Deploying Plastic Against Itself

The amount of plastic debris in the oceans now amounts to hundreds of millions of tons, much of it concentrated in gyres or patches each the size of a largish US state. Although it doesn’t really go away, plastic does break down into smaller pieces—microplastics—that are easily ingested by birds and marine life, either killing them or working its way up the food chain.

Until now, most efforts to solve the problem have focused on reducing the use of plastics, recycling them more effectively, and keeping them out of stormwater runoff and therefore out of the rivers, lakes, and oceans. Cleaning up what’s already out there would be prohibitively expensive, almost everyone agrees. Sending out a fleet of vessels with nets would be an almost futile gesture, given the size of the problem, and the nets would be as likely to trap fish and other marine life as they would be to capture debris. Now, though, a nonprofit group called Ocean Cleanup has proposed a new plan—deploying a passive system made largely of (what else?) plastic to capture the larger pieces before they can break down into smaller ones. The group optimistically believes that the system could reduce the Great Pacific Garbage Patch—that’s the one that’s about the size of Texas—by half within five years.

You can see a detailed description of the system here, but basically it consists of a series of semi-rigid, U-shaped “floaters” made of high-density polyethylene. Each will be up to 2 kilometers long, and suspended from the bottom of each one will be a solid screen and then a flexible, drifting barrier, weighted at the bottom—something like a movable turbidity curtain—which will capture the debris. Although the barriers, made of reinforced thermoplastic polyurethane, will be able to capture bits of plastic as small as a centimeter, fish should be able to swim under or around them.

Solar-powered sensors will record the condition and fullness of the systems, and vessels will meet up with them periodically to empty them and move the collected debris to shore, where it can be disposed of or recycled. A prototype system has been deployed in the North Sea off the coast of the Netherlands. The group hopes to deploy another system in the North Pacific later this year, and to begin tackling the Great Pacific Garbage Patch in 2018.