Growing Microalgae For Biodiesel
Running on Algae by Celeste Yates
A paper by CSIR researchers, Dheepak Maharajh and Asha Harilal named ‘Transforming South Africa’s Biodiversity into Diesel’ has taken us one step closer to a future where we could be running on algae.
The paper presented the isolation of beneficial organisms and the best organisms from that potential in the biomass process. Currently biodiesel production and research are focused on crop based feedstock, such as palm oil. Researchers and stakeholders in the field are concerned that these biomass products could become unsustainable in the long term due to arable land and water requirements – not to mention the competition with food crops.
Algae has shown great potential in being the possible solution, as 40% can be harvested as fuel according to Maharajh;
“Algae generally grow at lower densities than bacteria or yeast, but their growth rates are far superior to terrestrial plants. These masses are specific to the organisms capability to produce oil. Eg, to produce 1 litre of fuel from an algae that produced 40% oil we would require 2.5kg of dry algal biomass, which could be as much as 2500L of liquid culture”
Microalgae have an oil yield at least 10 times better than oil seed crops and are capable of using environmental waste substrates such as carbon dioxide and nitrate-rich waste water for growth. For the last three years CSIR researchers have been actively sampling South Africa’s biodiversity and have successfully obtained over 200 isolates. When asked how algae biomass compares to palm oil Maharajh responded:
“For Biodiesel production the vegetable oil feedstock should contain a certain profile for fatty acids to be comparable to fossil diesel. Algae produce a wide range of the fatty acids and through process interventions we can make the organisms produce the fatty acid profile we require. However in general the oil produced by algae has a lower free fatty acid composition than palm oil for example. Free fatty acids are bad for the biodiesel production process and therefore the answer to your question is that it is comparable and sometimes better.”
Certain criteria must be reached for successful mass culture of algae. The selected algal strain must be a local strain with a rapid growth rate and must have high photosynthetic efficiency and light-harvesting capabilities to name a few. South Africa is an ideal place to do research due to the richness of South Africa’s biodiversity and the countries moderate climate and availability of sunlight.
However, the paper also reveals that not all isolates are capable of growth on solid media. Some grow synergistically on liquid medium and cannot be separated by traditional means. Out of the samplings in the paper, four isolates show promise and need future studies. Maharajh told us that in the future, there is a possibility that fuel could be created rather in the lab than with oil drills;
“The envisaged process from algal biodiesel production is intricate and contains many process steps, however a similar number of processes are currently used for fossil fuel production, albeit at a more developed level. Once the process for algal fuel production is developed the system will run smoothly and if economics are feasible it will be feasible for companies to take up this route.”
Once algae have been selected as potential fuel producers, the cells can be produced in the lab and there will no further disturbance to the environment is necessary.
About the Author
Celeste writes for South African biodiversity, a media company focusing on conservation and the environment.
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