Use of Life Cycle Assesment to determine the environmental impact of thermochemical conversion routes of lignocellulosic biomass: state of the art.

Abstract: The biomass is a promising way to substitute fossil fuels. Lignocellulosic biomass valorisation is part of second generation technologies. They are interesting in that they imply less competition with food crops for land and water, and they allow for the whole plant to be processed. Moreover, lignocellulose is abundant in cheap and non-food materials extracted from plants such as wood and energy crops. The thermo-chemical route is being considered more extensively, especially the gasification process. This process converts carbonaceous biomass into combustible gases (CO, H2, CO2, CH4, and impurities) called syngas in the presence of a suitable oxidant. The syngas can be converted into a large range of products, such as diesel, via a Fischer-Tropsch process, or methanol, used for producing DME (dimethyl ether), both of which can serve as fuels in traditional motors. Syngas can also be used to produce ethylene and propylene, two building blocks for the chemical industry. Production of these four compounds is specifically investigated. In order to insure that, under the principle of sustainability, the use of lignocellulosic biomass is a viable alternative, its environmental impact must be accurately quantified. The Life Cycle Assessment (LCA) methodology will be used in this regard for the gasification process. The gasification technology will be described, and a state of the art in LCA of the gasification process will be presented. Finally, the need for new research will be established