Monday, March 21, 2011

The Way I Figure it...

Much has been argued about the water budget for ethanol production.  The industry argues that it's not that bad - a mere 3 to 4 gallons of water for every gallon of ethanol.  Well, like everything else, it depends on what you account for.  The way I figure it...

Corn in our area (Northwest Kansas) will take an average of 150 AF of water to grow an average of 225 bushels on a 120 acre circle - a very typical arrangement - here.  But only about 80% of that pumped water is consumed in the growing process (the rest returns to the aquifer system - yes, this is the consumptive water use mantra AGAIN!!)  This means that 48,877,650 gallons of water are pumped, of which 39,102,120 gallons are used.  With our average yields of 225 bushels of corn per acre, this means that 27,000 bushels of corn are produced for the 39,102,120 gallons of water.  This is 1,448 gallons of water for each bushel of corn.

The industry reports about 2.75 gallons of ethanol are produced by each bushel of corn, meaning that it takes .36 bushels of corn to produce each gallon of ethanol.  This means that it takes about 525 gallons of water to grow the .36 bushel of corn it takes to make 1 gallon of ethanol. 

Our local ethanol plant here in NW Kansas is efficient and uses 3.6 gallons of water in its process to make each gallon of ethanol.  This means it takes about 150 times the amount of water to grow the corn it takes to make 1 gallon of ethanol than it does to process that .36 bushel of corn into ethanol.

However, one has to ask whether or not the corn would be grown if ethanol were not being produced?  Probably a very high percentage of it would be, so what's the difference?  Moreover, even if no corn would be grown, it's just as likely that some other irrigated crop would be grown with the same water.  Again, what's the difference?  So, while I personally think the water use needed in corn production for ethanol is significant, I'm also thinking that ethanol is NOT the cause of our water dilemmas here in GMD 4.  We had regulations in place before the ethanol push, so no new land and water use came into production because of the push.  It's the new irrigated land that would have made our water supply problems worse.  Of course, it didn't help matters much, either. 

I guess what I'm saying is, if you're concerned about the water use associated with ethanol, the only way to truely save this water would be to revert these irrigated corn acres being used for ethanol back to dry land production.  I'm also saying that this is highly unlikely to happen, so maybe the chore of figuring water use is pretty pointless.  But it does bother me a bit to listen to the pro and anti ethanol factions discuss water use numbers that are so very far apart. And it confuses everyone who is trying to understand the issues.

Yeah, I know the real water footprint of ethanol production is even more complicated than this, but it seems to me to be an unsolvable argument when no one has any idea what the production choices will actually be otherwise.  These new production choices will be the key to making our water supply problems better or worse, and they'll vary from place to place based on local economics and regulations.

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