Microalgae viewed under a light microscope

It is heartening to see the research community continue the quest to find realistic alternatives to petroleum-based plastics. A group at the University of California San Diego (UCSD) continues building on previous work that developed algae-based flip flops and rigid foam used in surfboards. Their latest effort is purifying oil from green microalgae for use in manufacturing biodegradable forms of coated fabrics, patent leather, adhesives, and even food flavoring and fragrances.1

According to a press release from UCSD, “Many researches consider algae one of the best renewable resources for replacing fossil fuels and battling global warming without impacting food supplies. But unlike vegetable oils, the oil from algae contains small organic contaminants, like photosynthetic pigments and other cofactors that can complicate their use.” 1

Image from the UC San Diego research team’s prior work, showing a student pouring polyurethane into a flip-flop mold. Photo by Erik Jepsen/UC San Diego Publications


The UCSD team developed a method to purify oil leftover from processing Nannochloropsis salina, a green microalgae used to make omega-3 fatty acid dietary supplements. The oil is normally discarded by supplement manufacturers, but in the hands of the UCSD researchers, the oil is used as a building block for sustainable bio-based plastics.2

In an interview with one of the lead researchers, Prof. Michael Burkart said, “This study indicates that an algae-sourced waste stream has both the practical and economic potential to support material production of polyurethanes…We are already working with major shoe companies to turn these into commercial products that people will want to buy. We are finding that consumers are concerned about all of the petroleum-based plastic waste we are generating as a society, and our team is rapidly developing solutions for future products. Stay tuned!” 1

The video below shows another member of the UCSD team, Prof. Stephen Mayfield, discussing their laboratory’s earlier work to develop flip flops and surfboards from algae used as a substitute for petroleum in making both rigid and soft foams. He explains the important differences in their products over traditional petrochemical plastics is that “the carbon in this shoe was captured from the atmosphere, not pulled from underground” and at the end of the shoe’s useful life “you can throw this into a compost pile and it will be eaten by organisms.”3

Prof. Mayfield explained the reason they focused early efforts on flip flops: “Even though a flip flop seems like a minor product, a throwaway that everyone wears, it turns out that this is the No. 1 shoe in the world…These are the shoes of a fisherman and a farmer. This is the No. 1 shoe in India, the No. 1 shoe in China and the No. 1 shoe in Africa. And, in fact, one of the largest pollutants in the ocean is polyurethane from flip flops and other shoes that have been washed or thrown into rivers and flow into the ocean.”4

UC San Diego has a grant program aimed at helping researchers establish the usefulness of laboratory discoveries so that their work can move from the ivory tower to consumers. Mayfield’s team secured a grant in 2017 through the “Accelerating Innovations to Market” program to develop Triton soles. In early 2020, it was announced that the REEF footwear company will officially launch a line of flip flops using the algae-based material.5,6

We will continue following the team’s research and bring updates when available. Until then, we will be looking for a nice pair of algae flip flops!

—R.A. Kroft


1Dillon, Cynthia. Researchers Turn Algae Leftovers into Renewable Products with Flare. UC San Diego News Center. Press Release. 11 May 2020.

2Phung Haia, TA et al. Co-production of flexible polyurethanes and renewable solvent from a microalgae oil waste stream. Green Chemistry. Accepted Manuscript, 2020.

3Video: UC San Diego. “Algae Flip Flops.” 5 October 2017.

4McDonald, Kim. A Flip Flop Revolution. UC San Diego News Center. Press Release. 5 October 2017.

5Fitzpatrick, Lynsey. Campuswide Proof-of-Concept Awards Move Innovations to Market. UC San Diego News Center. Press Release. 26 April 2017.

6Algenesis. REEF X SoleicTM. Company News. 6 March 2020.

Cover Image: By Inks002 – Own work, Public Domain, Nannochloropsis sp. microalgae viewed under a light microscope. Photo taken at Wageningen University.

R.A. Kroft writes about her day-to-day journey in living a smaller, more sustainable life and other topics that interest her.

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