On a Wednesday afternoon in a sprawling lot on a former naval air station in Alameda, California, across the bay from San Francisco, workers are welding a massive black tube together. The tube–roughly the length of a football field–is one piece of a larger system that will set sail for the Great Pacific Garbage Patch this summer, where it will begin collecting some of the 1.8 trillion pieces of plastic trash brought there by ocean currents.

Six years ago, the technology was only an idea presented at a TEDx talk. Boyan Slat, the 18-year-old presenter, had learned that cleaning up the tiny particles of plastic in the ocean could take nearly 80,000 years. Because of the volume of plastic spread through the water, and because it is constantly moving with currents, trying to chase it with nets would be a losing proposition. Slat instead proposed using that movement as an advantage: With a barrier in the water, he argued, the swirling plastic could be collected much more quickly. Then it could be pulled out of the water and recycled.

Some scientists have been skeptical that the idea is feasible. But Slat, undeterred, dropped out of his first year of university to pursue the concept, and founded a nonprofit to create the technology, The Ocean Cleanup, in 2013. The organization raised $2.2 million in a crowdfunding campaign, and other investors, including Salesforce CEO Marc Benioff, brought in millions more to fund research and development. By the end of 2018, the nonprofit says it will bring back its first harvest of ocean plastic back from the North Pacific Gyre, along with concrete proof that the design works. The organization expects to bring 5,000 kilograms of plastic ashore per month with its first system. With a full fleet of systems deployed, it believes that it can collect half of the plastic trash in the Great Pacific Garbage Patch–around 40,000 metric tons–within five years.

The system uses a giant floating tube–the first one will be 2,000 feet long–made of a durable plastic called HDPE, which can float in the water, flexible enough to bend with the waves, but rigid enough to form a U-shaped barrier to stop the plastic floating on the ocean’s surface. A strong nylon screen, attached underneath, will catch some of plastic below the surface, but because it isn’t a net, won’t catch marine life. Large anchors, floating in still water hundreds of feet below the surface, will help steady the device so it moves in the current more slowly than the plastic, making it possible to scoop up the plastic that’s collected in front of the device.

There have been multiple engineering challenges along the way. The design originally called for an anchor attached to the seabed, but because of the expense and complication, the team had to abandon the plan; they eventually realized that a floating anchor could work. “There were many times in the last few years that were really rough,” Slat, now 23, told me as we sat on a pallet surrounded by sections of the device. The fact that there was so much at stake helped him keep going.

“I would never be able to work on a photo-sharing app or ‘internet startup XYZ,'” he says. “I think people overestimate the risk of high-risk projects. Personally, I think I would find it much harder to make a photo-sharing app a success–it sounds counterintuitive, because it’s much easier from an engineering perspective, but I think if you work on something that’s truly exciting and bold and complicated, then you will attract the kind of people that are really smart and talented. People that like solving complicated problems.”

In a few weeks, the first piece of the technology, the length of a football field, will be towed out of the San Francisco Bay, along the coast of the Farallon Islands, where the team will test how the system holds up to towing. To make it to the Pacific Garbage Patch, the equipment will need to be towed for three weeks. After the local “tow test,” the engineers will bring the first section back, and connect the rest to form a total of the 2,000 feet of piping, slightly longer than the Sears Tower is tall.