From: muller@Alliant.COM (Jim Muller)
Subject: Where does the energy go?
Date: 16 Nov 89 16:50:44 GMT
Reply-To: muller@alliant.Alliant.COM (Jim Muller)
Organization: Alliant Computer Systems, Littleton, MA
Lines: 101

I recently read Pat Bedard's column in the December issue of Car&Driver. I am compelled to write because his column touched on something I have almost written about before, but (once again) his assheadedness made his words less weighty than they might have been. One issue he brought up was global heating. (It is not the main point of this posting, but it is significant enough to warrant a few words.) First of all, he made jest of the entire subject. Well, perhaps we aren't about to melt the icecaps in the next 10 years, but it *isn't* a problem to ignore until it goes away either. One way to think about it is to examine what the consequences might be if you guess wrong on either side of the issue. There are four combinations of results. Either it is or isn't a problem, and either you do or you don't do something about it. (We will assume for the moment that you *can* do the right thing if you decide to do anything at all.) Should you guess right, either to or not to do anything, then all is well: you live your life as before if it means doing nothing; or you pay the price of the fix, but at least nothing dreadful happens. The interesting questions are what happens if you guess wrong. If you decide to fix it but you needn't have, all it costs you is the price of the fix (which may be substantial, but at least nothing dreadful happens). If you decide *not* to fix it but you *should* have, then dreadful things *do* happen. So the last choice is one to be avoided if at all possible. In this light, the other wrong choice becomes one of cheap insurance. What if you're wrong? What if you're right?

All this is a simplification, of course. The cost of the fix may be high indeed, and just knowing what the proper fix is may be difficult, not to mention actually managing to do it. It is a serious problem that should not be ignored. Mr. Bedard suggested that Pittsburg having Palm Springs weather might not be such a bad thing, but that if global warming did happen, his property values in the sun belt would drop out of sight. Those attitudes are quite narrow-minded (and selfish too). And they were not offered totally in jest, since the entire thrust of his column seemed to be that the idea of global warming was ludicrous.

Enough of that. Here's my real reason for writing. Mr. Bedard said the way to avoid creating heat was to avoid hitting the brakes. Well, of course. In fact, this is a very significant and non-flippant statement, so it's too bad Mr. Bedard made it so flippantly. He suggested that all this heat contributed to global warming. In fact, this heat contribution is insignificant in itself, while the effect of IR absorption from all the CO2 driving produces is the real killer. That premise is on the mark, sort of, but for the wrong reason. He is right about hitting the brakes though. In fact, you'd like to improve your gas mileage for both economic and environmental reasons, and one way to do it is exactly as he suggested: Drive so as never to have to hit the brakes (unless or until absolutely necessary). You will burn less fuel that way, since it does indeed convert kinetic energy to heat. To describe this in simple, nonmathematical terms is messy, but actually driving this way is not so hard to do in practice. It would help if we knew more about traffic in the unknown immediate distance ahead, or about the intentions of other drivers on a time scale of a few seconds. We can't know these things, but we can still improve. We can drive as smoothly as possible. We needn't follow as closely as we do. We can drive as *predictably* as possible so *other* drivers will hit their brakes less. We can do all this and still get to where we are going safely and in a reasonable amount of time and in a spirited (non-boring) manner. It just takes a little more thought from minute to minute.

This concept of energy-lost-from-braking is so subtle but powerful that we are prompted to ask the following: When you burn N gallons of gasoline on any given trip, how much energy actually goes into heat (as opposed to some other energy form), and how much of the potential carbon-fuel gets converted into that vile fiend, CO2? The answer is *all* of it!! Well, maybe the chemistry is a bit funky, but (chemical energy in the byproducts aside) the energy balance is not. If you burn N gallons, you have burned N gallons, and it doesn't matter if you did it in 10 miles at 65 mph with a 4-cylinder or in 5 miles at at 52 mph with an 8-cylinder. The 4-cylinder may give you more bang (i.e. miles) for the buck, but the cost is the same. *All* of the energy burned is heat produced and you recover *none* of it. And *all* the fuel is CO2 produced if the combustion is reasonably complete.

Is this an obvious fact (and am I being flippant)? No, to both counts. The heating-by-braking part is obvious, but the wind and sound parts are not if you haven't thought about it. To force a 65 mph bubble of turbulence through normally calm air until you have burned 10 gallons of gasoline is exactly the same, heat/energy-wise, as driving at 35 mph and hitting your brakes every 1/4 mile until you have burned 10 gallons. If you let the 65 mph car coast to a stop without using the brakes, it would still produce the same amount of heat as braking to a stop, except that you'd go a little bit further down road, taking progessively more time to finally come to a stop.

So the way to use less gas, save money, produce less heat, and produce less CO2, is to drive so as to produce less heat of all sorts, i.e. driving less, and driving more efficiently braking-wise and wind-wise. For some people, mileage requirements are fixed by social or job requirements, so they have little choice about the distances they drive. Most of us do have some choice though. We just choose to ignore the costs. If we drive so as never to hit the brakes unless or until necessary (which means driving smoothly and letting other people around us drive smoothly too), and so as to produce as little turbulence as possible (which means as slowly as we can tolerate and for no more distance than necessary), then we are being efficient. The economic and environmental impact we save on trips we *have* to take is money in the bank we can spend on more trips of a more recreational nature. I prefer as much recretional driving as I can get. So, okay folks, lighten up on your routine stuff and save it for the Quality Time.

The other apparant intent of Mr. Bedard's column was to make fun of efforts by some people to protect our environment, whether the efforts are misguided or not. Of course some are misguided. (I don't agree with them all either.) Better that *someone* care enough, though. The alternative is that we all go to hell in Mr. Bedard's handbasket with our eyes closed.