Net CO2 emissions have been calculated for the production and transportation of biomass in Swedish agriculture and forestry, using fossil-fuel-based energy inputs. An analysis of how a transition from a fossil-fuel-based energy system to a CO2-neutral biomass-based system would affect the energy efficiency in biomass production and transportation, has also been carried out. Production and transportation of short-rotation forest (Salix), straw, and logging residues exhibited the lowest CO2 emissions per unit energy delivered, equal to about 50% of those from perennial ley crops and 10 to 30% of those from annual food crops. Compared with CO2 emissions from a complete fuel-cycle for coal, net emissions of CO2 from Salix production, including transportation 50 km by truck, are 35 to 40 times lower when fossil-fuel inputs are used. Future increases in yield and technological development are estimated to reduce net CO2 emissions from biomass production by 30 to 50% in a fossil-fuel-based energy system around the year 2015. A transition from a fossil-fuel-based, to a CO2-neutral biomass-based energy system around 2015, is estimated to increase the energy input in biomass production and transportation by about 40% and 20%, respectively, resulting in a decreased net energy output from biomass production (including transportation) by about 4%.
