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.