" 1 acre produces 122 bushels of corn per year, which makes
122 x 2.6 US gallons of ethanol, which at 84000 BTU per gallon would
mean a power per unit area of {0.2 W/m^2}; however, the energy
inputs required to process the corn into ethanol amount to
83,000 BTU per gallon; so 99% of the energy produced is used up by
the processing, and the net power per unit area is about
{0.002 W/m^2}. The only way to get significant net power from the
corn-to-ethanol process is to ensure that all co-products are
exploited; including the energy in the co-products, the net power per
unit area is about 0.05 W/m^2."
" 1 acre produces 122 bushels of corn per year, which makes 122 x 2.6 US gallons of ethanol, which at 84000 BTU per gallon would mean a power per unit area of {0.2 W/m^2}; however, the energy inputs required to process the corn into ethanol amount to 83,000 BTU per gallon; so 99% of the energy produced is used up by the processing, and the net power per unit area is about {0.002 W/m^2}. The only way to get significant net power from the corn-to-ethanol process is to ensure that all co-products are exploited; including the energy in the co-products, the net power per unit area is about 0.05 W/m^2."