After another technical tweak, the Ocean Cleanup's marine sweeper is doing its intended job in the Pacific Ocean and collecting garbage from the size of large ghost nets down to microplastics as small as 1 millimeter, according to the Dutch nonprofit group.
The Rotterdam, Netherlands-based Ocean Cleanup announced Oct. 1 that it has successfully tested its redesigned plastic pipe-and-skirt system to act as a floating collection point for waste in the Great Pacific Garbage Patch, which is an accumulation zone for trash halfway between California and Hawaii.
The group says its self-contained system, which consists of a high density polyethylene floater pipe and a detached polyester screen to capture plastic debris to a depth of 10 feet, uses the natural forces of the ocean to passively catch and hold plastic. Ocean Cleanup CEO and founder Boyan Slat said the successful tests confirm the concept he first presented as an 18-year-old at a TEDx conference in October 2012.
"We're now catching plastics," Slat said at an Oct. 1 news conference.
The last year of testing in the harsh ocean "strongly indicates that our vision is attainable and that the beginning of our mission to rid the ocean of plastic garbage, which has accumulated for decades, is within our sights," Slat said.
To reach this point, Ocean Cleanup engineers had to overcome two main hurdles related to the inconsistent speeds at which the prototype moved in the water, followed by its inability to contain "prominent" plastic.
The engineers corrected the inconsistent speed of the system by attaching a parachute sea anchor to the 525-foot, U-shaped contraption. The parachute anchor slowed the system so it could catch plastic and concentrate it against the screen like a giant ocean rake.
However, some plastic debris still crossed the screen, which is held in place by a cork line, and it was getting caught in the space between the polyester skirt and the pipe. The group solved the "overtopping" problem by increasing the size of the cork line. The system is now capturing and concentrating plastic for eventual removal with the overtopping issue "nearly" eliminated, Slat said.
In the original cleanup system, the screen was attached to the floater pipe, but a section broke off when a stress crack formed at a welding point after only two months in the harsh ocean environment.
Now the Ocean Cleanup will begin to design a full-scale cleanup system to retain plastic for eventual removal and recycling. The timing of this phase of their mission depends on further testing and "design iteration," according to the group.
"This now gives us confidence of the general concept and to keep going on this path," Slat said, adding that the group is ready to initiate the System 002 project. "But if the journey to this point tells us anything, it's that it definitely won't be easy."
Before the operation is scaled up, the group needs to look at the long-term durability of the system, which will be exposed to years on the high seas, as well as the long-term retention of the plastic, which won't be collected for up to a year.
The Ocean Cleanup's mission is to passively rid the world's oceans of plastic by deploying a fleet of unmanned floating pipe-and-skirt systems to concentrate garbage for support vessels to collect every few months. The plan is to haul the marine debris from the patch, which is often compared in size to Texas, back to land for recycling.
"We're pleased to say we now use the natural ocean forces to capture plastic," Reijnder de Feijter, a hydrodynamic engineer for the group, said at the news conference. "This thing is ocean powered. It does it all by itself, and that from an engineering point, is a big success. We're very confident moving forward toward a full fleet of cleanup systems, hopefully as soon as possible."
The group says its calculations show a full-scale operation with 60 pipe-and-skirt systems that are 2,000 feet long could clean up 50 percent of the Great North Pacific Patch about five years from deployment.
Slat said the Ocean Cleanup is financially comfortable at the moment but will need more money to scale up. The group reportedly has raised $40 million from online donations, charitable groups, the Dutch government, and individuals, including PayPal co-founder Peter Thiel.
However, the Ocean Cleanup is facing steep operating costs. For example, Slat said the group's lone vessel in the patch costs 15,000 to 20,000 euros a day.
"The key to make the economics work is to have a system that can autonomously collect and concentrate the plastic for long periods of time," Slat said. "That's the jump we want to make from System 001 to System 002 — to upscale the system and for it to stay out there for maybe even a year so that theoretically you only periodically have to go out there and harvest the plastic."
To control operating costs, the economic metric to optimize is the number of vessel hours or days needed for every ton of plastic collected, Slat added.
The group founder said he could not share many details about how the plastic will be recycled and utilized when the first haul is returned to shore in December.
"The plan is actually going to be to go all the way to the supporters — the B2C [business-to-customer] — because we think the material value is actually really low," Slat said. "Of course it's much more expensive to get plastic from the middle of the ocean than from the garbage bin industry, so we do need to utilize the story value — the fact that it's coming from the patch and the value that you can actually help clean the ocean by purchasing products made from this material. That's really important. We will likely vertically integrate that aspect and go really far into the chain as we think that's where the most value to the material is added."
In a few years, when the full fleet of marine sweepers is deployed, the Ocean Cleanup plans to operate with money generated from the sale of the harvested plastic, Slat said.
"I do think we have the model to potentially cover the operational cost of the fleet," he said.