Institute on the Environment, University of Minnesota, 325 VoTech Building, 1954 Buford Avenue, St. Paul, MN 55108, USA.
Bioresour Technol. 2011 Apr;102(7):4747-54. doi: 10.1016/j.biortech.2010.12.041. Epub 2010 Dec 23.
Previously reported water footprints (WFPs) of corn ethanol have been estimated based on the assumption that corn ethanol feedstock could be supplied by the same states where the corn is grown. However, ethanol conversion facilities may choose out-of-state feedstock suppliers depending on the total price of feedstock they have to pay including both the corn price and transportation costs. The purpose of this study is to evaluate the WFPs and total water use (TWU) of corn ethanol considering an optimal allocation of corn with heterogeneous corn feedstock prices across states. The results show that the WFPs of corn ethanol are less than 100 l of water per liter of ethanol (Lw/Le) for all ethanol-producing states based on both the 2008 corn price and transportation costs for rail and truck. Results also reveal that WFPs are very sensitive to the market price of corn and that additional greenhouse gas emissions due to corn trade between states are not significant.
先前报道的玉米乙醇水足迹（WFPs）是基于这样的假设估算的，即玉米乙醇的原料可以由种植玉米的相同州供应。然而，乙醇转化设施可能会根据他们必须支付的原料总成本（包括玉米价格和运输成本）选择州外的原料供应商。本研究的目的是评估玉米乙醇的 WFPs 和总用水量（TWU），同时考虑到各州之间具有异质玉米原料价格的玉米的最优分配。结果表明，基于 2008 年玉米价格和铁路及卡车运输成本，所有生产乙醇的州的玉米乙醇的 WFPs 均小于每升乙醇 100 升水（Lw/Le）。结果还表明，WFPs 对玉米的市场价格非常敏感，而且由于各州之间的玉米贸易而导致的额外温室气体排放并不显著。
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