Posted by Sherman in Idaho [209.33.95.254] on Tuesday, January 13, 2015 at 13:38:10 :
In Reply to: Energy Ratios posted by Don in Missouri [24.217.215.52] on Monday, January 12, 2015 at 22:11:59 :
It seems to me you're comparing two different things. Yes, the gasoline only contains 80% of the energy content of the crude oil that was in the ground. But that oil as it sits in the ground was free. It cost no one anything to put it there. It's too bad some of the energy was wasted, but that's different from farming where the fuel, land, water, fertilizer, pesticides, etc are all inputs that cost actual money. True, the sunlight is free, but none of those other inputs are.
Maybe a similar comparison would be to compare old-growth lumber to second-growth lumber. Petroleum is like logging the old-growth. The only "waste" is the sawdust that came out of the log in between the boards, and the cost of cutting down the tree and hauling it to the mill, because the log itself, standing on its stump with its slash still attached, cost nothing. Whereas, with second growth you have the cost of planting the tree, possibly fertilizing and spraying it, and waiting 50 years (paying taxes on the land, keeping out thieves, deferring the profit you could have made by selling the land, etc) until you can cut down that tree and make boards and sawdust out of it.
Or maybe another way of looking at it is that if ethanol really does give you 2 units of energy out for every 1 unit you put in, and your 80% figure is right, then petroleum at 80% efficiency gives you 4 units of energy out for each one unit you put in, so it's still twice as good as ethanol.
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