Graduate student P.Duan holds a vial of biooil. (Photo: Nicole Casal Moore)
Researchers work toward cheaper algal biodiesel
Friday, September 03, 2010, 03:40 (GMT + 9)
Scientists at the University of Michigan have been working on a two-step hydrolysis-solvolysis technique for algal biodiesel production directly from wet algal biomass while eradicating the need for the expensive processes of biomass drying, organic solvent extraction and catalysts. The paper was published in the ACS journal Energy & Fuels.
In the first step, wet algal biomass was made up of 80 per cent moisture and was reacted with subcritical water to hydrolyse intracellular lipids,
conglomerate cells into an easily filterable solid that kept the lipids and generated a sterile, nutritious and aqueous phase. In the second step, the wet and fatty acid rich solids went through a supercritical transesterification with ethanol to make fatty acid ethyl esters (FAEEs).
|Researchers heat algae in a device that acts like a pressure cooker to turn the algae into a crude biooil. (Photo: Nicole Casal Moore, University of Michigan)
The researchers used Chlorella vulgaris algae, which has a content of 53.3 per cent lipids.
Lead researcher on the project Phillip Savage told that the team collected the wet algae grown from the lab and centrifuged it to turn the algal biomass into a compound that resembles a paste, reports Biodiesel Magazine.
“At large scale that probably wouldn’t be applicable for an economical process,” he said. “We got something that was probably around 10 to 20 per cent solids to the balance of water.”
Although the research has given hopeful results, the project is expected to be improved and optimised so it can show superior economic and environmental viability of the process on a larger scale, Savage noted.
“More remains to be understood regarding how whole cells, hydrothermally processed algal biomass and intracellular constituents influence supercritical transesterification and potentially contribute to nonester components in the final fuel product,” the paper said.
“Additional research and process optimization are likely to improve yields and reduce process inputs (e.g., ethanol), thereby minimizing the overall environmental impact of algal biodiesel production. To be economically viable, biodiesel yields must be above 95 per cent and preferably higher than current norms achieved with alkali-catalyzed processes,” it concluded.
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By Natalia Real