"Dave Chalton" wrote in message
om...
Thought this may be worth a little discussion, especially for all of
you who are convinced that land is better put to crops for human
consumption than for animals.

I heard it postulated today, in a Crop Mechanisation lecture, that the
power consumption of a powered forage harvester giving a precision (or
metered) chop, working width maybe three metres, in
chemical-energy-required terms, would, in one years use on one farm,
consume enough energy (chemical) to feed 3000 people for a year.

If we feed people 3000 kilocalories a day, 3000 people need about
13,800,000 (3000*3000*365*4.2/1000) megajoules a year. Burning
hydrocarbon fuel we get about 46 megajoules per kilogram, so the
equivalent energy is about 300,000 kg of fuel.

Now I don't know forage harvester from a framistan but does it take 300
tons of fuel a year to run one? According to other posts here nothing
like it by several orders of magnitude.

I wonder if your lecturer has done their own sums?


David