Conference Dates

June 16-21, 2019


Hydrothermal liquefaction (HTL) is a promising technology for biofuel production and treatment of organic wastes and biomass. Due to the wet nature of the process where biomass is heated in an aqueous slurry at 350°C and 200 bar, wet biomass and wet wastes are particularly suited for the process. The current study investigates the utilization of wastewater treatment sludges and other organic wastes for the production of sustainable petroleum replacement products. The work has been carried out on a pilot scale continuous hydrothermal liquefaction reactor with a novel oscillating flow system and heat exchanger. The influence of these are discussed in terms of heat recovery and operability of the plant. The reactor was run at 50 L/h with maximum solids loadings of ~25% and short residence times of80% was accomplished, leading to an energy efficient process. During operation of the HTL system, approximately 5 units of energy are created in the form of bio-crude for every unit of energy invested for heating and pumping the slurry (EROI>5). We present and discuss the results of processing diverse samples ranging from high ash (sewage sludge), lignocellulosics (miscanthus) and manure to microalgae. The potential of mixing different waste biomasses such as sludge and lignocellulosics, plastics and lignocellulosics is explored during this research and synergistic effects on bio-crude yields and fuel quality are observed, leading to higher carbon and energy recoveries. Water phase recycling of the HTL process water was employed during the liquefaction of pine where a significant increase in bio-crude yields, energy recovery and energy return on investment could be achieved. Initial results on bio-crude upgrading via catalytic hydrotreatment are also presented, demonstrating the feasibility of the HTL process as a viable pathway towards drop in replacement fuels. The current presentation gives a realistic insight into the processing of diverse biomass feedstocks at pilot scale, showing the potential of the technology while areas for future development and bottlenecks are highlighted.

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