Hydrothermal liquefaction (HTL) is
a promising technology
for converting
abundant organic wastes into fuels. Previous techno-economic analyses
(TEAs) of HTL have been used to estimate the minimum fuel selling
price (MFSP) of biofuel products, but these analyses often assume
a bespoke plant design where each plant operates under unique process
conditions and neglect transportation costs. However, transportation
costs must be included in realistic TEAs, and further, a mass-produced
fixed-scale modular plant design approach may be more effective than
case-by-case plant design, provided that there is sufficient market
capacity to benefit from modularization. This study estimates fuel
price behavior in the presence of transportation costs and benefits
stemming from modular plant design. This analysis indicates that a
modular process capable of handling 60 dry tons per day (DTPD) is
optimal, resulting in a ∼25% reduction in MFSP (from $4.70/GGE,
fully upgraded) at complete market feedstock utilization compared
with case-by-case design. The associated cost reductions are attributable
to learning benefits and modularization. Several HTL deployment “roadmaps”
are then explored, with each roadmap consisting of different periods
of case-by-case design followed by adoption of a modularized approach.
A period of nonmodular industry growth up to market saturation of
∼7% followed by implementation of modular plant design strikes
a balance between the investment risk and learned cost reductions
associated with modular plant design. However, if bespoke plants built
during this period of nonmodular growth saturate more than 23% of
available feedstock, learned cost reductions are significantly diminished.
This study points to the potential benefits of modularized and decentralized
waste-to-energy processes when the modularization follows an optimal
deployment strategy.