Increased ethanol production also affects the world’s water supply. In 2007, there were 150 ethanol plants in the US and 60 more under construction, making it the fastest growing energy industry in the world. At the most basic level, corn-based ethanol plants consume four gallons of water to produce each gallon of fuel, says David Pimentel, an ecology professor at Cornell University. But those four gallons only represent the use of water in end-stage ethanol production. Ethanol is derived from the sugars in corn. When you include the water needed to grow the corn, Pimentel estimates that one gallon of ethanol actually requires 1700 gallons of water. For example, in Nebraska, one of America’s leading corn producers, 2 billion gallons of water were required to produce 676 million gallons of ethanol. According to the Institute for Agriculture and Trade Policy (IATP), there are no publicly available records on water use by ethanol plants in US. The projected relationship between ethanol production and water consumption is shown in Table 3 below.
While many believe that we are experiencing a global water crisis, others predict that the crisis will affect only specific geographic areas. According to Shiklomanov and Rodda, authors of the report “World Water Resources at the Beginning of the 21st Century,” water scarcity varies between different world regions. To measure water scarcity, they compared water use with the renewable water resources of surface water. They found that global water withdrawal was not very high, amounting to only 8.4% of global water resources in 1995. However, since water is distributed unevenly, Asia and Africa experience the greatest variation of withdrawal. For example, 95% of North Africa’s water resources are withdrawn. Water consumption is significantly lower, as Shiklomanov and Rodda estimate that less than 10% of water resources will be withdrawn by 2025.
