## Is corn ethanol water positive?

Is corn ethanol water positive? It depends where you're growing it, obviously, but there are some interesting numbers on EcoWorld, which points out you need between 300 and 900 tonnes of water for each tonne of ethanol grown.
This is very interesting and points to one of the earlier themes of my blog, the effect on water in the environment. It would be good if anyone could help me convert tonnes of water per 300-900 tonnes water per tonne of crop equates to inches of rainfall per year... that would be helpful.

Simon,
One cubic meter of water weighs 2,204 pounds, which I believe is a metric ton. So if 300 cubic meters of water is necessary to grow a ton of corn, then 330 tons (imperial) of water will grow a ton of corn (that's the apparent best case, however).

As for equating this to rainfall, algebraically at least, you would need about 16 inches of rain per year to grow corn, if the corn required 330 tons of water (300 cubic meters) to grow. This rain would have to fall precisely during the growing season at regular intervals, of course, for it to be that easy.
Ed Ring, EcoWorld