it to Ford to bake this idiocracy! http://www.autoblog...x-get-big-reaction/unbelievable [sophocles, Apr 21 2006] Drive your car at night in front of ten people you know and you will receive one milliwatt of energy.-- normzone, Mar 21 2006 Cool, finally a way to make use of annoying tailgaters.-- phundug, Mar 21 2006 One milliwatt? Is that accurate?
Regardless, it also charges during the day, more than doubling efficiency.
Wait a minute. My house has no garage, which mean I keep forgetting other people put their cars in dark boxes...-- Darkelfan, Mar 21 2006 When I was young a friend of mine had spot lights in his trunk. If the car behind annoyed him in anyway he would press the trunk opener and turn on the spot lights. They usually backed off quickly. He would then turn off the lights and accelerate quickly causing the trunk to close.-- Braindead, Mar 21 2006 silly [normzone], a milliwatt is a unit of power, not energy.-- sophocles, Mar 21 2006 [Darkelfan] Good idea! You'd just have to park on hills, facing the car's butt into the sun, and hope that nobody parks close enough to cast a shadow.-- sophocles, Mar 21 2006 [sophocles], I had my sarcasm key toggled off, it was intended to resemble the text of a chain letter.-- normzone, Mar 21 2006 Does anyone know someone who knows the efficiency of a square meter of solar panel, and the power input and radiant output of headlights?
Nice, [norm] if you look at it right, the idea is a chain letter.-- Darkelfan, Mar 22 2006 From a quick google, the best PV cell efficiency is less than 24%. The best cells are the ones used on sattelites; I think they are gallium based rather than silicon (someone correct me if I'm wrong).-- neutrinos_shadow, Mar 22 2006 Not to sour the flippant side, but: 30% capture of headlight output, light bulbs are 50% efficient, and solar cells are 20% efficient, you'd only power about .2*.5*.3 = 3% of the tailgaters headlight energy used to power YOUR headlights.-- sophocles, Mar 22 2006 30% sounds too optimistic to me for capture.-- RayfordSteele, Mar 22 2006 I think 3% may pay for the solar cells, over the lifetime of the car. Just my estimate, though.-- Darkelfan, Mar 22 2006 [RayfordSteele], if you want to capture more, just slam on the brakes a lot so people's headlights get closer, duh.
100W bulb, 3% recovery.... let's say a generous 3 hours/day, ~300 days / year, 10 years life of the car.
100*.03*3*300*10=27000 Wh = 27kwh
In the US, ~$.10/kwh, so... WE'LL GET AN AMAZING SAVINGS OF TWO HUNDRED AND SEVENTY cents over the life of the car.
Invest now!!!-- sophocles, Mar 22 2006 It wouldn't be able to help your headlights much, but might be able to power an LED. Or perhaps an array of LEDs. In your back window. Spelling out a message...-- lurch, Mar 22 2006 It's impossible. Calculations aside, collecting a given amount of energy from a car's lights and putting exactly that much energy into the car in front of you is impossible, unless you propose a 100% efficient solar panel (and electrical wires with 0 resistance). Also, lights don't have the same effect on solar panels that the sun does. I'm not quite sure why, but someone here could tell you, surely.-- jellydoughnut, Mar 22 2006 [jd] its just a question of insolation. In round figures the sun provides 1kw per square meter (earth surface-sea level-clear day-noon-equator) If you have a big mother of a light close enough to your panel to match that then the solar panel will have the same output as if it was hit by natural sunlight. So it will still convert at between 15 and 23% efficiency depending on your set up. Following headlights would not provide anywhere near as much insolation as this, so everybody who bunned this please hand back your high school diplomas:)-- ConsulFlaminicus, Mar 22 2006 Regarding headlights versus sun. As I understand it, the sun is slamming out lots of ultraviolet light, which has more power per photon, and kicks electron butt in a solar cell. Car headlight filaments don't put out much UV, and are covered with glass, which blocks UV. For solar power, the amount of light and its spectrum must both be considered. That hulking SUV behind you hasn't really got much power in its headlights--just enough to blind you.-- baconbrain, Mar 23 2006 [baconbrain], good point, but even if loss of UV spectrum reduced the efficiency by 50%, you'd still save about ONE HUNDRED AND THIRTY FIVE cents worth of energy over the life of the car.
About 3 car's worth, and you could buy that pocket calculator you always wanted....-- sophocles, Mar 24 2006 I posted this as a "physically possible", but "economically foolish" idea, and, sure enough, Ford Motor Company picked it up and implemented it. (see link). FOOOOOOLS!
US automakers just don't get it!!!! The next car I buy will be my 2nd Toyota Prius!-- sophocles, Apr 21 2006 random, halfbakery