Ethanol gets hosed

Researchers from the University of Texas at Austin say not enough people are considering whether they have the necessary water resources to meet the needs of new biofuel technologies.

Energy analysts Carey King and Michael Webber calculated the water usage of several fuels being developed in the United States as alternatives to petroleum-based gasoline and diesel.

Conventional ethanol and soybean-oil biodiesel from irrigated fields were among the biggest water culprits in the study, which followed their research earlier this year showing the high water-cost of plug-in electric vehicles. Irrigated corn accounts for 13 percent of the U.S. corn crops, according to the U.S. Department of Agriculture.

“We looked at it just from the irrigated water perspective, a proxy for, 'Are you in a place where it rains or not?'” King, a research associate at the University of Texas Center for International Energy and Environmental Policy, told the Cleantech Group. 

King and Webber looked both at the amount of water consumed—water taken from a surface water or groundwater source and not returned—and water withdrawn, used in a process and then returned to the source.

Their study appears in the journal Environmental Science & Technology. Some of their findings include:

• Typical gasoline consumes up to 0.14 gallons of water per mile and withdraws up to 0.63 gallons of water per mile.
• Converting coal into fuel via the Fischer-Tropsch method (coal gasification) consumes up to 0.58 gallons of water per mile and withdraws up to 0.43 gallons of water per mile.
• Biodiesel from irrigated soybean fields consumes as much as 24 gallons of water per mile and withdraws up to 26 gallons of water. If the biodiesel was made from non-irrigated soybean fields, it would consume up to 0.02 gallons of water per mile and withdraw up to 0.12 gallons of water per mile.
• Ethanol (E85) made from corn grown in irrigated fields consumes up to 62 gallons of water per mile and withdraws as much as 110 gallons of water per mile. Ethanol produced from corn grown in non-irrigated fields on the other hand, consumes up to 0.35 gallons of water per mile and withdraws up to 0.56 gallons of water per mile.
• Hydrogen produced via electrolysis consumes as much as 0.42 gallons per mile and withdraws up to 13 gallons of water per mile.
• Hydrogen derived from natural gas consumes up to 0.06 gallons of water per mile and withdraws up to 0.07 gallons of water per mile.

King said that the study results aren’t meant to indicate that one technology is better than another. Rather, he said, the work is “a more current snapshot in time” of how water-intensive the processes used to produce and use these alternative fuels are.

And not all alternatives are presented in the paper. The biofuels he and Webber considered are only derived from corn or soy, the major feedstocks in the United States. Non-food crops such as jatropha and miscanthus weren’t studied, nor were algal biofuels and biobutanol.

“We had to draw the line somewhere,” King said.

Back in June, King and Webber released a paper noting that if Americans switched to driving electric cars, they’d consume three times more water than if they drove internal combustion engine vehicles.

People thought, “King and Webber are against plug-ins,” King said. He’s hoping the new study won’t cause a similar reaction.

“It depends on the point of view people take,” King said, noting that people historically considered transportation took only 2 percent to 3 percent of water consumption and didn’t think too much about it. Increasing interest in water supplies may change that now, he said.

Some companies have been factoring in the water consumption issue. San Francisco, Calif.-based ECO₂ Plastics (OTC: ECOO), for example, has developed a waterless process of cleaning and recycling plastics. Plastic recycling plants are estimated to use as much as 100,000 gallons of water a day (see The dirty little secret of plastic recycling).

According to the U.S. Geological Survey, Americans used 408 billion gallons of water a day from freshwater and saline-water sources in 2000. Of the total water supply, 195 billion gallons of water, mostly from saline water sources, were used to cool power plants. Another 137 billion gallons of fresh water went to irrigation needs. California, Texas and Florida used 25 percent of all the water withdrawn in 2000.

The U.S. Environmental Protection Agency has projected that 36 states will face water shortage issues by 2013, and global water shortage concerns have spurred investment into the water industry (see A new market for advanced water technologies). Last month the EPA and Overland, Kan.-based engineering company Black & Veatch announced they were looking into water filtration and desalination technologies (see U.S. water challenges spark research efforts).