ABSTRACT Heterotrophic microalgae for biofuel production * lucas.rye@csiro.au; Ph. +61 3 9239 4418; Fax. +61 3 9239 4444 Limited biomass feedstock availability is expected to restrict industry uptake of bio-refined transportation fuel (Rye et al. 2010). This work seeks to investigate the potential for microalgae to provide Australia’s commercial aircraft fleet with a secure, environmentally sustainable alternative fuel feedstock through a triple bottom line analysis. Cultivation of microalgae as a second generation feedstock for bio-oil production – which may then be upgraded to jet fuel using hydroprocessing techniques – has gained much interest in recent years with the literature citing high yields, rapid growth rate, marginal land utilisation and sustainable water usage (seawater or wastewater) as some of the key benefits. The vast majority of the research / start-up organisations are focusing on cultivation of phototrophic algae for bio-oil production (photosynthesis). Phototropic raceway cultivation however, provides low biomass dry weight yield per litre of cultivation medium, with values of 0.3 gl-1d-1 (i.e. 20 gm-2d-1) frequently cited. This dilute culture throughput significantly increases processing cost (i.e. harvesting, dewatering and oil extraction) and thus represents a significant economic barrier if the system is designed to produce only low value bio-oil. Cultivation of heterotrophic microalgae – culture grown in the dark using glucose as feed – has the potential to provide significantly higher biomass yields according to figures published by Wu et al. Tsinghua University group. The most recent work from this group established an equivalent bio-oil yield of 8.3 ml per cultivation litre per day (Yan et al. 2011). Heterotropic algae as a source of bio-oil feedstock for jet fuel production thus warrants further investigation in order to establish the economics and sustainability of this pathway. References: |