Abstract:
This document describes the methodology and data sources for the “Analysis of lifecycle water requirements of transportation fuel: corn based ethanol – model version 1.1”. The model estimates water requirements for ethanol from corn grain and corn cob (crop residue) based on default or user inputs of crop evapotranspiration, pre-irrigation requirements for salt leaching and crop establishment, irrigation methods and the efficiencies of conversion technologies, and projected crop yields. Water requirements also depend upon procedures adopted for calculating co-product credits at various stages of the lifecycle. The model characterizes water requirements in terms of withdrawal and consumption; and source – ground water, surface water, precipitation, and soil moisture.

The spreadsheet based model is available at
http://www.its.ucdavis.edu/download/UCD-ITS-RR-10-11.xls

The model is part of a series exploring water footprint of future transportation fuels including bio-fuels and electricity. Other models currently under development examine the lifecycle water requirements of electricity from geothermal resources and concentrated solar power.