Codensification technology as a critical strategy for energy recovery from biomass and other resources - A review

Abstract Driven by the depletion of fossil energy sources and increasing demand for CO2 emission mitigation, the global production of densified biofuel increased dramatically from less than 7 Mt in 2006 to higher than 26 Mt in 2015. Codensification, which bridges biomass densification with other clean technologies through pellet formulation diversification, is attracting attention from researchers worldwide. This paper provides a comprehensive overview of the current lab-scale research framework, the fuel pellet quality evaluation indexes, the latest characterization methods, and novel sources and functionalities of different materials used in codensification. This paper emphasizes the distinct role of codensification as a bridge between existing and emerging biomass conversion routes, waste treatment processes, and fossil resource refinery technologies, and discussed this technology's potential in energy recovery from different resources, including low-fuel-quality biomass and difficult-to-handle wastes/byproducts such as municipal solid waste, sewage sludge, pyrolysis oil and minerals. This work also identified future research challenges, namely, further understanding the particle interaction/binding mechanism during codensification and its effects on the pellet quality, and comprehensively evaluating the social, economic, and environmental impacts of composite pellets during their lifecycle.