Life Cycle Assessment of Renewable Energy Production from Biomass

Abstract

Among the different alternatives to conventional fossil fuels, the production of renewable energy from biomass (i.e. bioenergy) is regarded as an interesting option since it involves the valorisation of waste streams, residues and non-food crop biomass. Although a standardised framework regulates the Life Cycle Assessment (LCA) methodology, its application in practice poses some methodological difficulties. This chapter reviews the main methodological issues that a LCA practitioner has to face when it comes to the environmental assessment of bioenergy systems. Despite its complexity, consequential LCA is considered an interesting approach for informing policy-makers and decision-makers about the indirect effect of a specific strategy. In this sense, indirect environmental burdens such as indirect land use change should be included in the study. Moreover, the selection of the system function and system boundaries are other methodological issues that directly affect the results obtained and, therefore, the comparability of LCA studies, intensified in particular in the case of bioenergy systems due to their complexity. In more detail, some bioenergy systems co-produce multiple products, increasing the variability of the functions provided by the system, as well as of the system boundaries chosen to overcome multifunctionality (subdivision, system expansion or allocation). The selection of the appropriate methodology and impact categories, as well as the gaps in characterisation factors, is other methodological drawbacks.