Choices in calculating life cycle emissions of carbon containing gases associated with forest derived biofuels

Life cycle studies concerning carbon dioxide emissions associated with biofuels from forests may consider emissions originating in the use of fossil fuels and biogenic emissions. When both types of emissions are considered, emission factors are dependent on choices as to time-frame, land-use scenario, allocation of sequestration and fate of sequestered carbon after fuel wood harvesting. Dependent on such choices life cycle emission factors may range from -19x10(2) g (net sequestration) to +68x10(2) g (net emission) CO, per kilowatt-hour generated by burning forest derived biofuels. (C) 2002 Elsevier Science Ltd. All rights reserved.