A review on optimisation, cost and environmental sustainability of biomass supply and biomass pre-treatment

Establishing an efficient biomass supply chain is important to meet the increasing demand for biofuels and bio-products. However, optimisation of the biomass supply chain is a complex issue due to the multiple layers of elements in the chain and the interactions between these elements. This review includes various elements, such as biomass supply and pre-treatment, in biomass supply chain, and discusses the optimisation strategies for the supply chain. Different types of biomass pre-treatment and conversion technologies with the effect on the supply chain costs, environmental sustainability, and biomass properties, as well as utilisation options for treated biomass and byproducts are also discussed. Biomass treatment technologies reviewed include biomass densification through biochemical, physicochemical, thermochemical and hydrothermal treatments. Cost reduction in biomass transport was found in cases with densified biomass, however, densification and other treatment processes increased carbon equivalent emissions due to additional energy consumption. Advantages exist in biomass pre-treatment, including higher calorific value, and higher bulk and energy density with better combustion behaviour. Biochar obtained from thermochemical decomposition of biomass can be utilised in existing systems, such as substitution of coal with biochar for iron processing, which presented favourable efficiency with lower emissions than coal. Additional costs of biomass-integrated systems, quality of final product and optimal co-feeding ratio of biomass are identified as areas for further study.