But here's where the lesson comes in: that heat from the tailpipe, the heat that was burning ol' Joe's hand, doesnt go away. Oh, sure, ten feet from the car you wont feel it, but that's because it dissipated.Heat, like any energy, doesnt just go away, it instead spreads itself out as part of Energy's relentless attempt to equalize itself out over the entire span of Creation (this process, fortunately, takes a really, really long time, and is otherwise known as entropy).
On a more local scale, one little car engine doesnt add much heat to your environment. There is a lot of matter for the heat to spread itself out to. But there's more than just one car, isnt there? There are millions of them. Each one of them is burning fuel, and not very efficiently, I might add. The average automobile engine is only about 20% efficient, in other words, only 20% of the energy potential of the fuel goes into making the car go, the rest is just waste heat. (dont feel too bad, those bulbs you light your house with are only about 5% efficient). Heat that is then dissipated into the world around you. Over time, this has to have a warming effect.
How about another demonstration, this one less cruel. Get into your car, drive out into the countryside, far from the things of, if not Man, then City. Ahhh, that's better, isnt it? It's cooler out in the country. That's partly because you're no longer surrounded by cars, trucks, signs, and electronic devices, all generating heat (feel your TV, or your phone charger) as they go about their business, heat which spreads out and disperses into the things around it.
But there's something else going on out in the countryside, also. Sunlight, rather than falling on the concrete, brick, metal and asphalt of the city (where it is stored, and then radiated back out later on), falls on plants (assuming you're not in a desert). Plants use this energy (heat) from the sun to convert matter into more plant. Dont ask me how much energy they absorb, it's probably not a very large amount, though. But, again, like your car in reverse, there are a lot of plants.
Okay, now lets get back to your car. What does it burn? Unless you're a really Green type, it probably burns a petroleum product, like gasoline. Where does gasoline come from? It's made from crude oil. And what is crude oil? It is the decomposed and compressed remains of millions, billions of years of plant matter. You are in effect, using solar energy, collected over eons by the patient harvesting of plantlife. Unfortunately, as I said before, we only use about 20% of the trapped energy to get about. The rest is heat, solar heat (sort of), released back onto your town, almost all within the last 100 years or so. Every car does this. Every tractor-trailer rig. Every diesel locomotive, lawn mower, leaf-blower, motorcycle, motorboat and jetski.
Think about that, next time you're sitting in your car, engine idling to keep the A/C running.
Then multiply it by millions of times.
6 comments:
What if you don't have a/c in your car?
I suppose that depends on where you live. To not have A/C in Texas, for instance, is crazy. A/C on or A/C off, the important factor is the gasoline burning in the engine. For years I drove without A/C, but that was less about the environment than it was about me being a cheap bastard.
The whole post was spurred while waiting for my daughter to get out of school. I was sitting under a tree while I waited. 10 feet away, in the street, sat a car, idling with the windows up. Every once in a while, an errant breeze would blow a gust of heat from the car over to me. The post was more about the creation of man-made heat than about A/C (which really just moves heat around, rather than creating much of it).
With gas around 3 bucks a gallon, you'd think everybody would shut off the car, and get out into the shade, but apparently not. The small truck I currently drive has A/C, and you better believe I use it. Most of the time. In the summer.
We live in the country, in a house surrounded by trees to keep our use of energy down. Used the a/c this year because I'm too freakin' pregnant to go without it, but we never turn it down too much. I only use the A/C in cars when absoluitely necessary, though I was under the impression that it ran off the battery.
Nope, A/C runs off the engine, from a belt. The battery is mostly for starting, after that the cars electrics (including the blower on the A/C) run off the alternator, which is run by the engine. The engine has a switch which automatically kicks the idle speed up a notch when the A/C comes on (it does not run constantly, except when set to high). Higher load on the engine means more gas used.
You're lucky to have trees around your house (my rental does not, one of the few in the neighborhood, and suffers for it). You're also lucky to live in Pennsylvania, where no matter how hot it gets, next week will be cooler.
Here in Dallas it has been in the 90's nearly everyday since mid-May, in the upper 90's since mid-June. It's been over 100 degrees for 34 days so far this summer, the last ten having been consecutive. This is projected to go on thru the weekend. It will not actually be fall-like until mid-November. This is why I use the A/C.
Its 100 at least every day..and the humidity goes to wring out your pants to dry as a desert..its the lovely San Joaquin valley..
I do have A/C in my current car..but dude..I drove for years with out..even in AZ..I shat you not.
Yeah, so did I, but I'm getting old and fat, and cant take that shit any more. Gimme cold air when it gets over ninety, please.
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