BioFuels Journal

Myke's Biofuels Blog: Real Science -- Actual Water Use by Ethanol Plants is Comparable to Gasoline Industry

By Myke Feinman, BioFuels Journal Editor

The Wall Street Journal editorialized May 7, gleefully gloating about how everyone is jumping on their bandwagon that ethanol is some horrible monster sucking up precious water resources and increasing the price of food.

We have already discussed how the actual price of food is due to factors like weather, energy (read gasoline and diesel prices) and demand overseas (See "Domestic Ethanol Producers Penalized for Foreigners Who Tear Down Rainforests … What's Wrong With This Picture?" Which was posted on March 4.

I guess what really upsets me about the opinion piece is it quotes horribly incorrect "science."

Here's what the editorial stated:

To create just one gallon of fuel, ethanol slurps up 1,700 gallons of water, according to Cornell's David Pimentel, and 51 cents of tax credits. And it still can’t compete against oil without a protective 54-cents-per-gallon tariff on imports and a federal mandate that forces it into our gas tanks. The record 30 million acres the U.S. will devote to ethanol production this year will consume almost a third of America's corn crop while yielding fuel amounting to less than 3% of petroleum consumption.

And that was just one paragraph.

Okay, first let's examine the last "fact" about 3% of petroleum consumption.

Americans use 140 billion gallons of gasoline each year.

The ethanol industry produced 6.5 billion gallons in 2007 and projections put it at approximately 10 billion this year (that's where the third of America's corn crop figure comes from).

So how is 10 billion just 3% of 140 billion (it's about 7% for those out there who are math-challenged)?

But that is not the only math problem with this single paragraph.

The most damning statement, about slurping up 1,700 gallons of water, is the most absurd of all.

In my opinion, anyone who quotes Pimentel, who is perhaps ethanol's most passionate critic, and who is repeatedly proven incorrect by other scientists time and again, either does not do their homework or just wants to prove a point with erroneous "facts" that fit their argument.

Actual Water Use for Corn

Next, let’s look at the feedstock—corn.

According to the U.S. Geological Survey, an acre of corn GIVES OFF 3,000 to 4,000 gallons of water each day! That is through a process called transpiration.

As the corn plant grows, it takes in water, but also transpires water, releasing MORE WATER INTO the atmosphere than it drinks up from rainfall or irrigation.

But the way, the vast majority of corn in the United States is irrigated with rainwater, not artificial irrigation, according to Researcher Andy Aden of the National Renewable Energy Laboratory (NREL) in Golden, CO.

Aden said that corn that IS irrigated uses 1.2 acre-feet of water per acre of land.

The average corn yield from this is 178 bushels, equating to 785 gallons of water for every gallon of ethanol produced, Aden said.

However, Aden cautioned that the amount of water used will differ from region to region.

Even so, where did Mr. Pimentel arrive at 1,700 gallons of water? Remember, the majority of corn is not irrigated.

Actual Water Use for Ethanol

Okay, so now that we've established corn's water use, what about the ethanol process itself?

The ethanol industry has been evolving rapidly.

A short time ago, it took an average of six gallons of water to produce one gallon of ethanol.

According to Aden, the ethanol industry average is about 3 gallons of water for every gallon of ethanol.

And that number is decreasing as the technology develops, making ethanol less of a water user than gasoline.

The petroleum industry has matured and won't likely be any more efficient a year from now than it is today.

Gasoline sucks up about 2.5 gallons of water for every gallon of gasoline, Aden said.

Back to ethanol. In most cases, a third of the water an ethanol plant uses is recycled back into the process.

There are also plants utilizing "gray" water from nearby municipal water treatment plants as part of the production, freeing up a city's fresh water for other purposes.

Aden said there are some "losses" of water that go up through the plant's cooling tower, as water vapor, but it comes back in the form of rainfall for that corn we talked about above.

"There's a lot of confusion out there around the ethanol water issue and how much is used for ethanol production," Aden said.

Cellulosic Ethanol Water Use

Aden said that cellulosic ethanol water use is similar.

Just for the record, corn was never intended to be the feedstock for a fuel that would totally displace petroleum.

So don't concern yourself that all the corn in the United States will be diverted for ethanol.

In fact, the Renewable Fuels Standard requires that no more than 15 billion gallons be derived from starch-based ethanol (and remember, we’ll be at 10 billion this year).

Corn was always a "bridge" to advanced biofuels, such as fuel made from wood waste, corn stover, corn cobs, sugar cane bagasse, or even cellulose found in landfills.

Note these are all non-food sources.

And contrary to the Wall Street Journal editorial, cellulosic ethanol is not "always just out of reach."

It is already being produced on a commercial basis at Western Biomass Energy, Upton, WY, and there are about two dozen planned pilot, demonstration and commercial plants coming online within the next two years.

So why aren't these facts quoted in the Wall Street Journal article?

All it took for me was a quick call to the NREL.

Maybe, it's because somebody doesn't want you to know the facts.

Thanks for listening, biofuels buffs.

For further information, call the NREL at 303-275-3000.