Net environmental impacts of low-share wood pellet co-combustion in an existing coal-fired CHP (combined heat and power) production in Helsinki, Finland

Abstract

The EU's energy sector depends heavily on fossil fuels, which contribute to climate change. This is why climate mitigation targets for energy production have been set, including an increased biomass use requirement. In Finland, biomass is commonly utilised but its capital, Helsinki, is still dependent on fossil fuels. With the ambition of becoming climate neutral by 2050, Helsinki is testing, inter alia, low-share wood pellet and coal co-combustion in a CHP (combined heat and power) plant.The objectives of this paper were to assess the net environmental impacts of the co-combustion and changes in urban air quality connected to pellet transport, and to identify environmental hotspots relevant to possible future higher-share co-combustion. The applied methods were screening LCA (life cycle assessment) and fine particle dispersion modelling.The results prove that low-share wood pellet co-combustion in CHP production leads to net environmental impact reductions and does not deteriorate air quality in the urban environment. If higher-share co-combustion were to be implemented, the environmental hotspots to focus on would be the operational issues of a power plant and the origin and sustainability aspects of wood pellet production.