ABSTRACT
The thermochemical processes developed for biomass energetic valorisation may also be used for algal biomass, keeping in mind the specificities of this type of biomass. Thermochemical processes are usually divided into dry or conventional, and wet or new hydrothermal processes that operate under sub or supercritical conditions. Conventional or dry thermochemical processes are suitable for feedstocks with lower water content, generally below 20%. Conventional thermochemical processes include direct combustion, gasification, liquefaction, and pyrolysis. Besides the energy demands problems associated to the use of algal biomass in conventional thermochemical processes, several studies have been published about algae valorisation through gasification and pyrolysis processes, mainly pyrolysis. Hydrothermal liquefaction could be defined as a thermochemical conversion process in water medium at low/medium temperatures and high pressure conditions. The hydrothermal carbonization has been mainly applied for the treatment of several types of wet biomass, but a few studies on the application of this process to microalgae were found.
