Ocean Cleanup sets sail to Great Pacific Garbage Patch

In a launch seen globally through an internet livestream, a tugboat departed San Francisco Bay on Sept. 8 bound for the Great Pacific Garbage Patch with a marine litter collection system in tow, designed to rid the seas of plastic.

Deployed by the Rotterdam, Netherlands-based nonprofit group Ocean Cleanup, the 2,000-foot-long system consists of a floating plastic boom with a tapered plastic screen extending 10 feet underwater. The plan is to capture plastic debris at or near the surface for eventual recycling.

The launch, which had 452,000 views online, was the culmination of five years of ocean plastic research, prototyping and fundraising. The project attracted about $35 million in donations and sponsors like PayPal co-founder Peter Thiel.

Building upon lessons learned from offshore oil and gas producers, the Ocean Cleanup team worked with the staff of Agru GmbH and its Georgetown, S.C.-based Agru America Inc. subsidiary to develop a boom made of buoyant and flexible high density polyethylene pipe that can withstand the harsh conditions of the Pacific Ocean. As the boom floats on the waves, it should keep garbage from flowing over it. Meanwhile, the drag on the polyester woven skirt should give the system a U-shape that collects plastic like a Pac-Man gobbling dots.

Both the marine litter and unmanned removal system will be carried around by the currents, but only the plastic pipe-and-screen components will be propelled by the waves and wind. That should enable the system to move faster than the gyre garbage and capture it.

"This is something we've been able to study a lot with scale models, with computer simulations, but I'll still be very relieved when we are able to see this in reality," 24-year-old Ocean Cleanup CEO Boyan Slat said in a Facebook video ahead of the launch.

Slat expects to find out how the collection system behaves in the ocean at a test site on the way to the patch. He is most anxious about how it interacts with plastic.

"It's very hard to scale plastic," Slat said. "You have things like surface tension, which will influence your results. It's something we can only truly find out when we deploy a full-scale system in the Great Pacific Garbage Patch."

Some 1.8 trillion pieces of plastic fill the patch between California and Hawaii. That's about 250 plastic bits, caps, shards, toys and ghost nets for every human, according to mid-range estimates of the Ocean Cleanup.

The first removal system — dubbed System 001 — will be tested for a couple weeks about 300 nautical miles offshore before going another 1,000 nautical miles to the largest of the five places where ocean currents concentrate plastics. At speeds of 2-4 knots, the system should reach its destination in mid-October.

In the patch, System 001 is expected to gather up to 150,000 pounds of plastic in its first year. If more booms are deployed, the Ocean Cleanup says half the patch could be cleaned in five years.

The group plans to collect the concentrated ocean plastic every few weeks and deliver it to what has been described as a waste-carrying mother ship, which will then take it ashore for recycling.

"If the first Ocean Cleanup system is successful, a full fleet of 60 floating screens will be launched over time in the Great Pacific Garbage Patch," according to a Sept. 10 news release from Agru America.

Future booms reportedly will cost about $5.8 million each. If enough are placed in the gyres, and land sources are reduced as well, a plastic-free ocean by 2050 is possible, Slat's group says.

Boom time

System 001 is made with HDPE pipe produced by Agru in Austria.

"The Agru XXL piping system is the backbone of the 2,000-foot-long floating construction, which will form an artificial coastline in the ocean where plastics waste is intended to accumulate," the company says.

The floater pipe was developed by both Agru and Ocean Cleanup. Agru custom made it with high grade PE 100-RC resin.

"Although no internal pressure is created in this application, the external stresses caused by the waves, UV radiation, storms and aggressive salt water are enormous, and would push any other material beyond it limits," Agru said.

The system's flexibility will allow it to survive one of the most rugged places on the planet, the company adds.

"In order to ensure maximum buoyancy even in the event of damage, the floater needs to be split into a number of hollow compartments like a ship. Agru produced the bulkhead partition walls to form these air-tight compartments, and took care of welding them into the pipes with the highest degree of precision," Agru said.

Other considerations

Ocean Cleanup designed the rail system to secure the skirt to the floater, and Agru installed it. For the dove tail joint, Agru machined sheets of PE 100-RC and welded it to the floater. The company also supplied ballast pontoons made of PE 100-RC pipe to stabilise the floater and top load spigot saddles to act as attachment points for lights to give position, satellite antennas to communicate location, and bollards for the ships that visit to inspect the system and collect garbage.

"The complete system was prepared for use under the guidance of Agru experts in San Francisco," the company said.

Agru America is part of Alois Gruber GmbH, an Austrian family-owned business that was has production facilities in Austria, the United States, Germany, China and India and distribution centers in more than 80 countries. Founded in 1948, the company produces lining systems and pipe and fitting systems for civil, energy, environmental, mining, water and wastewater applications.

While not naming Agru in the Facebook video, Slat acknowledged his group benefited from the industry's professionals.

"I have a lot of faith in the engineers that have spent 10s of years in the off-shore oil and gas industry designing these massive structures that have survived for a very long period of time," Slat said in the video.

He also gave a small nod to plastic's durability and humanity's ingenuity as he talked about the high winds, strong currents, UV light, corrosive salt and "nibbling" marine animals that the Ocean Cleanup system will face.

"Having something in the ocean, man-made that's able to survive for long periods of time — that's really quite an achievement," Slat said.

He hopes simplicity is on the project's side.

"There's not a lot of things that can break," Slat said. "But still I will be very happy if the system goes through the first winter without any significant damage."