In addition, a life cycle assessment (LCA) based on a conceptual
biomass liquefaction process is also conducted and presented. Life
cycle assessment is a systematic method used to evaluate the
environmental impacts of a technological system throughout its
life cycle [28]. It has been employed in a wide range of applications. For example, Cherubini and Ulgiati compared the LCA of a
biorefinery concept generating bioethanol, bioenergy and biochemicals from corn stover and wheat straw [29]. Woon and Lo
performed LCA on the analysis of environmental hotspots of proposed landfill extension and advanced incineration facility [30].
Amor et al. integrated electricity supply dynamics to refine the
LCA results on a renewable distributed generation system [31].
Ng et al. performed LCA to examine the impacts of different
domestic wastewater streams and the effectiveness of two water
conservation policies [32]. However, to the authors’ best knowledge, the environmental impacts of bio-oil production from biomass via hydrothermal liquefaction have not been widely
reported in the literature, although there are LCAs reporting the
comparisons between several choices of conversion technologies.
LCA of eight types of advanced thermal technologies utilizing
pyrolysis and gasification for waste treatment were conducted by
Khoo [33]. Meanwhile, the LCA of biofuel production from corn
stover fast pyrolysis and subsequent hydroprocessing and upgrading process was reported by Dang et al. [34]. Liu et al. [35] and
Fortier et al. [36] conducted LCA studies related to the hydrothermal liquefaction process of algae and microalgae, for biofuels and
bio-jet fuel production, respectively. Due to the limited LCA study
on the hydrothermal liquefaction of lignocellulosic biomass for
bio-oil production reported, it is vital to conduct a LCA study to
gain preliminary insights into the environmental impacts associated with the conceptual process of oil palm biomass liquefaction
for bio-oil production.
2. Materials and methods