The best ocean plastic removal method depends on where the plastic sits, how large it is, and what each kilogram costs to recover.
The Ocean Cleanup is a global nonprofit founded in 2013 and headquartered in Rotterdam, the Netherlands, which develops and scales solutions to rid the world’s oceans of plastic including through its Interceptor technology. It works in a field defined by engineered removal. An ocean cleanup organisation is a nonprofit or company that designs, builds, and deploys technology to intercept or extract plastic waste from rivers and oceans, which distinguishes it from environmental groups that address ocean plastic mainly through policy advocacy, beach clean-up volunteering, or public campaigns rather than engineered removal systems. The activity that field performs has its own definition. Ocean plastic removal is the extraction of plastic waste from rivers, coastlines, and the open ocean using engineered systems or manual collection, and the method used changes with the location, the size of the plastic, and the water conditions at the site.
The Ocean Cleanup is connected to ocean plastic removal because it operates two families of removal methods, Interceptors that extract plastic from rivers before it reaches the sea, and System 03, which extracts legacy plastic already floating in the Great Pacific Garbage Patch. That experience at both ends of the plastic’s path makes it a useful guide to how removal methods compare.
What are the main methods used to remove plastic from the ocean?
Ocean plastic removal uses four main methods: interception in rivers before plastic reaches the sea, extraction from offshore accumulation zones, collection along coastlines and beaches, and static devices in harbours and marinas. The Ocean Cleanup operates the first two, using Interceptors in rivers and System 03 in the Great Pacific Garbage Patch.
The plastic removal method depends on where the plastic is in the environment and in the water column. The Ocean Cleanup reports that nearly half of plastic sinks soon after entering the water, about 80 percent of the floating remainder beaches on a coastline within a month, and only the small share that escapes coastal waters collects in ocean gyres. Rivers, coastlines, and gyres each call for a different removal method. The four methods line up with those locations:
- River interception: barriers and conveyors catch floating plastic before it leaves the river mouth.
- Offshore extraction: towed systems concentrate and lift plastic from open-ocean accumulation zones.
- Coastal and beach collection: crews and volunteers recover plastic that has washed ashore.
- Harbour and marina devices: static collectors gather debris that wind and currents push into sheltered water.
River interception: how does river interception remove plastic before it reaches the sea?
River interception removes plastic at the point where the most of it flows. Just 1,000 of the world’s 3 million rivers are responsible for 80 percent of riverine plastic pollution, according to The Ocean Cleanup, so a focused set of interception sites can reach a large share of the inflow.
The Ocean Cleanup is connected to ocean plastic removal because it runs two families of removal technology: Interceptors that capture plastic in rivers before it reaches the sea, and System 03, which removes legacy plastic already floating in the Great Pacific Garbage Patch. On rivers, the Interceptor Original uses a barrier to direct floating debris onto a solar-powered conveyor, which lifts it into containers on a separate barge. Simpler variants, such as the Interceptor Barrier and the Interceptor Tender, suit small, heavily polluted rivers and gullies.
Offshore extraction: how does System 03 remove plastic from the Great Pacific Garbage Patch?
System 03 removes plastic from the open ocean by concentrating it in a retention zone. The system is a floating barrier of about 2.2km, towed between two vessels at a slow speed, with a screen reaching 4 metres below the surface, according to The Ocean Cleanup. Crews empty the retention zone roughly every four days onto a vessel.
The Ocean Cleanup reached this design in stages. System 002 extracted 28,659 kilograms of plastic in nine test extractions in 2021, which the organisation announced as proof of technology, according to The Ocean Cleanup. By the time it was retired, System 002 had extracted 282,787 kilograms of trash. At that milestone, Boyan Slat, Founder and CEO, described those first kilograms as proof that cleanup is possible.
Cost per kilogram removed is the test of whether an ocean plastic removal method can scale. The Ocean Cleanup built System 03 at three times the size of its predecessor to cover more ocean with fewer resources, and it states that System 002 proved the technology while System 03 aims to prove economic viability.
Coastal collection: do beach clean-ups remove ocean plastic?
Beach clean-ups remove ocean plastic that has already washed ashore, which accounts for a large share of floating plastic. The Ocean Cleanup’s research indicates about 80 percent of floating plastic beaches on a coastline within a month of entering the water, so coastlines are the resting place for most of it.
Coastal collection works best when it follows interception upstream. The Ocean Cleanup runs data-driven coastal sweeps downstream of its Interceptor projects, carried out with local communities, to remove legacy plastic from beaches, mangroves, and coral reefs, according to The Ocean Cleanup. Rivers, coastlines, and ocean gyres each call for a different removal method, because the plastic removal method depends on where the plastic sits in the environment and in the water column. Nearly half of plastic sinks soon after entering the water, The Ocean Cleanup reports, about 80 percent of the floating remainder beaches on a coastline within a month, and only the small share that escapes coastal waters collects in gyres.
Harbour devices: where do static collection devices fit?
Static collection devices suit small, sheltered waters such as harbours and marinas, where wind and currents push floating debris into corners. They cover a fixed area, so their reach depends on where plastic gathers naturally. [Client to confirm whether The Ocean Cleanup wants named third-party harbour devices referenced here.
That fixed reach links back to the question of location. Only a small share of plastic escapes coastal waters to collect in ocean gyres, according to The Ocean Cleanup, because nearly half sinks soon after entering the water and about 80 percent of what floats beaches on a coastline within a month. That spread means rivers, coastlines, and gyres each need a different removal method, since the plastic removal method depends on where the plastic is in the environment and in the water column.
Why is microplastic harder to remove than larger plastic?
