A toolbox to tackle the technological and environmental constraints associated with the use of biomass for energy from marginal land

Biomass is a renewable and sustainable feedstock for energy, contributing to diversify the energy supply, to reduce the dependence on fossils fuels, and to greenhouse gas (GHG) mitigation. Nevertheless, the mandatory renewable energy targets are also contributing to a higher demand on biomass, which increases competition for land, threatening food security. Therefore, production of biomass in marginal soils is being recommended to lessen land use change ethical issues linked with competition with food crops. But, the marginal conditions of the soils (e.g. contaminated soils) may hinder the technological and environmental performance of the bioenergy production chain. Despite the potential amount of energy content, yields are reduced, and biomass characteristics may change, affecting processes and equipment’s chosen. Reduced yields force the energy balance to decrease, once outputs will be lower, decreasing the amount of fossil energy saved/conserved. Moreover, lower yields imply a lower abatement of GHG, due to lower carbon sequestration by the biomass, which may limit future applications of biomass according to the European policies. In addition, the increment of nitrogen, potassium and ash content in the biomass, induced by the decreased production, may harm the equipment’s performance, and implicate in the environmental life cycle benefits driven by the biomass use. In this scenario, the main goal of this study is to provide an identification of the technological and environmental constraints and challenges associated with the use of biomass obtained from marginal soils through thermochemical processes and to provide a toolbox to tackle it. Implementation pathways will be presented based on a decision tree, supported by the current knowledge.