The Ocean Cleanup vessel is on its way to clean up the Great Pacific Garbage Patch

On September 8, a ship towing a 2,000-foot-long floating tube will leave a shipyard in Alameda, California, and slowly move under the Bay Bridge, past Alcatraz, under the Golden Gate Bridge, and into the Pacific Ocean. A few weeks and 1,000 nautical miles later, it will arrive at the Great Pacific Garbage Patch–the gyre where an estimated 1.8 trillion pieces of plastic float in the water–and begin the first experiment to clean it up.

It’s a massive challenge. The so-called Garbage Patch, filled with a plastic soup of discarded fishing nets and fragments of old water bottles and bags, is twice the size of Texas. Though plastic is found throughout the ocean, swirling currents make concentrations higher in the area; a recent study suggests that there is 16 times more plastic in the patch than researchers previously believed. Some of the pieces of microplastic are too tiny to collect. And nothing like the new experiment, called The Ocean Cleanup, has ever been attempted.

“Ocean plastics are a legacy problem with no easy solution,” says Lonneke Holierhoek, COO of The Ocean Cleanup. “Without taking action, however, we are sure that the problem will only get worse.”

The concept for the project began six years ago, when 18-year-old Boyan Slat, at the time a student, learned about the difficulty of removing plastic from the ocean. Because plastic is everywhere and the pieces continually move with currents, it isn’t possible to simply scoop it out with a net. Slat proposed using a barrier, instead, to gather plastic in one place, similar to the way that floating trash tends to collect at shorelines.

The idea, first presented in a TEDx talk, gathered enough traction that Slat dropped out of his university in 2013 to launch a nonprofit to produce it. He raised $2.2 million in a crowdfunding campaign and millions more from investors. After multiple iterations of the design, the latest version uses a giant floating tube made of HDPE plastic, the same type of tube that is used in fish farming in open water. Shorter pieces are welded into the full 2,000-foot structure, longer than the height of a 100-story building. Along the length of the tube, a three-meter-high nylon screen is designed to catch plastic.

As the tube floats in the water, wind and waves will push it slightly faster than the currents moving below. The plastic underwater, moving at a slower speed, will accumulate next to the screen. The shape of the screen–slightly longer in the middle–will make the tube curve into U-shape, which also helps the device catch more plastic. Every few months, a boat can come to the area and a team can remove the plastic, bringing it back to land to be recycled.

The new test will prove how well the system works. One challenge is whether it will survive ocean storms. The nonprofit’s team of engineers, with experience in constructing offshore oil platforms and wind farms, chose a material that should be both durable and flexible enough to move with waves and survive load forces that have a probability of happening once in 100 years. They tested scale models in labs, ran computer models, and tested components in the North Sea. But only after the full system has spent the winter in the middle of the ocean will they know exactly how it performs.

“We haven’t been able to test the full system in its natural environment in the ocean to actually confirm that it behaves as we discovered during all of the model testing and all of the computer testing that we’ve done,” says Holierhoek.

The tests so far, however, have been promising. In May, the team brought a piece of the system the length of a football field into the Pacific off the coast of Northern California. “It basically went straight into quite a nice storm,” says Holierhoek. In turbulent, steep waves–a good sample of the extreme conditions that the team expects to occur in the Garbage Patch–the system moved well. “We were able to confirm that the system behaves as we would expect and would like to see it behaving.”

When the system is towed out of the San Francisco Bay on September 8, it will be installed in its full U-shape for the first time and monitored for another two weeks. At the Garbage Patch, the new tests will also show if the system collects and keeps plastic trash as well as scale models and computer models have suggested. Though some tiny fragments of plastic may be too small to capture, the team worked with researchers to determine that most of the plastic floating near the surface is still in larger pieces. That makes it more critical to capture now. “Once it’s broken down and in really, really minute pieces, it becomes really hard to take it out, and it’s far easier for it to end up in the food chain,” says Holierhoek.

The beta system will be tested over the next year, with team members living on a vessel next to it to monitor performance. A protected species observer will study any impacts on marine organisms (because the system moves slowly, creatures should be able to swim under and around it, and the “skirt” under the tube is impenetrable, so it can’t trap animals like a net would). Marine biologists will study how much the structure attracts fish–fishermen use similar structures in the ocean–which may become a problem if it tempts commercial fishing to begin in the area. Biologists on board will also study the broad impact of ocean plastic.

Within a few months, the Ocean Cleanup expects to bring its first harvest of plastic back to San Francisco, where it will work on the next challenge–how to turn a mix of dirty, sometimes smelly plastic into a material that can be used for new products. There are companies that want to use it. Brands have already experimented with using ocean trash; one early prototype, from Adidas, used old fishing nets to knit a sneaker. (Fishing nets, it turns out, make up a large portion of the trash in the Great Pacific Garbage Patch.) While companies working with “ocean plastic” have often focused on using plastic collected from beaches, the Ocean Cleanup will have to find a way to work with much more challenging material that has been disintegrating in the water for months or years.

“It’s very contrary to what’s normal in the recycling industry, where recyclers use large volumes of very predictable and very constant material and they recycle it to generally downgrade from what it was originally,” says Holierhoek. “We are trying to recycle discarded packaging into high-end consumer products.”

As the first system is proven, the organization will also work on the next iteration of the design, set to launch in 2019.”After a year of operation we will have the information that we so desperately want, and feed that back into a redesign phase,” she says. “We do expect that the next generation of the Cleanup system needs to be even bigger and better and smarter.” Once the next version exists, the team plans to build and launch 60 of the systems–a full fleet that within five years, they say, can collect half of the 80,000 metric tons of plastic in the area now.

If the system works, it’s only part of the solution. “I am concerned that the general public can look at a project like this and see it as a panacea for the plastic pollution problem,” says Eben Schwartz, who manages the Marine Debris Program for the California Coastal Commission. “The fact is there is no one solution to this problem.” While there is around 540 million pounds of plastic in the ocean’s five gyres, Schwartz says, another 18 billion pounds of plastic enters the ocean every year. Stopping that flow of trash, by redesigning products and infrastructure and changing behavior, also needs to happen.

The solutions aren’t mutually exclusive, and arguably need to happen simultaneously. “It’s clear to everybody that we need to stop increasing the abundance of plastic debris that is [going] in the ocean, but it’s also clear that we already have a lot in it, and that it is going to take a long time for that debris to get out of the system even if we stopped producing at all,” says David Die, a professor in the University of Miami’s Department of Marine Ecosystem and Society who is working with the Ocean Cleanup to research effects of the project on fish. “Let’s hope that the Ocean Cleanup people have gotten into something that is a really effective solution. It seems like from the work that’s done in the lab and in some of the pilot projects that there is some real hope that this will work.”