How to rid the oceans of plastic? Ocean Cleanup Project

Ocean Cleanup Project arrayWhen you think of the “Great Pacific Garbage Patch” you might envision an area in the ocean full of yogurt cups and other debris.

Some say it’s the size of Texas and visible from space. Why doesn’t anyone do something about it?

Actually, the trip to the patch has broken the yogurt cups down to tiny little pieces. You can’t see it unless you’re there.

And the fragments aren’t as close together as you might imagine. The plastic is actually a bigger problem that way. And unfortunately, the ocean has at least five gyres, rotating currents where plastic can float in, but not out.

Albatross carcass with plastic -- ocean cleanup project

Albatross carcass with plastic

Plastic in the ocean presents multiple problems

  • It looks like food to marine animals. They eat it, but can’t excrete the larger particles.
  • A bird can fill its stomach with plastic to where it can’t eat any more and slowly starves.
  • Plastic bioaccumulates. That is, an animal low on the food chain eats plastic, and the plastic becomes part of its body. And part of the body of whatever eats it. And part of the body of everyone else higher on the food chain, including us.
  • No one knows how much plastic is there.
  • We can send ships “fishing” for plastic, but they will gather up fish and other marine life as bycatch.
  • It is impossible to remove microscopic particles without also removing plankton, without which all other marine animals would eventually die.
  • Whatever plastic is removed from the ocean must be returned to land. Then what?

And something else that may be a problem or not: plastic absorbs much more chemicals and pollutants than seawater. That means that the plastic in the ocean is more toxic than plastic on land. It also means that chemicals are in the plastic, not the water.

As hard as it is to remove the plastic, it would be much harder to remove dissolved chemicals from the water.

The Ocean Cleanup Project

Boyan Slat, ocean cleanup project

Boyan Slat

A young Dutchman named Boyan Slat devised a plan that he claims can clean the plastic out of the ocean in five years. He calls it the Ocean Cleanup Project (OCP).

Instead of sending out ships with nets to chase the plastic, he proposes spanning booms between platforms moored to the seabed.

Slat determined that the platforms should be in the shape of a manta ray to withstand the most extreme conditions.

The ocean current, instead of being an obstacle, becomes the means to concentrate the plastic and divert it along the booms, where it can be more reasonably removed. There are no nets to catch fish.

In principle, this method reduces bycatch to the vanishing point. Slat claims that plankton can survive the centrifuges that separate the smallest plastic from the water. It can simply be returned to the ocean.

Selling the plastic on land will bring in more than enough money to pay for the project.

In his TED talk, Slat claimed that previous researchers have thrown up their hands at the prospect of cleaning up the gyres. They focus instead on education and other means of prevention.

That part of the talk appears to be a direct slap at 5 Gyres, a highly respected non-governmental organization that specializes in research and education on marine plastics.

Criticism of the Ocean Cleanup Project

Scientists at 5 Gyres have not thrown up their hands. They had already concluded that cleaning up the plastic is not only difficult, but undesirable. Naturally, they did not appreciate a teenager lecturing them on the proper means of dealing with the problem.

5 Gyres and other likeminded critics offer some technological criticisms:

  • The OCP can only pick up plastic that’s 2 cm or larger, but 98% of plastic in the ocean is 5 mm or smaller.
  • Therefore, by the time it gets into the ocean, it’s already too late to collect it.
  • The platforms must be anchored to the ocean floor. The water where the OCP plans to operate is twice twice as deep as the current maximum depth for mooring structures—up to 4,000 meters.
  • OCP doesn’t account for biofouling, the effect microbes have when they grow on a plastic surface—such as most of the equipment OCP requires.

Beyond these difficulties, cleaning the plastic already in the gyres does nothing to prevent the flow of plastic into the ocean. It doesn’t treat the real problem—that we manufacture and use disposable plastic in the first place.

ocean cleanup project

Crew inspecting a proof-of-concept barrier, Azores, 2014

Once the OCP gets plastic trash back to land, it has soaked up too many chemicals to be recyclable. It has also been bleached by the sun and biofouled by microbes.

[Be that as it may, waste plastic can be converted to fuel either through pyrolysis or gasification.]

At best, the project only moves the waste from one place to another.

Slat claims his process is cheaper than the more traditional use of nets. But it’s not the cheapest way to clean the ocean.

It would be simpler and less expensive to clean up beaches so that the plastic litter there doesn’t get into the ocean, or back as the case may be. The largest items in the gyres, discarded fishing nets, harm shipping. If fishing companies had to lease the nets, return them, and pay a significant fine for lost nets, no one would discard them.

Booms as proposed for the OCP would be much more efficient placed at the mouths of rivers and other places “upstream” from the gyres.

More serious, critics claim that OCP will do actual environmental harm. Yet it has not conducted an environmental impact statement. Slat claims that marine life can swim under the booms and won’t get caught. Some marine life, jellyfish for example, doesn’t swim. It floats on the surface. It will become bycatch despite Slat’s claim that OCP will minimize that problem.

Scientists who collect and study plankton must do so very carefully. It doesn’t easily survive being caught in a regular manta net. How can it really survive its ride in a centrifuge?

The process of anchoring platforms to the ocean floor will disrupt deep ocean ecosystems. These systems, with their slow-growing animals and plants, are easily damaged and cannot quickly recover.

Boyan Slat, of course, disputes each of these criticisms.

Wicked problems

Ocean cleanup project, plastic particles

‘Codends’ filled with plastic particles after trawling the Great Pacific Garbage Patch for one hour.

This controversy is not a matter of scientists arguing with some kid. Slat recruited a group of 100 volunteer engineers and scientists. They conducted a year-long feasibility study.

The full report is 528 pages, and the summary is 16 pages. Both are available for download as PDFs.

To some extent, then, the dispute between OCP and 5 Gyres amounts to a turf war among scientists.

Ocean pollution is not simply a scientific or technical problem. It has social and cultural aspects. Engineering problems of this kind, known as wicked problems, are difficult to define. Once defined, they have no strictly scientific, social, cultural, or technological solution.

Narrowing the gap between what is and what ought to be requires a multifaceted approach. And so the tagline on 5 Gyres’ website is Science, Education, Activism. Education and activism likewise have their limitations.

Once people become comfortable with a habit, they don’t want to be educated about it. Pollution in the ocean seems like someone else’s problem, so “someone else” should be responsible for solving it. Littering, a root cause of ocean pollution, doesn’t seem like a problem to the litterer.

Activism seems to mean some form of pressuring government and business to do something or stop doing something. It allows activists to think they’re dealing with a problem. It doesn’t actually require them to change any of their own habits. Meanwhile, activists too easily fall into a smug superiority that turns people off.

Is OCP simply a stab at a technological fix to a wicked problem? From its website, it appears to understand that it can’t, by itself, provide a complete solution. No one in their right mind claims that cleaning up a mess is a bad thing. It can be a piece of the solution. But it must be done in ways that minimize causing other problems.

Sources:
How Big is the “Great Pacific Garbage Patch”? Science vs Myth / National Oceanic and Atmospheric Administration Office of Response and Restoration
The Ocean Cleanup Project website
Why the Ocean Clean Up Project Won’t Save Our Seas / 5 Gyres
How the Ocean Cleanup Array Fundamentally Misunderstands Marine Plastics and Causes Harm / Max Liboiron (Discard Studies, June 5, 2015)

Photo credits:
Albatross skeleton. Some rights reserved by Sea Studios Foundation
All others. The Ocean Cleanup Project.


Leave a Reply

Your email address will not be published.