A review of densified solid biomass for energy production

Growing concerns over the environmental impact of greenhouse gas (GHG) emissions, uncertainty of future fossil fuel prices, geopolitical instability, and consumer preferences are a few factors driving the development and use of biomass as a source of renewable energy. Government mandates and policy frameworks have further built consensus for effective utilization of sustainable resources for energy. As a result, biomass derived densified solid biofuels have experienced a phenomenal growth in the last decade and are expected to grow by 56% during the three decades from 2010 to 2040. Solid biomass represents the largest share of biomass used for heat and electricity generation. Biomass sources range from agricultural, municipal, and commercial wastes, to forest-litter, and energy crops. Because of the varied nature of these sources, harvesting practices and the cost of transportation, several methods have been developed to densify the biomass. The long-term viability and growth of biobased energy products hinges on the technical innovation and wider societal acceptance of these products. This paper reviews multiple biomass feedstock, processing characteristics, product properties, transportation, and storage options. The paper also discusses the economics of densifying biomass, the impacts to regions where biomass utilization is implemented, outstanding challenges, and national and global trends in biomass utilization.