Environmental assessment of biomass-based decentralised polygeneration The case of Swiss Residential buildings

Abstract: Sustainability in the building sector demands remarkable efforts to increase energy efficiency and the share of renewable energies. Biomass-based micro cogeneration systems can help to improve the energy efficiency of residential buildings whiles reducing the over-dependence on fossil energy resources. In this study, the environmental performance of cleaned and upgraded biogas and natural gas in domestic fuel cell and internal combustion engine applications has been assessed. The systems were compared to European grid electricity mix and condensing gas boiler system as the reference. The use of biogas demonstrates clear advantages over natural gas and the reference in terms of climate change and resource depletion. Refined biogas reduces the impacts on resources by approximately 75% and even further with raw biogas. In comparison with the reference, the damage on ecosystems quality from biogas in terms of acidification and eutrophication is substantial, but considering the high global warming potential of methane, the conversion of biomass to biogas appears an opportunity cost. Refining biogas adds up to its cost and environmental burden. In spite of its likelihood to positively or negatively influence consumer behaviour, biomass-based micro CHP demonstrates the potential to create energy self-sufficiency, employment, and income within the society. Biomass digestion presents itself as an alternative waste management strategy.