I've been going on about water, quite a bit. I make no apologies for it. If I could just quote from Dr Strangeglove (or how I stopped worrying and learned to love the bomb)
Ripper: Water. That's what I'm getting at. Water. Mandrake, water is the source of all
life. Seven tenths of this earth's surface is water. Why, you realize that.. seventy percent of you is water.
Mandrake: Uhhh God...
Ripper: And as human beings, you and I need fresh, pure water to replenish our precious bodily fluids.
Mandrake: Yes. chuckles nervously
Ripper: You beginning to understand?
Mandrake:Yes. chuckles. begins laughing/crying quietly
Ripper: Mandrake. Mandrake, have you never wondered why I drink only distilled water, or rain water, and only pure grain alcohol?
Mandrake: Well it did occur to me, Jack, yes.
Of course Ripper was mad, but he has grasped the fact that water is vital to life. So has a committee of the US National Research Council , which in a recent report says that
If projected increases in the use of corn for ethanol production occur, the harm to water quality could be considerable, and water supply problems at the regional and local levels could also arise.
And a little later
agricultural shifts to growing corn and expanding biofuel crops into regions with little agriculture, especially dry areas, could change current irrigation practices and greatly increase pressure on water resources in many parts of the United States. The amount of rainfall and other hydroclimate conditions from region to region causes significant variations in the water requirement for the same crop
For biorefineries, the water consumed for the ethanol production process -- although modest compared with the water used growing biofuel crops -- could substantially affect local water supplies, the committee concluded. A biorefinery that produces 100 million gallons of ethanol a year would use the equivalent of the water supply for a town of about 5,000 people. Biorefineries could generate intense challenges for local water supplies, depending on where the facilities are located. However, use of water in biorefineries is declining as ethanol producers increasingly incorporate water recycling and develop new methods of converting feedstocks to fuels that increase energy yields while reducing water use, the committee noted.
This may be a report that Bill Couser over at the Des Moines Register (pretty much required reading I'd say) was responding to in a recent post, and which I stumbled upon yesterday. But Bill, is a farmer in the mid west. He takes a different approach. I can see where he's coming from but I do have an issue with his approach, when he says:
If you would take the annual rainfall in central Iowa (35 inches) over half a section of land (320 acres), that is the amount of water we would use.
Which is fine providing that there's a healthy surplus of corn and that you don't need to irrigate to get the yield up to meet your commitments. If you do find yourself in marginal lands growing crops then you will need to irrigate, as the National Research Council says:
expanding biofuel crops into regions with little agriculture, especially dry areas, could change current irrigation practices and greatly increase pressure on water resources in many parts of the United States
...which is something I'll be watching closely in the coming months.