We explored costs, environmental impacts and resource use for different types of biomass-based systems and related them to fossil-fuel based systems. Evaluating potential ways to replace fossil fuels with biofuels is complex, as many interacting factors and their development over time have to be taken into account. The focus of interest has been to identify efficient ways to reduce CO2 emissions and oil use through the use of biomass, and to study trade-offs between these two objectives.

We studied opportunities to increase the use of biomass in the energy sector, including potential expansion of current technologies and systems, for example in the district heating sector, as well as the introduction of new technologies, such as gasification-based polygeneration of electricity, transportation fuels and electricity. The potential to increase the biomass use efficiency in pulp and paper industry through energy efficient pulping technologies and black liquor gasification was also studied. Black liquor gasification is a novel technology for the recovery of pulping liquors in chemical pulp mills.

The results indicate that the use of biomass can significantly reduce oil use and CO2 emissions, but there is a trade-off between the reductions in oil use and CO2 emission. Biomass gasification is found to be an important technology to achieve large reductions, irrespective of whether oil use or CO2 emission reduction is prioritised. Oil use and/or CO2 emissions can be reduced efficiently

• if fossil-fuel-fired boilers or electric heating is replaced by district heating from biomass-based combined heat and power generation,
• if electricity or motor fuel is produced from black liquor gasification in pulp mills or
• if wood is used instead of concrete in building construction.

The introduction of plug-in hybrid vehicles appears to be a promising option for reduced CO2 emission and reduced use of petroleum-based fuels in the transportation sector. More fossil motor fuel can be replaced if biomass is used to generate electricity for plug-in hybrid vehicles than if it is used to produce motor fuel.