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Biohydrogen production from microalgal biomass: Energy requirement, CO2 emissions and scale-up scenarios

Ferreira, Ana F., Ortigueira, Joana, Alves, Luís, Gouveia, Luísa, Moura, Patrícia, Silva, Carla
Bioresource technology 2013 v.144 pp. 156-164
Clostridium butyricum, Scenedesmus obliquus, biohydrogen, biomass, culture media, emissions, energy, energy requirements, fermentation, fuel cells, hydrogen production, life cycle inventory, microalgae, ponds, production technology, raceways
This paper presents a life cycle inventory of biohydrogen production by Clostridium butyricum through the fermentation of the whole Scenedesmus obliquus biomass. The main purpose of this work was to determine the energy consumption and CO2 emissions during the production of hydrogen. This was accomplished through the fermentation of the microalgal biomass cultivated in an outdoor raceway pond and the preparation of the inoculum and culture media. The scale-up scenarios are discussed aiming for a potential application to a fuel cell hybrid taxi fleet.The H2 yield obtained was 7.3gH2/kg of S. obliquus dried biomass. The results show that the production of biohydrogen required 71–100MJ/MJH2 and emitted about 5–6kgCO2/MJH2. Other studies and production technologies were taken into account to discuss an eventual process scale-up. Increased production rates of microalgal biomass and biohydrogen are necessary for bioH2 to become competitive with conventional production pathways.