Ethanol: By the Way, You'll Need Water

It's a longstanding joke among people who sell land. The closing is over, signatures secured, the deed transferred, and after a final handshake, this off-hand comment is delivered over-the-shoulder:

By the way, you'll need water.

That's become the story of corn ethanol in the US, and it's no laughing matter.

Last year's energy bill requires 36 billion gallons of annual biofuels production by 2022 -- probably about half of them from corn. The measure, largely a giant gift to agribusiness interests, appeared to address both environmental and energy security issues, while really doing neither. And now what's surfacing is a threat to the nation's water security.

The question of water, like oil supply, takes us deep underground, where deposits of sand, gravel and silt store water in ancient aquifers. This supply of groundwater, which is what half of the nation relies on for drinking, is not inexhaustible.

Take the Mahomet aquifer in Illinois, for example, which spans 15 counties and supplies 100 million gallons of groundwater a day for public use, industrial supply, and irrigation. Here's what one paper on the web site of the Mahomet Aquifer Consortium had to say:

As with other deep aquifers, the greatest threat to the continued viability of the Mahomet Aquifer comes not from contamination but overpumping; that is, removing water faster than it is replaced. Water consumption from the aquifer now averages 84 million gallons a day.....

Recent studies of the aquifer by scientists from the ISGS and the Illinois State Water Survey indicate that well-water levels around Champaign and Urbana are dropping.....the surplus could vanish with the addition of a few high-demand users.

Like an ethanol plant or two. Or a dozen. Here's a snapshot of the demand a single plant can place on water supply, from the Economist:

Officials in Tampa, Florida, got a surprise recently when a local firm building the state's first ethanol-production factory put in a request for 400,000 gallons (1.5m litres) a day of city water. The request by US Envirofuels would make the facility one of the city's top ten water consumers overnight, and the company plans to double its size. Florida is suffering from a prolonged drought. Rivers and lakes are at record lows and residents wonder where the extra water will come from.

In the biofuel heartland, pressure will be even greater. That's why Missouri residents went to court to stop an ethanol plant projected to draw 1.3 million gallons of water a day from the Ozark aquifer, as have residents of other states. And it's not only the ethanol plants that are the water hogs. Increased crop production to feed the ethanol plants consumes even more water resources.

A study on biofuels and water published by the Institute for Agriculture and Trade Policy (IATP) provides the following illustrative estimate:

For Iowa, in the heart of corn production in the U.S., the water use (associated with crop water requirement) for producing a gallon of ethanol has been calculated to be between 1081 and 1121 gallons of water. However in fully irrigated agriculture, crop water use increases substantially.

For example for corn grown in Southwestern part of Nebraska, where it is irrigated, the average water use (associated with crop water requirement) for producing a gallon of ethanol has been estimated to be about 1568 gallons of water.

The Ogallala Aquifer, also known as the High Plains Aquifer, is a vast aquifer located beneath portions of eight states on the Great Plains. It waters one fifth of irrigated land in the US. BBC identifies it as water hot spot:

The aquifer was formed over millions of years, but has since been cut off from its original natural sources. It is being depleted at a rate of 12 billion cubic metres a year – amounting to a total depletion to date of a volume equal to the annual flow of 18 Colorado Rivers. Some estimates say it will dry up in as little as 25 years.

It's all enough to drive a person to drink. It's not exactly what Congress had in mind, but if this keeps up, we just might have to start drinking some of all that grain alcohol -- instead of putting it in our cars.

Related Stories

Climate Change's Most Deadly Threat: Drought (Christian Science Monitor)

Bush To Clean Energy Leaders: Let Them Eat Corn

Corn Ethanol Boom in US, Hunger Worldwide

Coal-Fired Ethanol Plants? Really.

The Few Winners and Many Losers of Biofuel Mania

Connect the Dots: Climate, Energy and Farming

Before We Get Drunk on Ethanol, Let's Make Sure We Get It Right (Watthead)

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