Charles
Moore, the man who first discovered the now infamous Great Pacific
Garbage Patch in the North Pacific Subtropical Gyre, has famously
claimed that cleaning it up would be impossible: “Trying to clean up the
Pacific gyre would bankrupt any country and kill wildlife in the nets
as it went”, he’s proclaimed.
And there’s no denying that the plastic-ridden expanse of
the North Pacific, the largest of five oceanic gyres where plastics
collect in slowly rotating currents, is a challenging environmental
nightmare, one that can’t be fixed with a fleet of carbon-emitting and
net-dragging boats.
The Algalita Marine Research and Education
Foundation, where Moore works, describes the garbage patch as ‘a
“plastic soup”, where the plastic is distributed throughout the water
column’, taking up an area of the ocean roughly two times the size of
Texas. With most of the plastic broken into small pieces through
exposure to the sun’s ultraviolet radiation, the foundation presents
this disheartening analogy for those ambitious enough to think it can be
cleared: ‘Think of how difficult it would be to gather confetti from
along a stretch of beach. Now imagine the area you are trying to clean
is not only miles long, but also miles deep.’
The photodegraded plastic, which outnumbers plankton by a
ratio of six to one, is often mistaken as food by marine life and, even
when it doesn’t directly kill those that ingest it (and it reportedly
kills at least a million sea birds and hundreds of thousands of marine
mammals each year), it can enter the food chain, bringing with it a
whole host of undesirable chemicals – hormone disrupters like bisphenol A
and potential carcinogens like styrene monomers – that the plastic
releases as it degrades, as well as hydrophobic fertilizers and
herbicides that it absorbs in the marine environment.
It’s a bit of an overwhelming problem, and, with
environmental dilemmas like this, “the common response is ‘Well, that’s a
long way off. That’s for our children to worry about’”, according to
Boyan Slat. Speaking in the video of his TEDx talk in his home city of
Delft, Netherlands, Slat follows that assertion with a cheeky grin and
the statement: “Hello. Here I am.”
At the time of giving his talk, Slat was just 17 years old
and was presenting his concept for a passive oceanic cleanup system,
which grew out of a high school science project. Slat explains: “I
realised, back in high school, that there might be an alternative [to a
cleanup process based on vessels with nets that would be fishing for
plastic]. I wondered: why move through the oceans if the oceans can move
through you?
Instead of going after the plastics, you could simply wait
for the plastic to come to you, without requiring any added energy. An
array of floating barriers would first catch and then concentrate the
debris, enabling a platform to efficiently extract the plastic
afterwards. The ocean currents would pass underneath these barriers,
taking… sealife with it, preventing by-catch. An elegant idea. But when I
got asked to present this idea at the TEDx Delft conference, it wasn’t
much more than that – an idea.”
Though The Ocean Cleanup estimates it can collect the
majority of plastic mass from the world’s oceanic gyres, it does not
think it can collect any microplastics, particles less than five
millimetres (mm) (or even one mm, according to some researchers). In
fact, under the modelled conditions, no plastics smaller than two
centimetres were captured.
“There appears to be a sink for microplastics that is
already in place”, Slat tells me. “We don’t know what it is, but it
could be that fish are eating it and therefore they cannot be found
anymore near the surface of the water – there should be a lot more of
them, but there aren’t. It could also be that they sink, that they are
deeper in the water column – we have some evidence for that.”
Slat emphasises that, by capturing 95 per cent of the mass
of oceanic plastic, The Ocean Cleanup would prevent many microplastics
from being created, as larger plastic items photodegrade into
ever-smaller pieces in pelagic conditions. However, microplastics don’t
just come from larger bits of plastic – some start off micro, which is
of increasing concern to scientists and environmental campaigners.
‘Primary microplastics’ are popular in beauty products as
abrasives and exfoliants, especially in face washes, toothpaste, shaving
cream and shower gel – and these microbeads are now commonly made from
plastic rather than natural materials (be sure to read your ingredient
list!). Microplastics can also originate in household washing machines,
due to the shedding of synthetic textile fibres – in either case, these
tiny bits of plastic are too small to be extracted by sewage treatment
works, and slip through to marine ecosystems with devastating
consequences.
