Energetic valorization of wood waste: Estimation of the reduction in CO2 emissions

This paper investigates the potential CO2 emission reductions related to a partial switch from fossil fuel-based heat and electricity generation to renewable wood waste-based systems in Flanders. The results show that valorization in large-scale CHP (combined heat and power) systems and co-firing in coal plants have the largest CO2 reduction per TJ wood waste. However, at current co-firing rates of 10%, the CO2 reduction per GWh of electricity that can be achieved by co-firing in coal plants is five times lower than the CO2 reduction per GWh of large-scale CHP. Moreover, analysis of the effect of government support for co-firing of wood waste in coal-fired power plants on the marginal costs of electricity generation plants reveals that the effect of the European Emission Trading Scheme (EU ETS) is effectively counterbalanced. This is due to the fact that biomass integrated gasification combined cycles (BIGCC) are not yet commercially available. An increase of the fraction of coal-based electricity in the total electricity generation from 8 to 10% at the expense of the fraction of gas-based electricity due to the government support for co-firing wood waste, would compensate entirely for the CO2 reduction by substitution of coal by wood waste. This clearly illustrates the possibility of a ‘rebound’ effect on the CO2 reduction due to government support for co-combustion of wood waste in an electricity generation system with large installed capacity of coal- and gas-based power plants, such as the Belgian one.

► CHP and co-firing in coal plants have the largest CO2 reduction per TJ wood waste.
► At 52% co-firing, coal plants emit 15 times more CO2 per GWh electricity than CHP.
► CO2 reduction of a shift from coal to NGCC plants is equal to that of 52% co-firing.
► Government support for co-firing can trigger a shift from NGCC to coal plants.
► 2% increase of coal-based electricity annihilates CO2 reduction of 10% co-firing.