Technical issues in the large-scale hydrothermal liquefaction of microalgal biomass to biocrude

Much of the current knowledge on the hydrothermic liquefaction of biomass to biocrude is on the basis of laboratory benchtop findings, and the step up to industrial scale reactors will require a range of information that is currently either unavailable or insufficient. This work highlights a number of these issues such as the heat of reaction, process heat recovery, optimal reaction time and waste product treatment. Effects of these knowledge gaps on the reactor design, process economics, and impacts on the environment are discussed. Although technologies do exist to deal with some of these issues, their applications are often limited by economic considerations and further studies are required.