LIFE CYCLE ASSESSMENT OF A STRAW-BASED ENERGY SUPPLY SYSTEM FOR ORGANIC ARABLE FARMS

摘要

Today’s agricultural industry produces large amounts of greenhouse gases (GHG) from the combustion of fossil fuels during the production activities, for example tractor use and grain drying. Moreover, arable soils emit an important part of the global antropogenic GHG emissions in the form of nitrous oxide (N_2O) and carbon dioxide (CO_2). The aim of this study is to assess the impact on GHG emissions from an organic, arable farm that changes from a fossil fuel-based energy system to a renewable energy system based on straw. Straw is produced on-site as a by-product from cash crop production and can be used in technical systems for production of heat, electricity and fuel that covers the farm use, including the process energy for production of the energy carriers. The system is compared to a reference system, in which the straw is incorporated into the soil and the energy demand is covered with fossil fuels. The results show that the emissions related to energy consumption are eliminated, but that the net soil emissions increase as a consequence of the new production system that includes straw removal, cancelling out most of the gains from the reduction of fossil fuel consumption.