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Ask Dr. Livejournal

Okay, here's the setup:

You got your hybrid car. You can add batteries to your car (a known hack) and plug it in to your house current to increase its overall MPG. Why not add solar cells to it as well? It won't help significantly while you're driving, but it'll help charge the car while it's sitting, assuming it's parked somewhere light.

Next, you can use Peltier chips to move heat. There's been some work on using them in air conditioning systems for cars (we're in the early stages) and they're commercially available in some refrigeration applications. Why not make Peltier cooling standard in hybrids? After all, it's gotta be lighter (weightwise) than carrying around the compressor and freon-like chemicals. For that matter, there's nothing stopping you leaving the a/c on when you're parked in the summer, to keep the inside of your car from becoming an oven.

So, why isn't this around yet? I'm no supergenius, and I came up with this using my spare brain power. Thoughts?


( 6 comments — Leave a comment )
Jun. 3rd, 2007 09:54 am (UTC)
Why not add solar cells to it as well?

Or order to add enough to make a difference, wouldn't you also be adding to the weight of the car (and diminishing its air resistance), thus reducing the overall MPG?
Jun. 3rd, 2007 11:52 am (UTC)
I can relate to the physics - but I can't do the mathematics. I know that solar cells these days can be a lot lighter - see the new solar cell cloth, for example. Nevertheless, this is why I asked the question - I was hoping someone knew, or could tell me.
Jun. 3rd, 2007 09:16 pm (UTC)
Well let see, you could get about 4-5 good size solar cells for the area that would face up, maybe a couple more if you did the sides also. While it would go a long way to maintain the batteries, it would be a far cry from charging the car. Even given Peltier chips to cool the inside, the solar cells would be fighting a losing battle. The more sun you get, the more power you would have to run the chips, but Solar cells at best are only %15 efficient in turning the power of the sun into electric. Peltier chips are better, but not much, around 28% effective. (however, you could use them in reverse and get power from the heat in the car... but that is another story)

While all that is going on, your windsheild and care are pretty good at keeping the heat in. Also the sun is pretty damn spiffy about transferring its heat into things like plant, brains, and people's cars.

In order get get enough power from solar panels to do any good, you would have to add three to four times the amount of surface space to the vehicle.

But me with my limited brain power wants to know why every government building's roof is not covered with them, that and why not every street light? One on top of each street light would go a LONG way into producing a good amount of power, even if its to cut down on the power bill for our government.
Jun. 25th, 2007 03:03 pm (UTC)

I still want a hybrid for my next car (5½ years ago there weren't many options on the market yet, they were too expensive, and I figured they hadn't had time to work out all the bugs yet) but I really don't want to be associated with "them"... those smug and snobby hybrid owners like the ones lampooned on South Park, or who drive around with vanity plates like "MPG2NV" (I just saw that one last week).

Jun. 4th, 2007 05:26 am (UTC)
With some of the new solar cells that are being worked on now, things may look a little better. Several new kinds are much more efficient, and there's also new solar technology that works far better in partial light. panels that sit "inside" the surface (not interfering with the profile of the car) may indeed soon be efficient enough to be worth the cost of including.
Jun. 4th, 2007 01:37 pm (UTC)
I bet tevarin would enjoy discussing such possibilities with you, if you two ever make it onto each other's friends lists.
( 6 comments — Leave a comment )