Sustainability

Pilot deployed to fight plastic pollution in North Sea

The barrier in position in the North Sea

The first prototype of an oceanic barrier that could catch up to 80 per cent of the surface plastics that it encounters is ready to be installed later this week, marine litter initiative The Ocean Cleanup revealed yesterday (22 June).

The prototype will be deployed in the North Sea, 23 kilometres off the Dutch coast, where it will be positioned for one year.

The organisation’s founder Boyan Slat was just 18 years old when he founded The Ocean Cleanup in 2013. His vision was to create long floating barriers that would remain stationary in the water and use the ocean’s current to collect the plastics that blight the Great Pacific Garbage Patch, an area of the Pacific ocean created by rotating ocean currents (or gyres) that is thought to contain a third of the world’s oceanic plastic.

The technology of The Ocean Cleanup is based on deploying the barriers to act as an artificial coastline and passively catch and collect ocean debris. The barriers are designed to catch plastic while letting most of the ocean current pass underneath the structure, carrying away sea life and preventing by-catch. The plastics are then channelled towards the centre of the structure, allowing for a central platform to extract and store the collected plastic until it can be transported to land for recycling.

Aims of the North Sea prototype

The aim of the North Sea prototype is to test the resilience of the floating barriers during extreme weather, rather than its ability to collect plastic. Sensors on the 100-metre floating barrier will detect the motion of the prototype and the loads it is subjected to. This data will be collected and used by engineers to develop a fully resistant system that will be able to withstand the conditions that could arise during the cleanup of the Great Pacific Garbage Patch.

The North Sea experiences much harsher weather conditions during minor storms than the Pacific Ocean experiences during exceptionally heavy storms, making the test site an ideal location to evaluate how the barriers fare in severe weather conditions. 

In preparation for full deployment in the Pacific Ocean in 2020, The Ocean Cleanup in summer 2015 undertook a ‘Mega Expedition’, in which 30 vessels crossed the Great Pacific Garbage Patch simultaneously to produce a high-resolution map of the plastic pollution problem. Meanwhile, the team has advanced its design through a series of upscaling tests. The 1:1 scale test in the North Sea is the culmination of this phase, which will be followed by array testing, leading up to full deployment.

A ‘key step towards plastic free oceans’

Weapon against North Sea plastic pollution ready to go
The prototype in Scheveningen harbour – The Hague
At the launch of the prototype yesterday (22 June) Slat stated: “This is a historic day on the path toward clean oceans. A successful outcome of this test should put us on track to deploy the first operational pilot system in late 2017.”  

Slat also recognises that in order for the test to be considered a success the prototype does not necessarily have to make it back in one piece, estimating there to be “a 30 per cent chance the system will break”.

The Dutch Government and dredging and marine contractor Royal Boskalis Westminster N.V. are two of The Ocean Cleanup’s main partners and were represented at the unveiling of the prototype.

Dutch Environment Minister Sharon Dijksma commented on the prototype: “I hope that with the help of the Dutch government, Boyan’s prototype will turn out to be the successful solution for cleaning up the mid-ocean gyres. This is crucial to prevent permanent damage to the environment and marine life, due to the degradation and fragmentation of plastic waste materials.”

Boskalis CEO Peter Berdowski, added: “It has been inspiring to work with The Ocean Cleanup. Now that everything is ready, we are looking forward to the really exciting next step, with the transportation and installation of the barrier. I wish Boyan and his team success with their journey towards a plastic-free ocean.”

Development of The Ocean Cleanup system

Charles Moore, the oceanographer who first discovered the Great Pacific Garbage Patch, stated that cleaning up the Pacific Ocean would be an impossible task that would “bankrupt any country and kill wildlife in the nets as it went.”

Weapon against marine plastic deployed in North Sea
Sharon Dijksma, Boyan Slat and Peter Berdowski
Indeed the task is a challenging one, especially considering the great expanse of the Pacific Ocean and the fact that much of the plastic has been broken down into very small particles due to exposure to the sun’s ultraviolet radiation.

Slat’s idea for an ocean cleanup system stemmed from a high school project and he presented his idea at TEDx when he was just 17. After putting his studies in aerospace engineering on hold, Slat set up The Ocean Cleanup foundation, using crowdfunding and the work of both volunteers and professionals to conduct a study into his idea. 

Working with a team of 70 engineers and scientists Slat has been able to develop and improve the design for the system. Feasibility studies have estimated the floating barriers to have the potential to passively collect 80 per cent of the plastic pollution that passes through.

Extensive computer modelling and scale model testing by the Deltares research institute and in the Maritime Research Institute Netherlands (MARIN) offshore basin facility have preceded the North Sea test.

Should the North Sea test be a success the next stage of the process would be the Coastal Pilot, whereby a 2,000 metre long capture system would be deployed off the coast of Tsushima Island in Japan. The group hopes to carry out these pilot tests in the second half of 2017. 

Eunomia suggests beach action more beneficial in plastic fight

Last month, Eunomia Research & Consulting released the results of research and concluded that the fight against plastic pollution in the world's oceans should start on beaches, rather than in the sea itself. 

Eunomia says that barely one per cent of marine plastics are to be found floating at or near the ocean’s surface, with an average of less than one kilogramme (kg) found in each square kilometre (km2) of ocean. Though this concentration increases at certain mid-ocean locations, with the highest concentration recorded in the North Pacific Gyre at 18kg/km2, 94 per cent of plastic that enters the ocean ends up on the sea floor. There is, Eunomia says, now on average an estimated 70kg of plastic in each square kilometre of seabed.

More effective clean-up measures, it suggests, could be carried out on beaches, where the amount of plastic is estimated to be around five times greater than the ocean’s surface, and at a much higher concentration – 2,000kg/km2.

Presenting the findings at an event held by the consultancy, Chris Sherrington, Principal Consultant at Eunomia, said: “When plastic does get into the sea, it’s clear that efforts to remove it from the beaches are extremely valuable. They’re generally more accessible than the mid-ocean, there’s more material there overall than there is floating, and it is much more concentrated on beaches.”

For more information on The Ocean Cleanup project, see our feature profile of Boyan Slat from Resource 78.

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