1) I didn't include the energy necessary to produce ethanol only because the numbers are bad enough even were it 100% efficient. The second reason was to deflect any criticism the calculated costs are inaccurate or inflated.
2) Numerous published estimates of US per capita energy consumption is 8,000 kg of oil per year. A little math yields 4.5 X 10^11 Joules. I assume that number includes the energy required to produce all the goods and services we enjoy.
3) Year-averaged insolation is generally agreed as being 6kW-hrs/m^2/day here in Sunny Southern California where I live. In the US Northwest and the Northeast it is about half that value. A little calculator work gives 8 X 10^9 Joules per year for here.
4) Published data shows an acre of land gives 120 bushels of corn and a bushel gives 2.5 gallons of ethanol. The calculator says that's 7 X 10^7 Joules/m^2/yr.
5) The conclusion is only bleak if human wealth and ingenuity is directed in the wrong direction. Forget about "alternate energy sources", develop nuclear fusion. We are awash in literal oceans of energy; a liter of ocean water contains 2.7 X 10^11 Joules of energy in the form of eminently fusible deuterium. That's equivalent to 300 gallons of gasoline for every gallon of water.
Fossil and nuclear energy is potent only because it is stored energy that can be released quickly and on demand. You cannot flush a toilet a drop at a time. Anyone can check the numbers; I didn't know what they were either. All it took was a calculator, Google and 2 hours out of my fine Sunday morning.
Mariss  |