Life cycle assessment during early development stage of a new bio-ethanol production process

The development of economically feasible and environmentally benign processes for the production of 2nd generation biofuels is an ongoing effort. The production of bio-ethanol from wood (spruce) and wheat straw using a high gravity (high solids content) fermentation process is one concept that is under development. Such a process will lead to lower water use in the process, and consequently to lower energy use. However, high gravity conditions have adverse effects on the micro-organisms and high yields are thus not guaranteed. All this will affect the environmental impact of the process. Life cycle assessment is used to evaluate the environmental impact along the process development path. The life cycle assessment is based on the results of lab experiments that were done for the wood- and straw-based processes. These experiments have been done in order to find appropriate process conditions for obtaining a high yield for ethanol production. Process variables for the straw-based process were the process configuration, type of enzyme, enzyme load and solids content. Experiments for the wood-based process focused on the process configuration and detoxification strategies in order to increase yields. Life cycle inventories were built based on the experimental results, from the extraction of the feedstock material to the plant gate. This paper will discuss the results of the LCA based on the lab experiments for both the straw- and wood-based processes. Comparisons are made with the fossil fuel case and with the ethanol production using first-generation feedstocks and technology