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 2301 pumped tubular photobioreactor in Watanabe's 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 kJ g(-1)) grown in low nitrogen medium. However. the biomass productivity was 24 mg dry wt 1(-1) d(-1) in the low nitrogen medium which was lower than in Watanabe's medium (40 mg dry wt 1(-1) d(-1)) and represents a reduced energy recovery. (C) 2002 Elsevier Science Ltd. All rights reserved.