51. Lignin: Application in Renewable Energy

This chapter delves into the promising role of lignin, a complex polymer found in plant cell walls, as a renewable energy source. It begins by discussing the chemical structure of lignin, which is composed of three main monomers: p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), each with varying degrees of methoxylation. The chapter then explores different methods for isolating lignin from other plant components, focusing on chemical processes such as the kraft process, sulfite pulping, and organosolv process. Each method's impact on lignin's structure and properties is examined, with particular attention to the environmental implications. The core of the chapter is dedicated to the thermochemical conversion of lignin into various biofuels. It covers torrefaction for producing solid fuel pellets, fast pyrolysis for bio-oil, and conventional gasification for syngas and hydrogen. The chapter concludes by emphasizing the potential of lignin valorization in promoting decarbonization and a net-zero economy, providing valuable insights for professionals in the renewable energy sector.