Episode 44: Solving the Plastic Crisis with Seaweed

Sway is making sustainable plastic alternatives to replace the single-use stuff that, at this point in the industrial economy, is almost impossible to get rid of.

This week on the pod, I’m super excited to talk with someone I’ve been trying to chase down for a while — Julia Marsh, the CEO and co-founder of Sway, a company using seaweed to create sustainable plastic alternatives.

As we have stipulated and will continue to hammer from now until we figure out how to solve this problem, the global plastic crisis is staggering — over 380 million tons of plastic are produced each year, much of it for single-use packaging that pollutes our environment. Plastic is incredibly useful, but it also comes with a huge environmental cost. Not only does plastic waste clog our oceans and landfills, but plastic is made out of fossil fuels, contributing to climate change.

In fact, research published just this week, out of Lawrence Berkeley National Laboratory, finds that plastic production emissions are on a path to triple by the middle of the century and will then account for fully a fifth of the world’s carbon budget. And it’s not because it’s energy-intensive to produce plastic. It’s because 70% of the emissions come from the raw materials—the oil and natural gas that we desperately need to leave in the ground.

Molly Wood and Julia Marsh of Sway, waxing rhapsodic about the magic of seaweed.

So, back to solutions. While some plastic waste can be avoided through better product design and more reusable systems, Julia told me there is a significant category of "unavoidable" plastics - flexible films like bags, wrappers, and pouches - that are incredibly difficult to replace. These plastics are cheap, lightweight, and effective, but they are also the least likely to be recycled, and end up as toxic, horrible, turtle-choking, people-poisoning pollution.

This is where Sway comes in. By using seaweed as a key material, the company has developed compostable, bio-based alternatives that can plug directly into existing plastic manufacturing infrastructure. Seaweed is an abundant, fast-growing resource that can be cultivated in a restorative way, sequestering carbon and supporting marine ecosystems. And, crucially, Sway’s seaweed alternatives can be manufactured using the same methods that we currently use to produce plastic.

There are other bio-based plastic alternatives out there, like PLA made from corn, thermoplastic starch derived from cassava or potatoes, and even wood-based bioplastics. The challenge is ensuring these materials are truly sustainable and compostable, not just "greenwashed" versions of traditional plastics — I put Julia through a bit of a lightning round about what you can look for on labels to try to make sure you’re shopping as best you can.

You can learn more about Sway and hear the full interview with Julia Marsh on the Everybody in the Pool podcast. See you on the seaweed world tour!