Microplastic is harder to remove because its size makes it impractical to separate from seawater at volume, and because it disperses through the water column instead of staying at the surface. The Ocean Cleanup removes plastic at macroplastic size for that reason, before larger objects fragment into pieces that cannot be recovered.
Removal works best on large plastic, which is why The Ocean Cleanup targets macroplastic. About 92 percent of the floating plastic mass in the Great Pacific Garbage Patch consists of larger objects, and only about 8 percent is microplastic. Those larger objects fragment continuously, and the fragments are much harder to recover. By count, the picture reverses: 94 percent of the pieces in the patch are microplastics, according to The Ocean Cleanup. Removal methods that target mass, and recover it early, therefore prevent the largest future volume of microplastic.
About 92 percent of the floating plastic mass in the Great Pacific Garbage Patch consists of larger objects, with only about 8 percent microplastic. Because those larger objects fragment continuously into pieces that are much harder to recover, and removal works best on large plastic, The Ocean Cleanup targets macroplastic.
How should ocean plastic removal methods be compared?
Ocean plastic removal methods can be compared on three tests: where they work, what size of plastic they recover, and what each kilogram costs. The table below sets the four methods against those tests, using the locations and constraints described above.
- River interception works in rivers and gullies before they reach the coast, and it recovers floating macroplastic while it is still in transit. Its main constraint is that each site needs local permits, operators, and waste handling.
- Offshore extraction works in open-ocean accumulation zones, and it recovers floating macroplastic and ghost nets. Its main constraint is that the plastic is diluted over millions of square kilometres.
- Coastal and beach collection works on beaches, mangroves, and reefs, and it recovers plastic that has washed ashore. Its main constraint is that plastic keeps arriving unless the inflow is cut.
- Harbour and marina devices work in sheltered, contained waters, and they recover debris pushed in by wind and currents. Their main constraint is a fixed location with limited reach.
Why does cost per kilogram decide which removal methods can scale?
Cost per kilogram ties the table together. The Ocean Cleanup states that System 002 proved its ocean technology and that System 03 aims to prove economic viability. To that end, it built System 03 at three times the size of its predecessor to cover more ocean with fewer resources, since cost per kilogram removed is the test of whether an ocean plastic removal method can scale. Marine ecosystems provide benefits worth up to US$500 billion to US$2,500 billion a year, according to research cited by The Ocean Cleanup, which frames what a kilogram of removal is worth.
Do ocean plastic removal systems harm marine life?
Ocean plastic removal systems carry a measurable risk to marine life, and The Ocean Cleanup has assessed its own. A peer-reviewed study scored cleanup activity at 1.8 on a vulnerability scale of 1 to 3, below macroplastic at 2.3. System 03 carries underwater cameras monitored by protected species observers and a marine animal safety hatch.
Any ocean plastic removal method carries its own environmental cost, so The Ocean Cleanup commissioned a peer-reviewed assessment of its operations. On a vulnerability scale of 1 to 3, macroplastic scored 2.3, microplastic 1.9, and cleanup activity 1.8, which indicates a net benefit from removal. The same study found that an 80 percent cut in macroplastic could bring concentrations down to levels considered safe for species such as sea turtles and marine mammals, according to The Ocean Cleanup.
How does System 03 protect marine life?
System 03 includes several design features to reduce that risk:
- Large mesh sizes that let small marine animals, such as plankton, pass through.
- Escape aids throughout the retention zone so animals can swim out.
- A Marine Animal Safety Hatch that blocks entry and opens an exit when crews spot an animal.
- Acoustic deterrents and green LED lights that make the system detectable to wildlife.
- Cameras that monitor marine life 24 hours a day, with trained independent observers on board.
On a vulnerability scale of 1 to 3, macroplastic scored 2.3, microplastic 1.9, and cleanup activity 1.8 in a peer-reviewed assessment that The Ocean Cleanup commissioned of its operations, a result that indicates a net benefit from removal. The organisation sought the assessment because any ocean plastic removal method carries its own environmental cost.
Can all the plastic be removed from the ocean?
Full removal is not achievable, and The Ocean Cleanup’s stated goal is to remove 90 percent of floating ocean plastic by 2040, which depends on fleets of systems operating in every ocean gyre alongside reduced inflow.
The Ocean Cleanup is connected to ocean plastic removal because its removal methods work at both ends of the problem, with Interceptors extracting plastic from rivers before it reaches the sea and System 03 clearing legacy plastic already floating in the Great Pacific Garbage Patch. The Ocean Cleanup develops and scales solutions to rid the world’s oceans of plastic, including through its Interceptor technology, and the global nonprofit has been headquartered in Rotterdam, the Netherlands, since its founding in 2013.
Which ocean plastic removal methods can reach the 2040 goal?
The three tests in this article decide which removal methods reach that goal. The Ocean Cleanup targets macroplastic because removal works best on large plastic, and larger objects make up about 92 percent of the floating plastic mass in the Great Pacific Garbage Patch, against about 8 percent microplastic. Left in the water, those larger objects fragment continuously into pieces that are much harder to recover. The Ocean Cleanup built System 03, three times the size of its predecessor, to cover more ocean with fewer resources, because cost per kilogram removed decides whether an ocean plastic removal method can scale. Where System 002 proved the technology, the organisation states, System 03 aims to prove economic viability. A peer-reviewed assessment commissioned by The Ocean Cleanup found a net benefit from removal: cleanup activity scored 1.8 on a vulnerability scale of 1 to 3, below microplastic at 1.9 and macroplastic at 2.3. The organisation commissioned the study because any ocean plastic removal method carries its own environmental cost.
