Hydrothermal Liquefaction of Algae

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IntroductionThere are many renewable technologies that can produce clean energy but there are still issues surrounding the production of sustainable and renewable liquid fuels and chemicals. In order to meet this need the utilisation of algae has recently emerged as a promising resource. Microalgae in particular are the focus of research towards third generation bio-fuels. Microalgae are very simple aquatic organisms that are able to produce large amounts of lipids, a key precursor in the production of bio-diesel. Hydrothermal liquefaction (HTL) is an attractive conversion technology as it does not require the algal feedstock to be dried before processing; eliminating the large energy loses in many of the more traditional conversion techniques (requiring a dry feedstock) used for first and second generation bio-fuels.AimsConversion of algae feedstocks, utilising mainly microalgal species to crude bio-oil at high yields and maximisation of mass and energy recovery stored in the algae feedstock (transferred to the crude bio-oil)Potential collaboration with other institutes for continuous HTL processing of wet algal slurries (potentially wastewater grown algae) on the basis of HTL experiments carried out in the existing high-pressure batch reactor (with different processing parameters)Production of high quality biocrude oil (in batch and continuous reactor) by application of various processing parameters (temperature, residence time, application of co-solvents and reactive atmospheres, potential extraction of valuable macromolecules such as oils and lipids prior the hydrothermal processing)Recovery of nutrients in the waste (by-product) stream from HTL experiments. These nutrients (particularly nitrogen compounds) can be recycled to the alga bioreactor.Achieve industrially relevant results. Design of Experiment (DoE) approach (taking into consideration all crucial processing parameters) for all laboratory experiments should impact the research output that can be transferred to industrial scales. In order to investigate the potential and viability for hydrothermal liquefaction of algal biomass as a standalone process or part of a larger bio-refinery concept.Application of heterogeneous catalysts suitable for the upgrading of HTL derived bio-crudes (reducing nitrogen content, reducing oxygen content, increasing heating values and modifying various physical characteristics such as viscosity)MethodologyCharacterisation of algae feedstock (as slurries) for hydrothermal processing by elemental and metal analysis, assessment of thermal and chemical properties (thermogravimetric analysis, FTIR analysis, lipid extraction and chromatographic (GC-MS) characterisation)HTL in a small (25 ml) high-pressure reactor.Potential use of continuous liquefaction rig via collaboration with other institutes through the BRISK2 programme.Product separation and characterisation using wide range of appropriate analytical techniques including chromatography, nuclear magnetic resonance spectroscopy, FTIR and elemental analysis).Full characterisation of aqueous streams from HTL experiments for potential recycling of nutrients used in the BioFence reactor (using liquid chromatography and, elemental analysis).Detailed study into application of commonly used industrially relevant catalysts in the upgrading of produced bio-crudes, followed by catalyst fine-tuning and promotion.Detailed data mining and statistical data processing including the use of analysis of variance and principal component analysis. Full computer software based modelling exercise using data from experiments and data from the literature in order to perform a techno-economic evaluation of HTL of algae for the production of bio-fuels.