Publication Details

Title : Energy consumption and greenhouse gas emissions from enzyme and yeast manufacture for corn and cellulosic ethanol production
Publication Date : October 20, 2012
Publication Journal : http://www.springerlink.com/content/y580l882u044t120/
Authors : Jennifer B. Dunn, Steffen Mueller, Michael Wang and Jeongwoo Han
Abstract : Enzymes and yeast are important ingredients in the production of ethanol, yet the energy consumption and emissions ssociated with their production are often excluded from life-cycle analyses of ethanol. We provide new estimates for the energy consumed and greenhouse gases (GHGs) emitted during enzyme and yeast manufacture, including contributions from key ingredients such as starch, glucose, and molasses. We incorporated these data into Argonne National Laboratory's Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation model and observed that enzymes and yeast together contribute 1.4 and 27 % of farm-to-pump GHG emissions for corn and cellulosic ethanol, respectively. Over the course of the entire corn ethanol life cycle, yeast and enzymes contribute a negligible amount of GHG emissions, but increase GHG emissions from the cellulosic ethanol life cycle by 5.6 g CO2e/MJ.