Entwicklungstrends der Holzenergie und ihre Rolle in der Energiestrategie 2050

Perspectives of biomass combustion and its role in the energy strategy 2050 Wood energy contributes 4% to the total energy demand in Switzerland and is expected to reach 6% by 2020. As a directly storable fuel, energy wood is highly valuable to complement temporarily available solar and wind energy. Since the potential of wood is limited, highly effective applications to substitute fossil fuels need to be prioritised. For this, the energy yield factor is introduced, which reveals that heat and power from wood achieve a high substitution efficiency enabling a reduction of fossil CO2 of up to 90%. Consequently, the unused potential of energy wood should be mobilised for heating, disctrict heat, and combined heat and power (CHP). For these applications, the following developments need to be carried on: small-scale devices with low pollutant emissions by two-stage combustion, stringent execution of air pollution control to avoid inappropriate operation, improvements of grate boilers by aerodynamic optimisation, sectoral fuel conversion, and reduction of fuel NOX emissions by advanced staged combustion. With respect to power from wood, technologies with reduced cost for applications smaller than 1 MWe must be developed, while for low-quality wood fuels, a limited number of highly efficient plants based on Integrated Gasification Combined Cycle (IGCC) is most promising. The findings reveal that the assumptions for the Swiss energy strategy 2050 with a decline of energy wood for heat by 60% and a shift to biofuels are not justified, since wood for heat, power, and CHP achieves higher energy yields with technologies which are available or ready to implementation (IGCC) and economically viable.