September 2018 was an exciting time for “Ocean Cleanup”, an ambitious project aiming to remove floating plastic from the Great Pacific Garbage Patch, an infamous gyre of floating plastic waste collected by currents in the East Pacific Ocean. The project aims to collect floating plastic materials by mimicking longshore currents that transport debris along natural shorelines.
After several years of testing, the first full-scale Ocean Clean up vessel, dubbed ‘System 001’, was towed out to sea from San Francisco Bay on September 8, 2018. The vessel consists of a 600 m (2,000 foot) long free floating boom. Its appearance is like that of the familiar plastic booms used to contain oil spills across the world. However, it has several key distinctions.
When deployed, the boom is shaped into an open ended ‘U’. Under the surface of the water is a hanging sieve-like net, designed to catch plastic particles and larger pieces of debris and shepherd them along the boom towards the centre of the U. The sieve extends deeply at the centre of the boom, and less deeply at the edge. This allows the current to push the centre more quickly, causing the boom to take on its characteristic ‘U’ shape.
Early versions of the design called for an actual collector device at the centre of the boom – essentially a cage that the plastic would be forced inside of. However, testing and research suggested that it would be more effective for the plastic to simply become concentrated within the U. Once the plastic is concentrated, a ship will approach the boom and collect the plastic with a smaller boom. It will then deliver the plastic to shore where it can be recycled or buried.
Dutch inventor Boyan Slat, the founder of the Ocean Clean up project, is confident that System 001 will be the first of a flotilla of 60 similar devices.
The project is not without critics. Some worry that the system will be a danger to marine life, or that it will be a hazard to shipping. Ocean Clean up claims to have taken these risks into account, adding GPS-based location trackers and warning lights and redesigning the final collection procedure. Environmentalists also worry that the project is distracting from critical efforts to stop plastic from entering the ocean in the first place.
Slat takes a more pragmatic approach to this issue. This Science Magazine article quotes him as follows: “We need to do both. We need to intercept plastic before it becomes ocean plastic. And we need to clean up what is out there.”
Whether the project will result in a cleaner ocean should become clearer once the first test run is done in late October.