Indigenous algae: Potential factories for biodiesel production

Abstract

The environmental effects of burning fossil fuels and the increased crude oil prices have triggered increased interest in biofuels. Biodiesel is traditionally produced from oil seed crops, which have lower yields per land area and threaten food security when compared to algae which have high oil yields (~ 90 times more oil per area of land in comparison to the best oil seed crop) and do not require arable land for cultivation. CSIR Biosciences has commenced research in this area with the aim of implementing an algal biodiesel production technology. Lipid producing algal isolates from the United States Department of Energy - Aquatic Species Program (ASP) were obtained to benchmark technology performance. The best strains obtainable were assessed in laboratory studies, the results of which formed the basis of a techno-economic evaluation to identify key variables and parameters influencing the implementation of algal biodiesel production. The model demonstrated a feasible business case (aerial lipid productivity of 26 g/m2/day) at a basic fuel selling price of ~ R8.98, with an IRR and NPV of ~40% and ~R1.3 bn respectively. The model scaled (529 ha) a facility to supply 10% of the mandatory biodiesel inclusion as stipulated by the Department of Minerals and Energy’s biofuels strategy. The model is being applied to drive key research decisions to ensure optimal deployment of resources towards a commercially relevant outcome. The model highlighted the performance of algal strains with high lipid yield and growth rate (aerial productivity) as a key parameter. This led to the commencement of a screening programme to isolate indigenous algal strains capable of high levels of lipid production that would also be suitable to exploit indigenous climatic advantages. Approximately 30% of South African environments favourable for isolating algae have been sampled. Samples were enriched, purified and assessed for lipid content, resulting in a database of indigenous algae. Positive isolates were grown under laboratory conditions to assess growth rates, lipid productivity and yield against Cyclotella cryptica, which was the best strain available from the ASP. The sampling to date has yielded 161 algal isolates of which 52 show lipid production. The first positive isolate was presumptively characterised as Characium spp. Initial comparisons showed that Characium spp. achieved ~70% of the lipid concentration of C. cryptica, albeit in a non-production recipe. The current research indicates strong potential for development and implementation of biodiesel production using indigenous algal isolates and has attracted significant interest from government and commercial partners