A comprehensive review on densified solid biofuel industry in China

Biomass is a sustainable and renewable energy source with relatively low pollution emissions. It can be transformed into gaseous, liquid and/or solid biofuels as well as other raw chemical materials and products. Among the biomass conversion technologies, densified solid biofuel is one of the means that is storable and transportable with low heating cost. In order to achieve the target of reducing the amount of carbon dioxide emissions per unit of Gross Domestic Product (GDP) by 40–45% until 2020 as set at the United Nations Framework Convention on Climate Change (UNFCCC), and realize the goal of China׳s 12th Five-year Plan (2011–2015) for the development of biomass energy, given that carbon emissions will peak in 2030 as estimated in 2014 during Asia-Pacific Economic Cooperation Conference, China should vigorously develop densified solid biofuel, so as to sharply minimize the unorganized burning of crop residues. This paper introduces the current status of China׳s densified solid biofuel and the industry in following aspects: (a) the classification of densified solid biofuel; (b) development of densified solid biofuel industry; (c) molding technology of densified solid biofuel; (d) characteristics of densified solid biofuel combustion; (e) the problems faced during molding, handling, transportation and storage; (f) existing Chinese standards for densified solid biofuel and the assessment of densified solid biofuel; and (g) market analysis and perspectives of densified solid biofuel and the industry. Moreover, this study provides a comprehensive overview of the development of China׳s densified solid biofuel and the related industry, proposes some recommendations for further development of the industry for domestic and international biomass energy researchers as well.