Ethanol production water warning from US researchers

Desalination practitioners struggling to reduce the energy consumption of their plants and water engineers fighting shortages might be interested in the following table showing how much water is consumed producing various forms of energy in the USA.

Water requirements for energy production by different processes

Process L/MWh
Petroleum extraction 10−40
Oil refining 80−150
Oil shale surface retort 170−681
NGCC a power plant-closed loop cooling 230−30,300
Coal IGCC b 900
Nuclear power plant-closed loop cooling 950
Geothermal power plant-closed loop tower 1900−4200
EOR c 7600
NGCC-open loop cooling 28,400−75,700
Nuclear power plant-open loop cooling 94,600−227,100
Corn ethanol irrigation 2,270,000−8,670,000
Soybean biodiesel irrigation 13,900,000−27,900,000

a Natural gas combined cycle.
b Integrated gasification combined-cycle.
c Enhanced oil recovery.

The table, derived from a 2006 US Department of Energy report is reproduced in a paper The Water Footprint of Biofuels: A Drink or Drive Issue? by R Dominguez-Faus and Pedro J Alvarez, Rice University, Susan E Power, Clarkson University, and Joel G Burken, Missouri University of Science & Technology, published on 1 May 2009 by Environmental Science & Technology, a publication of the American Chemical Society.

The US Energy Independence & Security Act of 2007 mandated the annual national production of 56.8 million m³ of ethanol from corn by 2015 and an additional 60.6 million m³ of biofuels from cellulosic crops by 2022, a total that represents 15% of the gasoline used in the US in 2006 on an energy basis.

In 2008, ethanol growth vastly outpaced most US industries in 2008, with record amounts of ethanol produced (>34 million m³) and a corn harvest only slightly behind the 2007 record production. Continued growth could have far-reaching environmental and economic repercussions, say the researchers, and it will likely highlight the interdependence and growing tension between energy and water security.