Chapter 8

Chapter 8 – Biomass to Bio-Oil by Liquefaction (pp. 153-166)

Authors:  (Huamin Wang and Yong Wang, Pacific Northwest National Labortatory, Richland, WA, USA, and others)
Significant efforts have been devoted to develop processes for the conversion of
biomass, an abundant and sustainable source of energy, to liquid fuels and chemicals in
order to replace diminishing fossil fuels and mitigate global warming. Thermochemical
and biochemical methods have attracted the most attention. Among the thermochemical
processes, pyrolysis and liquefaction are the two major technologies for the `direct
conversion of biomass to produce a liquid product, often called bio-oil. This chapter
focuses on liquefaction, a medium-temperature and high-pressure thermochemical
process for the conversion of biomass to bio-oil. Water has been most commonly used as
a solvent and the process is known as hydrothermal liquefaction (HTL). Fundamentals of
the HTL process, key factors determining HTL behavior, the role of catalysts in HTL,
properties of the produced bio-oil, and the current status of the technology are
summarized. The liquefaction of biomass using organic solvents, a process called
solvolysis, is also discussed. A wide range of biomass feedstocks have been tested for
liquefaction including wood, crop residues, algae, food processing waste, and animal