Water Implications of Biofuels Production in the United States (2008) / Chapter Skim
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5 Water Issues of Biofuel Production Plants
5 Water Issues of Biofuel Production Plants
Pages 45-54
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From page 45... ...
Corn Ethanol Ethanol produced from corn kernels totaled 4.5 billion gallons in 2006. Production is growing rapidly in the United States and is expected to reach 6 billion gallons this year, but it still provides only a small fraction of total U.S.
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From page 46... ...
. The overall water balance for a typical bioethanol plant using corn is shown in Figure FIGURE 5-1 Process schematic and unit operations of ethanol production facility from whole corn kernels.
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From page 47... ...
Potatoes, 5-2 sugar cane, sugar beets, or sweet sorghum could be used as a source of starch or sugar for fermentation, and these would alter the water requirements somewhat. Sugar Fermentation of Cellulosic Ethanol Producing ethanol from cellulosic materials such as grasses, crop residues, and wood requires a different process than for corn because they are not rich in starch or sugar.
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From page 48... ...
The process begins with gasification of biomass. Various catalysts are used to obtain a wide variety of potential products including synthesis gas, hydrogen, methane, or mixed alcohols (including ethanol)
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Biodiesel Biodiesel, which in the United States is produced primarily from soybeans, comprises several percent of the nation's total biofuel production. Methanol and caustic (sodium hydroxide)
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Counties west of Chicago, for example, have drawn down the Cambrian-Ordovician aquifer by more than 800 feet of water head since 1850. In southwestern Minnesota, a proposed 100 million gallon per year ethanol plant was turned down by the local water system, which could not supply the 350 million gallons of water per year (~1 mil
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From page 51... ...
This is about 200 times larger than the approximately 4 gal/gal given above for a corn ethanol biorefinery. This indicates that biorefineries themselves generate local, but often intense, water supply challenges, while irrigated agriculture can generate regional-scale problems.
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From page 52... ...
Envi ronmental Protection Agency as a bulk organic chemical production facility. Like ethanol plants, biodiesel plants also have waste streams from cooling tower blowdowns and water treatment reject streams.
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2004. Estimated Use of Water in the United States in 2000.
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From page 54... ...
Photo by Brett Hampton, Agricultural Research Service, U.S. Department of Agriculture
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