Flip-flops are the world’s most popular shoe — but they also represent a large percentage of the plastic waste that ends up in landfills, on seashores, and in the oceans. But now there might be a better alternative, as researchers have come up with biodegradable flip-flops entirely made from algae.

Researchers from the University of California San Diego have developed polymer foams from algae oil that meet commercial specifications for midsole shoes and the foot-bed of flip-flops. They are sustainable, consumer-ready, and biodegradable materials that will eventually reach the shops.

“The paper shows that we have commercial-quality foams that biodegrade in the natural environment,” said Stephen Mayfield, co-author, in a press release.

“After hundreds of formulations, we finally achieved one that met commercial specifications. These foams are 52% biocontent, eventually we’ll get to 100%.”

The study was carried out in partnership with the startup company Algenesis Materials. They helped determine the right formulation for the commercial-quality foams and also to define the best way to make them biodegradable.

To do so, the researchers immersed the foams in traditional compost and soil, discovering it took 16 weeks for the materials to degrade. During that period, they measured the molecules shed from the materials to account for any toxicity. They also identified the organisms that degraded such foams.

“We took the enzymes from the organisms degrading the foams and showed that we could use them to depolymerize these polyurethane products, and then identified the intermediate steps that take place in the process,” said Mayfield.

“We then showed that we could isolate the depolymerized products and use those to synthesize new polyurethane monomers.”

This opens to the door to not just more eco-friendly flip-flops, but a new type of plastic product that is fully recyclable, the researchers argued. Plastic pollution in the oceans is expected to triple by 2040, according to a recent study by the NGO International Solid Waste Association, calling for action from governments and companies.

The researchers hope that the sustainable footwear, which is due to be launched through a major flip-flop brand next year, will cut the amount of plastic ending up in oceans and landfill sites. They estimated that over one billion flip-flops are made every year, accounting for major plastic pollution.

The challenge ahead will be the economics behind the production, which is something the team is trying to figure out with the manufacturing partners.

“People are coming around on plastic ocean pollution and starting to demand products that can address what has become an environmental disaster,” said Tom Cooke, president of Algenesis, in a press release.

The study was published in the journal Bioresource Technology Report.