The cultivation of microalgae for use as an alternative source of lipids for biodiesel production is proposed to offer major advantages in terms of oil yields and land use and maybe capable of mitigating CO2 from manufacturing plant and power stations. However, conventional production of biodiesel requires removal of significant amounts of water before transesterification and this represents one of the major challenges for microalgae biofuels. Hydrothermal processing is an alternative route which can tolerate feedstock with high miosture content and involves processing the microalgae in hot compressed water with or without the addition of catalysts. The energy required to remove the water from algae before transesterification of the lipids is high therefore hydrothermal processing can offer significant savings in energy, efficiency and simplicity. This process effectively simulates nature and produces a low oxygen content bio-petroleum with a high energy density of upto 40MJ/Kg, similar to crude oil. Some of the most productive microalgae in terms of biomass production contain lower lipid content and larger amounts of protein and carbohydrate and not good contenders for biodiesel production. Hydrothermal processing however can convert the lipids, carbohydrates and protein to bio-petroleum increasing yields significantly whilst still being able to recycle nutrients for algal cultivation. The challenges for hydrothermal processing is to produce a bio-petroleum with lower oxygen and heteroatom content (in particular N and S) and increase the yields in the gasoline and diesel range. Previous research by the applicants has shown that using in situ aqueous phase hydrogen donors and heterogeneous catalysts can improve the quality of the bio-petroleum by converting the nitrogen to ammonia and reducing its molecular weight. The proposed research will seek to identify suitable catalysts capable of reducing the nitrogen and oxygen content of the bio-petroleum which in combination with aqueous phase hydrogen donors will provide in situ upgrading to refinery ready bio-petroleum with acceptable levels of N and S. Reactor facilities will be developed for investigating catalyst and additive behavior for a range of microalgae with different biochemical content. Suitable catalysts will be identified with high activity and stability under hydrothermal conditions with the main aim of reducing temperature and pressure requirements thus reducing the associated issues of corrosion, high pressure feeding and reducing the energy demands of the process. A flowing cell reactor will be constructed and a novel micro analytical scale hydrothermal injector will be developed for rapid screening of catalysts and additives. A range of metal doped shape selective zeolites will be evaluated with high stability and high acidity and their activity will be investigated using the developed facilities.

Potential Impact:
Who will benefit from this research The production of high quality hydrocarbons from microalgae will have benefits to the global world economy and provide an alternative feedstock for automotive and aviation fuels and for the production of chemicals. Development of this technology will benefit producers of fuels such as petroleum companies, end users such as the aviation industry, chemical manufacturers over a wide range of sectors and society as a whole. The use of microalgae for CO2 mitigation and production of transport fuels will contribute to meeting UK emission targets and the renewable transport obligation. Specific to microalgae is the potential for production of ammonia which will be of interest to the fertilizer industry. The development of new catalysts, stable and active under hydrothermal conditions will be of interest to catalyst manufacturers and have the potential for generating significant IP. The development of facilities for the investigation of hydrothermal processing of microalgae will have academic beneficiaries which include the University of Leeds for the potential generation of IP, the applicants themselves and the staff and students receiving training through this research. The project will provide training for a PhD student and support the career development of a PDRA. The research community investigating hydrothermal processing of biomass will benefit from the dissemination of research and include research groups in the UK, Europe and Asia. How will they benefit from this research The cultivation of microalgae has the potential for mitigating CO2 and for increasing biomass yields significantly per hectare of available land thus contributing to tackling climate change. The hydrothermal processing of microalgae has the potential to significantly reduce the energy consumption associated with drying microalgae improving its economics and carbon footprint. Hydrothermal processing converts the whole algae into bio-petroleum and therefore does not require the cultivation of high lipid microalgae removing two major barriers from the development of algal biofuels. The development of catalysts capable of producing hydrocarbons low in heteroatoms will provide a feedstock of interest to a wide range of end users from chemical manufacturers to fuel producers which can be upgraded using existing technology without deactivating refinery catalysts. Microalgae can convert convert nitrogen from sources such as NOx to ammonia which can be used for nutrient recycling, the production of fertilizers or other products. Hydrothermal processing will allow industry to mitigate CO2 and convert waste streams into a source of hydrocarbons and ammonia. What will be done to ensure that they have the opportunity to benefit from this research Partnerships will be developed with stakeholders and the research findings will be disseminated via conference, high impact peer reviewed journals, workshops and networks (such as UK Algal Biomass Network, and Supergen Bioenergy). A number of visits to key leading research groups are planned to develop links in Japan, the US and in Europe. A workshop will be organized on hydrothermal approaches for processing biomass through the biomass research forum as part of the Supergen engagement and industry will be invited from a wide range of sectors. The research will consider a number of case studies suitable to different industrial end users and prepare fact sheets for dissemination at workshops and conferences.