Many researchers consider algae to be one of the best renewable resources for replacing fossil fuels and even as a food source. The green microalgae Nannochloropsis salina is already a common source of omega-3 fatty acids that are sold as dietary supplements. As a result, that algae strain is already grown on a large scale for the production of omega-3 products.
A group of researchers at UC San Diego has developed a way to make use of the waste stream from that production to create plastics and other useful products. Currently, when the algae is processed to extract the omega-3 oil, leftover oils comprising more than 70% of the starting material are either thrown away or burned.
The UCSD team has developed a process to purify and convert this waste stream into azelaic acid, which is a building block for flexible polyurethanes. These materials have all kinds of commercial applications from flip-flops and running shoe soles to mattresses and yoga mats.
By analogy to the use of animals by native American tribes, the researchers wanted to “use the whole buffalo” in their solution for algae processing waste and therefore figured out how to convert heptanoic acid – another substance in the algae waste stream – into a food flavoring and fragrance. The flavoring molecule is valued at over $500 per kilogram.
The work, published in the journal Green Chemistry, demonstrates that an algae-source waste stream has both the practical and economic potential to support production of polyurethanes. The team is already working with shoe companies to commercialize the technology. With mounting concern over petroleum-based plastic waste, renewable plastic made from algae is an attractive alternative.
Photo, posted November 8, 2006, courtesy of Adam Moore via Flickr.