Preliminary study on the economic assessment of culturing Nannochloropsis sp. in Egypt for the production of biodiesel and high-value biochemicals

The economic feasibility of growing Nannochloropsis sp. at the commercial scale was evaluated for the production of biodiesel and co-products. A local isolate of Nannochoropsis was grown in (6) 200-L raceway ponds at Alexandria University wherein cultures reached maximum cell concentrations similar to 4-6 x 10(7) cells/mL (0.63-0.88 g/L dry weight) and a peak biomass productivity of 0.09 g/L/day during mid- to late-log growth. Areal productivity was estimated at 17.65 g/m(2)/day when ponds were operated on a semi-batch schedule, harvesting 50% every 2 days and recycling 60% of the media. Areal productivity was estimated around 10.3 g/m(2)/day for batch schedules. Late-log cultures harvested from all ponds yielded 10 kg of wet algal paste, which was reduced to 1.05 kg of dried algal powder. The biomass was composed of valuable co-products approx. 14.0% carbohydrate, 37.3% protein, 0.01% chlorophyll-a, and 0.02% carotenoids (w/w). Total lipid made up 38% of the biomass (w/w); 34% of the biomass was determined to be neutral lipid which are transesterified to biodiesel and 4% are polar lipid. Fatty acids from glycerolipids were quantified by gas chromatography-flame-ionization detector (GC-FID) as fatty acid methyl esters (FAMEs) revealing carbon-chain lengths from C6 to C22. A preliminary economic evaluation was conducted to determine the feasibility of constructing commercial-scale algae biodiesel production facilities in Egypt. The return on investment (ROI) of the current economic feasibility study for biofuel production alone was 22% after considering the market prices of the biodiesel, cake, and glycerol by-products. Based on this assessment, additional high-value products are needed to improve the ROI. Noting that the valuable co-products are considered as added cost in the biomass left after biodiesel production.

Automated summary

The economic feasibility of commercial-scale Nannochloropsis sp. cultivation for biodiesel production and co-products was evaluated. The study showed that under appropriate conditions, high cell growth and productivity were achieved. However, additional high-value co-products are needed to improve the return on investment.