Emissions of CO2 from biomass production and transportation in agriculture and forestry

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%.