Life Cycle Assessment of Annual and Perrenial Biomass Crops for Ethanol Production

Abstract

The 20th century faces significant increases in the global population and fossil fuel consumption. There have been significant increases in the concentration of GHGs in the atmosphere from human activities. The GHGs build up in the atmosphere and cause the increase in earth’s atmospheric temperature, which leads to many other changes around the world. In addition, increasing greenhouse gas emissions and decreasing fossil fuel sources has been posed new challenges to agriculture, which is agricultural feedstock production, especially due to fertilizer production. The purpose of this study is to investigate the life cycle of producing ethanol comparing an annual and perennial biomass crops, which are corn and switchgrass, respectively. This study employs the use of the full lifecycle model which is known as Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET 2021) model by Argonne National Laboratory to obtain the emission data. According to the results, total GHG emissions are around 0,012 kg N2O/mm BTU; 0,0071 kg CH4/mm BTU; 3,407 kg CO2/mm BTU from the corn to ethanol production per year. However, total GHG emissions are around 0,133 kg N2O/mm BTU; 0,093 kg CH4/mm BTU; 41 kg CO2/mm BTU from the switchgrass to ethanol production per its life time (approximately 15 years). We concluded that the various feedstocks, nutrients, and enzymes will affect the ethanol yield in the well-to-wheel analysis of ethanol production.