Microalgae as biodiesel & biomass feedstocks: Review & analysis of the biochemistry, energetics & economicsElectronic supplementary information (ESI) available: Appendices I-IV. See DOI: 10.1039/b924978h

• Main Authors: Williams, Peter J. le B, Laurens, Lieve M. L
• Format: Article
• Language: English
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/b924978h

Following scrutiny of present biofuels, algae are seriously considered as feedstocks for next-generation biofuels production. Their high productivity and the associated high lipid yields make them attractive options. In this review, we analyse a number aspects of large-scale lipid and overall algal biomass production from a biochemical and energetic standpoint. We illustrate that the maximum conversion efficiency of total solar energy into primary photosynthetic organic products falls in the region of 10%. Biomass biochemical composition further conditions this yield: 30 and 50% of the primary product mass is lost on producing cell protein and lipid. Obtained yields are one third to one tenth of the theoretical ones. Wasted energy from captured photons is a major loss term and a major challenge in maximising mass algal production. Using irradiance data and kinetic parameters derived from reported field studies, we produce a simple model of algal biomass production and its variation with latitude and lipid content. An economic analysis of algal biomass production considers a number of scenarios and the effect of changing individual parameters. Our main conclusions are that: (i) the biochemical composition of the biomass influences the economics, in particular, increased lipid content reduces other valuable compounds in the biomass; (ii) the "biofuel only" option is unlikely to be economically viable; and (iii) among the hardest problems in assessing the economics are the cost of the CO 2 supply and uncertain nature of downstream processing. We conclude by considering the pressing research and development needs. A major and fundamental review is made of the potential yields and economics of biomass and biolipid from microalgae.