Biocombustibles

PHOTOBIOREACTOR TECHNOLOGY FOR MICROALGAE CULTIVATION
The cultivation of microalgae provides excellent perspectives for renewable energy production and as a source of ‘green’ products. Algaecultivation can thus contribute substantially to a reduction of CO2 emissions. Micro-algae are microscopic, single-celled plants, growing in aqueous environment. For growth algae make use of sunlight asenergy source and simple inorganic nutrients, predominantly CO2, soluble nitrogen components and phosphates. Characteristics of algae cultivation are: • The areal productivity is 2 to 5 fold higher ascompared with traditional agricultural crops and fast growing ‘energy crops’ such as willow and Miscanthus. • Lower quality water can be used for growing algae, e.g. the effluent of biological wastewater treatment facilities. Algae effectively remove nitrogen and phophate from these streams, which leads to a reduction of water treatment costs. After separation of the algae (and final conditioning)the purified water can be reused for industrial purposes. • Algal systems can remove CO2 (and NOx) from flue gases. The flue gases from power plants can be directed through the algal bioreactor. CO2 istaken up by the algae and directly recycled in the form of biomass and derived products. • Many algal species produce valuable products, such as colorants, polyunsaturated fatty acids and bioactivecompounds. These ‘fine chemicals’ are applicable as a natural ingredient in food products, pharmaceuticals, food supplements and personal care products. After extraction of these valuable compounds theremaining biomass (approx. 80%) can be used for production of ‘green’ electricity and heat. Alternatively, microalgae can be used for the production of methylesterfuel (‘bio-diesel’).

The ECNbench scale photobioreactor

Microalgae of the species Chlorella pyrenoidosa. The actual cell size is 3-5 mm (1 mm = 0.001 mm)

The high biomass yield, the possibilities for co-production of fine...