TOWARDS A STANDARD METHODOLOGY FOR GREENHOUSE-GAS BALANCES OF BIOENERGY SYSTEMS IN COMPARISON WITH FOSSIL ENERGY-SYSTEMS

In this paper, which was prepared as part of IEA Bioenergy Task XV ('' Greenhouse Gas Balances of Bioenergy Systems''), we outline a standard methodology for comparing the greenhouse gas balances of bioenergy sy stems with those of fossil energy systems. Emphasis is on a careful de finition of system boundaries. The following issues are dealt with in detail: time interval analysed and changes of carbon stocks; reference energy systems; energy inputs required to produce, process and transp ort fuels; mass and energy losses along the entire fuel chain; energy embodied in facility infrastructure; distribution systems; cogeneratio n systems; by-products; waste wood and other biomass waste for energy; reference land use; and other environmental issues. For each of these areas recommendations are given on how analyses of greenhouse gas bal ances should be performed. In some cases we also point out alternative ways of doing the greenhouse gas accounting. Finally, the paper gives some recommendations on how bioenergy systems should be optimized fro m a greenhouse-gas-emissions point of view. Published by Elsevier Scie nce Ltd.