Algae cultivated to produce bioenergy can be a very efficient way of fabricating raw material for fuel and bioenergy in general. However the industry is still in its infancy and extensive further research and development of both algae cultivation techniques as well as oil extraction methods from algae are required. It will take at least several more years before algae oil will be produced in large quantities at competitive prices compared to equivalent vegetable oils. And even more important, if algae will be used for energy or fuel purposes, the energy used to cultivate the algae and produce the biomass and biofuels shall need to be significantly less than the energy generated by the algae products. In short, the net energy value for algae products needs to be significantly positive both from an economic perspective but foremost for the environment for algae to be a sustainable renewable energy source
Algae can be described as a relatively simple organism living in water that captures light energy through photosynthesis and uses it to generate organic matter out of inorganic substances.
There are several methods to harvest the algae. By centrifuging or flocculation. Another new method still in research is harvesting algae using ultrasound. After harvesting the oil can be extracted by means of chemical solvents or expeller press which are very similar processes used to extract oil from oilseeds such as Jatropha or Castor seeds.
The oil yield promise of algae are spectacular. The figures of course depend on the algae strain used and local conditions. For biodiesel production it is necessary to cultivate algae with a high lipid content. Although there are little officially confirmed figures, yields have been recorded between 11 up to 93 MT/ha in laboratories in optimal conditions. That is almost up to 20 times more than the oil palm which currently gives the highest oil output per ha. It is however imperative to be connected or near to a carbon dioxide source such as power plants, breweries, cement factories or coal plants.
The advantages of algae based biodiesel supply chains are numerous but to mention a few:
The need for land is substantially lower and it does not have to be farmland. Algae production does not pose a threat to feedstock production and will therefore not have undesirable effects on the prices for food.
As a result of the far more efficient oil production of algaes, it becomes much more viable that biofuels can be an alternative to replace a large volume of fossil fuel.
Algae use carbon dioxide to convert inorganic substances into oil, which counter effects global warming and is therefore considered environmentally climate neutral, and is financially interesting for investors thanks to the eligibility for carbon credits. (emission trading)
Algae oil has favourable characteristics for biodiesel fabrication and can also be transformed into A1 jetfuel replacing fossil kersone. The aviation industry has already performed test flights on algae oil blends.
Sources: Round, F.E. 1981. The Ecology of Algae. Cambridge University Press, London. ISBN 0 521 22583 3 Mumford, T.F. and Miura, A (1988). "Porphyra as food: cultivation and economics". In Lembi, C.A. and Waaland, J.R. (Ed.) Algae and Human Affairs: 87-117. Biodiesel Production from Algae. Department of Energy Aquatic Species Program, National Renewable Energy Laboratory.
Algae