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by elago
2177 days ago
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According to the U.S. Department of Agriculture, the U.S. has 434,164,946 acres of “cropland”—land that is able to be worked in an industrial fashion (monoculture). This is the prime, level, and generally deep agricultural soil. In addition to cropland, the U.S. has 939,279,056 acres of “farmland.” This land is also good for agriculture, but it’s not as level and the soil not as deep. Additionally, there is a vast amount of acreage—swamps, arid or sloped land, even rivers, oceans, and ponds—that the USDA doesn’t count as cropland or farmland, but which is still suitable for growing specialized energy crops. Of its nearly half a billion acres of prime cropland, the U.S. uses only 72.1 million acres for corn in an average year. The land used for corn takes up only 16.6% of our prime cropland, and only 7.45% of our total agricultural land. Even if, for alcohol production, we used only what the USDA considers prime flat cropland, we would still have to produce only 368.5 gallons of alcohol per acre to meet 100% of the demand for transportation fuel at today’s levels. Corn could easily produce this level—and a wide variety of standard crops yield up to triple this. |
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A decade ago biofuels were my first thought. The maths simply don't add up. Our options are far less energy per person, far fewer people, other sources of energy, or, most likely, some combination of these.
The highest claimed yields are for algae, at a rather improbable 1,000 gal/(acre * year):
[Y]ou might consider floating the algae offshore, along the Pacific and Atlantic costs. It's roughly 1,300 miles from San Diego, CA to Port Angeles, WA, and 1,800 miles from Homestead, FL to Lubec, ME. Dividing our 443,000 square miles by those two added together, we find we'd have to extend our grow region some distance off-shore. That is, 143 miles off-shore. The full length of both coasts.
Or perhaps you'd prefer to re-purpose the Gulf of Mexico. Its total area is about 600,000 mi2, we'd need about 3/4 of it dedicated to algae growth.
https://old.reddit.com/r/dredmorbius/comments/2cvap7/the_int...
Tom "Do the Math" Murphy:
https://dothemath.ucsd.edu/2011/11/the-biofuel-grind/
https://dothemath.ucsd.edu/2011/08/garbage-in-garbage-out/
The late David MacCay's Alternative Energy Without the Hot Air gives a comprehensive breakdown for the UK of alternative energy options. Again, the picture is bleak.
https://withouthotair.com
The takeaways are we use a lot of energy and there are a lot of us.