Growth of microalgae with increased calorific values in a tubular bioreactor

In order to use microalgae as a fuel the algae should be of high calorific value and must be capable of growth in large volumes. Chlorella vulgaris and C. emersonii have been shown to grow in a 230 l pumped tubular photobioreactor in Watanabeʹs medium and a low nitrogen medium. The low nitrogen medium induces higher lipid accumulation in both algae, which increased their calorific value. The highest calorific value was obtained with C. vulgaris (28 kJg−1) grown in low nitrogen medium. However, the biomass productivity was 24 mg dry wtl−1 d−1 in the low nitrogen medium which was lower than in Watanabeʹs medium (40 mg dry wtl−1 d−1) and represents a reduced energy recovery.