Giant plastic sensor for cleaning the Pacific Ocean

When a Dutch teenager swam in the sea in Greece seven years ago, he was shocked to see more plastic than fish.

In fact, Boyan Slat was so appalled by the pollution that he quickly began campaigning for the oceans to be cleansed.

For a long time, few people have taken it seriously. There was a university dropout with a wacky idea that surely could never work.

But this weekend, backed by major investments and massive engineering, an extensive plastic collection system will be removed from San Francisco Bay.

Until now, plastic litter campaigns were focused on beaches, volunteers from around the world lifting bags and bottles on the banks.

Never before has anyone gone any further trying to get rid of the middle of an ocean and, despite sea trials and computer modeling, no one knows if the experiment will work.

Some experts fear that this effort will distract attention from the more pressing task of preventing plastics from entering the sea in the first place and that the operation may be detrimental to marine life.

But Boyan and his team at the nonprofit Ocean Cleanup believe that the sheer scale of plastic requires action.

So what are they trying to do?

Their target is the eastern Pacific and what is called the Great Garbage Patch, where circular currents have concentrated plastic in a large area.

The goal is to halve the amount of pollution in the patch every five years, so that by 2040, almost all pollution will disappear.

"We are in a hurry," says Lonneke Holierhoek, project manager of the project.

I meet her at the project headquarters in Rotterdam in offices much larger than I expected. The Dutch government is a major funder, with some companies and wealthy investors.

The project, with a budget of at least 20 million euros (18 million pounds sterling), has gone from a young man's vision to a serious international company.

There is a faint smell of algae and garbage. On the desks and on the ground, boxes filled with plastic fragments taken from the sea during previous expeditions recalled the task at hand.

"If we do not do it," Lonneke told me, "all this plastic will start to break down into smaller and smaller pieces – and the smaller the pieces, the more harmful and difficult they will be to extract from the marine environment."

As an engineer who has spent the last two decades working on offshore projects, she is not an activist but a rich work experience with huge offshore structures.

For her, the project is a determined effort to reverse the trend of pollution. "Rather than talking about it, contributing to problems or protesting against it, it is actually trying to solve it."

How will the project work?

The essential point is that the collection system is passive – there are no engines, no machines. Instead, it drifts, acting like an artificial shoreline, gently picking up any plastic in its path.

Like a giant snake, consisting of sections of tube, it is 600 m long and floats in the shape of a giant "U". Below, a screen will hang at 3 meters.

Because plastic floats just on the surface or slightly below the surface, it just drifts with the force of ocean currents. But as the collection system is also displaced by wind and waves, it should travel about one node faster, driving the plastic into a dense mass.

Fish should be able to swim underneath and, as the apparatus has smooth surfaces, the hope is that no fauna will curl.

The onboard cameras watch and, about every six weeks, a ship moves to pick up the tangle of concentrated plastic and bring it back to the mainland for recycling.

The plan is to use the recovered material to market a range of products deliberately "made from ocean plastic" and sold at a high price.

What are the disadvantages?

Some experts I spoke to fear that marine life will suffer.

Everything drifting in the sea is quickly covered with algae, attracting the plankton that attracts small and larger fish. Industrial fishing fleets actually deploy "fish aggregating devices" to serve as decoys.

Lonneke Holierhoek has an answer. An independent environmental study has shown that the impact can be minimized, she says, for example by making noise just before the plastic has come out to scare away the fish.

But Sue Kinsey of the Marine Conservation Society is among those who are not convinced. She admires the passion and inspiration behind the project, but says it could be dangerous.

"The major problem is that of the creatures that passively float in the ocean and can not really move – once in this chart, they will be trapped there in the inability to move," says she.

She also says that it's more cost-effective to clean the beaches rather than focusing on preventing the increase in the number of plastics reaching the oceans.

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Professor Richard Lampitt of the UK National Oceanography Center also applauds the outreach project, but believes that much of the plastic that enters the sea is flowing relatively quickly, so the l & # 39; effort will not make a big difference.

And it also highlights the carbon cost of constructing 60 collection devices as the plan goes ahead and ships shuttling around 8,000 tonnes of plastic per year.

"The cost / benefit ratio does not seem attractive at all," explains Professor Lampitt.

Back in Rotterdam, one of the project's scientists, Laurent Lebreton, is convinced that the effort is worth it and he shows me two examples of plastic waste impacting the natural world.

A small piece of white coral sprouted around the fibers of an old fishing net – a surprisingly shocking sight. And on the irregular edge of a plastic bottle, there are traces of unmistakable teeth left by a fish that took a bite.

"This plastic is swallowed and the fish is eaten and the plastic enters the food chain and ends up on our plates," explains Laurent.

"The solution is to ensure that plastic does not penetrate the natural environment and clean the plastic accumulated since the 1950s".

It will take three weeks for the system to be towed to the Great Garbage Patch, about 2,000 kilometers off the coast of California. The first meaning of the performance should be clear later this year.