atomic_fungus (atomic_fungus) wrote,

#1071: No, it fails.

Various people on Jerry Pournelle's mail page discuss the relative benefits and liabilities of ethanol and flexible fuel vehicles.

One person opines that even taking a 33% hit in fuel economy, a vehicle using a high-ethanol blend ends up using only 0.2 gallons of gasoline versus one gallon of E85 (which is a fuel blend of 85% ethanol, 15% gasoline).

What this does not consider, however, is the gallon of diesel fuel required to manufacture that gallon of E85. (Okay, the 0.85 gallon of diesel required to manufacture that 0.85 gallon of ethanol which makes up 85% of the gallon of E85.)

Put it all together and you've burned 0.85+0.85+0.15=1.85 gallons of fuel to save 0.85 gallons of gasoline. If carbon dioxide is your favorite bugaboo, you've ended up making things a lot worse than if you'd just used the gallon of straight gasoline. And in the process you've cut the fuel economy of your car by about 30%, so to go the same distance you've actually got to burn more fuel--and so in actuality the "1.85" figure is probably closer to "2.15".

Whereas the guy who's burning straight gasoline is gallon.

(I'm not including fuel used for shipping in this. It's the same for both straight gas and E85 and we can safely ignore it.)

At the pump, E85 is $0.50 cheaper than straight gasoline. For your trouble, you get about 70% of the fuel economy. With gas at $4 per gallon, it's a bad tradeoff, assuming your car gets 30 MPG, because the extra 30% of a gallon you need costs $1.20: you pay $5.20 to go the same distance on E85 that you can go on a $4 gallon of regular. In fact, if gas is $3 per gallon, it costs you $3.90 to go the same distance on a gallon of the unadulterated stuff.

The $0.50-per-gallon price break doesn't pay for itself unless fuel is under $2 per gallon, in fact: at $1.67 per gallon, 0.3 gallons of E85 costs $0.501, and the decreased fuel economy does not make a cost difference.

I think I need not emphasize that gasoline is currently more than twice that price. Even in places other than Chicago. Even E85, which is only cheaper because of government subsidies.

...and so I now must set aside the balance of this entry to make fun of Spider Robinson.

In his novel Telempath Spider Robinson asserted--in several places--that alcohol was superior to gasoline in every respect, including its chemical energy content.

This is why I can't take him seriously as an SF writer. Every book of his that I ever read had something in it which made me go, "Huh? That's crap!" But none were as bad as this nonsense from Telempath.

In one of the Callahans/Lady Callahans books, he had someone (who was coated with some kind of hypertech body armor) get shot in the mouth, and the bullet ricocheted around in her head for quite some time before it stopped. I think he was overestimating the amount of kinetic energy a bullet can retain even when blasting through the relatively soft tissues of the human head. (He also made the point that a handgun isn't accurate beyond point-blank range. The first time I fired a handgun I was able to hit a target 50+ feet downrange. The first time.)

The thing that made me stop reading Robinson was when he included Bertie Wooster and his "man", Jeeves, in one of his Lady Callahan books. He characterized Wooster as a gay bondage freak. The scene was adolescent and juvenile and reminded me of something you'd see in a junior high student's notebook: "ha ha, I can make these guys be gay and into BDSM! I'm clever and this is funny!" As a fan of Wodehouse, it just pissed me off. Bertie Wooster wasn't gay; he avoided marriage because the women he would have been marrying were all scary, domineering harridans.

But the alcohol thing, that wasn't a matter of opinion, and I knew it was wrong.

Robinson's mistake came, I think, from the fact that certain types of race cars use alcohol for fuel. That is true; but it's not because alcohol is inherently more powerful. Quite the opposite, in fact: it has a much higher "octane rating" than gasoline does, and so it's good for use in vehicles with very high compression ratios and forced induction systems.

When you're running a turbocharger or a supercharger on a high-compression engine (anything above, oh, maybe 9:1 or so) the last thing you want is predetonation. A good backfire can destroy your turbo, and once the backfire is over the engine will suck bits of destroyed turbo into itself, thus shredding the engine too.

Drag racers actually have to have straps on their superchargers to keep them from becoming airborne in the event of an explosion.

And race cars with forced induction run insane amounts of boost--30 PSI is not uncommon, which is twice the ambient atmospheric pressure, and drag racers run perilously close to hydraulically locking their engines with the fuel/air mix they use.

The other advantage of alcohol is that it mixes with water. If there's a fire, you can hose everything down with plain old H2O and put the fire out. Not so with gasoline; set a pool of gasoline on fire and pour water on it, and see what happens. (Disclaimer: DO NOT ACTUALLY DO THIS.) The choice of alcohol over gasoline is a safety issue, and this is the main point to the regulating bodies: water is easy to clean up after, and the stuff you need to stop a gasoline fire is not. (This is also an important consideration when you're running a sporting event and wish to be able to complete it in a reasonable time frame.)

But more powerful, alcohol is not.

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