Microalgae Cultivation and Harvesting for the Production of Biofuels

摘要

Increasing concern over climate change and the impact of greenhouse gas emissions as well as diminishing global oil reserves has pushed research into alternative energy. Reducing the cost of microalgae, a promising source for alternative energy, is a key step in commercialising biodiesel production. Currently avenues such as the use of waste stream cost effective cultivation system and efficient harvesting options are being explored for the common goal of establishing commercially viable microalgae production and utilisation schemes. From reviewing the current progress presented in literature this research has identified several aspects of importance to commercialising biofuel production. After identifying several gaps in the literature covering direct comparison of microalgal biomass production between temperate and hot region, a novel investigation utilising a refined computer model was undertaken to compare upstream cultivation of open systems in both temperate and hot climates. The outcome of which suggested the relative importance of light over temperature for the cultivation of microalgae in an open pond system. This was then explored further experimentally by setting the temperate light intensity, photoperiod and temperature conditions for three months representing summer and winter seasons. The results of this novel adaptation of seasonal highs and lows data of a temperate climate (UK) indicated that a more effective direction of intervention is the investment in additional light-supply in place of a heating-system, which is more than likely to yield higher algal biomass for biofuel production. Finally, an approach was made towards engaging more economical aspects of the process from upstream cultivation of waste stream based nutrients (leachate) with a native microalgae strain for the first time, to downstream dewatering of algal biomass with innovative improvements to energy efficient forward osmosis technology by uniquely assessing microalgae nutrient-based draw solution. The results both indicated the real potential of utilising these cost efficient methods at a lab scale. The ultimate goal of the project was to combine the research efforts for both cultivation (upstream) and harvesting (downstream) to assist in the understanding of the commercial viability of biofuel production from microalgae.