Facts So Romantic

This Floating Contraption Could Scoop Out Absurd Amounts of Ocean Plastic

A 21-year-old named Boyan Slat says he can solve one of the greatest ecological disasters of our age: the build-up of vast amounts of plastic in our oceans. The young Dutchman, often photographed in a t-shirt and shorts, says he’s designed a structure that will harvest and recycle much of that waste.

Gobbler of Plastic: Artistic conception of Slat’s array.Erwin Zwart/The Ocean Cleanup

Made from a combination of steel and polyester, Slat’s plastic-collecting structure floats on the surface of the ocean near the center of a gyre, a system of rotating ocean currents created by wind and the Earth’s rotation. There are six major gyres in the world’s oceans and, when plastic approaches one, it gets trapped by the churning currents and accumulates, over time forming large garbage patches. Slat’s array faces the current, letting it do the work of pushing plastic into the array’s arms. It’s V-shape structure—composed of long connecting booms that stretch for 100 kilometers (60 miles) each and anchored to the seabed every 4 kilometers with long polyester straps—encourages plastic to flow toward its center, where a solar-powered conveyer belt extracts, separates, and stores the plastic in a tower for pickup.

Slat has captured the imagination of both scientists and investors worldwide—but he’s also riled critics who argue he’s in over his head. Oceanographers Kim Martini and Miriam Goldstein, for example, reviewed Slat’s project in 2014 and faulted it for relying too much on average versus extreme measurements of the ocean, and for not having a workable solution for biofouling, the corrosion of surfaces by barnacles, algae, and other microorganisms. This September, members of the 5 Gyres Institute, a nonprofit group devoted to eliminating plastic pollution, argued that Slat’s model doesn’t account for organisms that passively float near the surface and can’t swim to escape the array, including the purple janthina snail and the wind-driven velella velella jelly.

“I didn’t have a clue about the forces we would have to deal with,” Slat concedes. But he sees this as an advantage. “I think the fact that I didn’t know a lot about off-shore engineering or oceanography actually helped me to put this forward, because if I hadn’t been that naïve, I probably would have dismissed the whole notion within a split second.”

Nautilus caught up with the young entrepreneur, engineer, and inventor this past August, when he and his team at The Ocean Cleanup were refining their design and getting ready to launch an expedition to gather data on the great Pacific Ocean garbage patch, which will tell them more about the feasibility of their project. Slat plans to install his first test model, a 2-kilometer structure, in the waters near Japan next year. He aims to have the 100-kilometer model collecting plastic in 2020; in five years’ time, he projects that almost half the plastic in the great Pacific Ocean patch will be removed by this single model.

Slat’s voice is young, but confident. During our Skype conversation, he spoke earnestly about plastic pollution and his vision for eliminating it. He appears to have bypassed the “what am I going to do with my life?” angst that afflicts people in their early twenties.


How old were you when you realized you wanted to devote yourself to cleaning plastic from the oceans?

When I was 16 and diving in Greece, I came across more plastic bags than fish. I then started to think about: Why can’t we clean it up? I quickly realized the ocean is quite big and so if you were to go out there with boats and nets, it would take basically forever. Then I had to do a high school science project, and for a year I used that time to figure out why it’s difficult to clean up. Eventually I realized that these [plastic] patches are rotating, and they don’t stay in one spot, which people told me is another reason why it couldn’t be done. But I thought: Well is that really a problem or could I also use that as a solution? Why move through the ocean if the ocean can move through you?

How will you cover the cost of this large-scale cleanup?

Right now we estimate that the cost to get it out of the water will be 4.5 euros per kilo based on the least amount of material in the water. But it’s really quite possible that there is 10 times as much plastic in the water, which would mean that the cost per kilo to get it out of the water would be divided by 10. So, it would only be 45 cents per kilo, which would of course be a world of difference.

Are you also assuming that your operating costs will be lowered the more plastic you harvest and recycle?

We’re assuming that. We’ve done tests with material. We got plastic from the Hawaiian shoreline, which we assume comes from the gyre, and that it’s the same quality of the stuff that we have in the middle of the ocean. It shows us we can make really high quality products out of this. And there have been over 30 companies that have shown interest in buying up the material, once we’ve taking it out of the ocean.

Indeed the more kilos there will be, the cost per kilo will be less, and the less of a premium will be required to pay for the material to cover the cost. Considering this huge uncertainty on the amount of the plastic in the ocean, as well as some uncertainty as to the cost of the execution, which we currently predict to be € 320 million, we cannot make any prediction yet as to whether it will cover all of the costs, but it will certainly cover part of the costs.

Will your structure be able to capture plastic smaller than 2 cm, which some claim makes up 98 percent of all ocean plastic?

This is incorrect. According to a 2014 study by Marcus Eriksen, of the 5 Gyres Institute, and colleagues, about 98 percent of the mass (not count) is in plastic larger than 5 mm. We’re currently using our scale model tests to better study how small a particle we can catch, but computer models show this is somewhere between 1 mm and 2 cm.

If we were to wait [a few] more decades, then basically we wouldn’t have the time to put a stop to the breakdown into smaller stuff, thereby increasing the amount of micro plastics. And then we would a) have a serious ecological disaster and b) it will then be very difficult to get it out of the ocean again. So hence we really should urgently address this and develop the technologies required to get it out of the water. So, certainly there will be some minute particles that will go underneath it, but we shouldn’t live under the illusion that we will get every last piece of plastic out of the ocean. Really the goal is to get as much of the material out of there for as little budget as possible.

Detractors have said that your design is too fragile, and it won’t be able to withstand the force of huge ocean waves.

The whole design philosophy has been to move with the waves rather than try to fight them. If you try to fight them, you will most certainly lose. We just made a way to make the barrier and the moorings extremely flexible so they can follow the waves almost like an inverted pendulum, and thereby the loads aren’t being transferred to the moorings.  We calculate that there are about 200 tons per 4 kilometers, so it’s really within the boundaries of what materials and cables can do.

Will your structure harm sea creatures, such as zooplankton, by getting caught with the plastic in the centrifuge, as some have alleged?

This will be tested with real life examples, which is what we will be doing in Japan, but there is no reason to assume that it will result in any problems. Our prediction is that fish will be able to swim underneath it and plankton will be taken by the current, because they are negatively buoyant, meaning that there’s no reason to assume that they will get trapped.

How will you keep living organisms from attaching to the structure or biting it, without also harming them?

Biofouling is something we are looking at, and we’re actually doing tests with coatings. They are nontoxic coatings, which should be able to mitigate that problem. If that wouldn’t solve it, there is the rate at which the biofouling occurs. It’s so slow. It peaks at about a few 10 kilos per square meter. That’s nowhere near the buoyancy of these barriers. In other words, it’s really not a concern for us, but still we are looking into it.

Do you think innovative cleanup projects ultimately encourage people to be litterbugs?

If the fate of the oceans were to rely on the individual actions of 7.2 billion people, I wouldn’t be able to sleep at night. I really think we should use our technological ingenuity to our advantage here. But obviously it’s a combination of both preventing more stuff from entering the ocean and cleaning up what’s already out there.

I don’t think there really is a debate. Actually I think they highly complement each other. Because we are communicating what we are doing now, hundreds of millions of people know about this problem.

It’s very uninspiring thing to say that “since we can’t clean it up, the best thing to do is not make it worse.” If that really were the case, I don’t know I’d be that motivated to work on this problem. Having the prospect of a future that’s better than the present, instead of just not worse than the present, I think that’s an incredibly powerful way to get people involved in this.


Regan Penaluna is a senior editor at Guernica magazine.

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