Jun 15, 2019 - Energy & Environment

Solving the plastic problem

An employee walks through plastic wastes waiting to be recycled at a sorting center in France

A sorting center in France. Photo: Loic Venance/AFP/Getty Images

Plastics are intertwined with our lives today — driving researchers to create plant-based versions and more efficient ways to recycle.

The big picture: From a science perspective, the biggest challenge is consumers and companies want materials that won’t degrade quickly while being used but will degrade quickly once disposed, says Andrew Dove, a professor of chemistry at the University of Birmingham in the U.K. “The world wants it both ways.”

"It's an incredible material," says Marc Hillmyer, who directs the Center for Sustainable Polymers at the University of Minnesota, and points to plastics use in transporting food and water, and protecting solar cells and windmill blades that anchor the renewable energy economy.

  • "We need them, but not for everything," he says.

How it works: Plastics are recycled or burned as a source of energy, but by one estimate, 79% of plastic waste has ended up in landfills or the environment.

  • Plastics can be mixed with pigments, other materials and other plastics, which complicate recycling and limit how the chemical components of plastic can be reused.

The push for "green plastics" made from sustainable materials gave us, for example, cups made from corn-based plastic (polylactic acid) and compostable chip bags that degrade under certain circumstances.

  • Researchers are trying to develop new materials that could replace common plastics — from that foam in flower arrangements to straws.
  • The challenge is finding a sweet spot between making a plastic easier to break down and the need for durability and other desired characteristics.

Replacing petroleum-based plastics is still important in the long term, says Dove, but as it accumulates in landfills, researchers are increasingly focusing on new ways to make and recycle today's materials.

  • Lawrence Berkeley National Laboratory researchers recently reported a new way to create a plastic commonly found in epoxies and polyurethane.
  • They were then able to break it down to its chemical building blocks, even when the plastics were colored or with other materials, and turn them back into plastic.
  • Yes, but: The process requires large amounts of water and hasn't been demonstrated to work on an industrial scale.

Scientists are also experimenting with degrading plastics using:

  • Chemical recycling: Different acids and bases can be used to break down plastics. Researchers hope to develop chemicals that can selectively degrade a single type of plastic in a stream of mixed plastic waste.
  • Enzymes: They have the advantage of being specific to a type of plastic but the disadvantage of working slowly compared to chemical recycling.

The bottom line: It's going to take a combination of new materials and improved recycling methods to minimize the impacts of our plastics dependency. "There's not going to be a panacea," says Hillmyer.

Go deeper: Scientists grapple with the world's plastic problem

Go deeper