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The energy available wood, oil, gas coal
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Units and equations are nice, but rather meaningless without any numbers
to go into them. In this section, I give a few very approximate values
for various sources of energy and for various uses.
The Heat Content table shows the heat that is released when various fuels are burned. By "wood," I refer to most wood (ash, oak, pine ...). A log of oak releases more heat than one of pine simply because it is heavier, not because the wood is different. Similarly, a kilogram of petroleum --- whether it be gasoline, diesel fuel, or crude oil --- releases the same amount of heat. However, crude oil is somewhat denser, so a bucketful of crude oil will release more heat than a bucketful of gasoline. Coal always contains mineral impurities. Very poor coal has about 50% impurities, so when you "burn" a kilogram of very poor coal, you are really burning about a half kilogram of "real" coal; the rest is merely weight that becomes ash. Methane is the major component of natural gas. There is no natural supply of hydrogen, but hydrogen could be a manufactured fuel, made by removing it from water. It takes a lot of energy to do so, of course, but at least the hydrogen can be transported. |
Fuel |
MJ/kg |
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80,000,000 = 5,300,000 ´ wood |
Sea rise?
How about firewood?
What about high-level nuclear waste?What
about the Hydrogen Economy?