Life Cycle Assessment of American Wheat: Analysis of Regional Variations in Production and Transportation

Life Cycle Assessment (LCA) is a model-based approach to quantify where, and in what form, energy and materials are used in industrial production. The “life cycle” refers to the production of raw materials for fuels, infrastructure and energy conversion equipment, use, maintenance, after life options, and relevant health and social factors. This is sometimes referred to as a “cradle to grave” approach when assessing environmental impacts. Current interest in carbon footprint and environmental impacts of products derived from crops, primarily food and bio-fuels, first requires a detailed life cycle assessment of the agricultural production. American wheat is selected to study the variation in life cycle impacts of an agricultural product that has been aggregated in previous LCAs. All previous studies contain an LCA case study of one species of wheat grown in a specific location. Such a narrow approach is not an accurate representation of the system. This LCA of American wheat differs in the fact that it investigates multiple locations, species, variation in farming practices, fuel use, fertilizer application, and transportation throughout the country in an attempt to be inclusive of the spatial and species variability of wheat production on greenhouse gas emissions. Due to the decentralized nature of American agriculture, an understanding of transportation decisions and resulting impacts are especially important. Results indicate a 101% intra-species and 62% inter-species variation in greenhouse gas emissions of wheat grown in the U.S. However, due to a range of 1440 kg CO2 eq/ha to -1404 kg CO2 eq/ha, sequestration of carbon during cultivation is the most sensitive and variable contribution to life cycle greenhouse gas emissions.