While there’s little that can currently be done about
microplastics that break away from larger masses, there’s now an
international campaign, ‘Beat the Microbead’, which was launched by the
Plastic Soup Foundation in 2012. As a result, a number of multinational
cosmetic companies have pledged to phase out microbeads, though many
have not set definite timetables.
Moreover, the Dutch government is
pushing for a ban in Europe, which would be similar to bans in some US
states; following concern about microplastic dispersion in the Great
Lakes, Illinois and New York have banned the manufacture and sale of
products containing microbeads, with Michigan and Ohio looking to follow
suit.
After presenting his idea at TEDx, Slat started studying
aerospace engineering, but, he says he couldn’t stop thinking about
ocean plastics and so turned to professors and industry experts to help
compile a list of 50 questions that needed to be answered to call his
idea a feasible solution.
He subsequently suspended his studies to set
up The Ocean Cleanup foundation, and used crowdfunding and the work of
many volunteers and professionals in many fields – including ecology,
engineering, fluid dynamics, plastic processing and maritime law – to
conduct an extensive feasibility study into the idea. This summer, the
foundation released a 530-page report claiming that the idea is indeed
feasible.
“The basic concept and all the basic principles – so, the
catching of the plastics, the concentration of the plastics – haven’t
changed and have in fact now been validated, but what has changed now is
some of the details”, Slat tells me, adding: “For example, how the
mooring systems work, what the platform looks like – at first it looked
like a fancy UFO crashed into the ocean; it now more closely resembles
an oil rig [see image on p.51].
Basically, when I made these concept
designs, I didn’t have any knowledge whatsoever, there was no one
helping me three years ago. Now, fortunately, having worked with a team
of 100 people, including 70 scientists and engineers – we’ve been able
to develop this.”
It’s mainly the details that have changed, and, Slat says,
they now have more accurate estimates for many aspects of the project.
The study conservatively estimates that there are 140,000 tonnes of
plastic floating in the North Pacific gyre – 119,000 tonnes of particles
larger than two centimetres and 21,000 tonnes smaller than two
centimetres (see boxout on microplastics on p.54).
Most of this plastic,
according to the study, is concentrated close to the surface of the
water, with mass decreasing exponentially with depth, leading to the
conclusion that the floating barriers should be placed at a depth of two
to three metres to collect the greatest mass of plastic pollution.
The design of these floating booms has also changed, as
tests found that long booms with high tension wouldn’t be able to work
with the movements of the waves, and in fact could ‘overtop’, likely
losing some of the plastic collected. The Ocean Cleanup has attempted to
address the problem with a design that sees boom and tension cable
separated, with booms connected to the cable every 60 metres. The booms
are comprised of floating buoyancy elements with weighted ‘skirts’ –
thin, impermeable and flexible sheets that direct the plastics – hanging
to a depth of two to three metres.
They will be positioned in a ‘V’
shape, and angled toward a central platform with the aim of
concentrating the plastic; the models show that 80 per cent of the
plastic that encounters the booms will be captured. It will then collect
at the moored processing platforms that Slat says look like oil rigs
(though some might think they’re remarkably like air traffic control
towers anchored to the sea floor), from which it will have to be picked
up by ship every 45 days.
Slat explains that this system is highly scalable and that
the percentage of plastics that it can capture depends on the scale of
deployment: “If you deploy a single system with a length of a hundred
kilometres, you would collect 42 per cent of the plastic in the Great
Pacific Garbage Patch, where about a third of all plastics from all
oceans combined can be found.
But if you deploy something that’s, say,
200 kilometres, you would collect about two-thirds of the Great Pacific
Garbage Patch. If you use a hundred-kilometre device and deploy it for
20 years, you would collect about 75 per cent, so it really depends on
these variables. We can say that the majority of plastics in this area
can be collected using this system.”
And it’s not just the collection of plastic that the
foundation is looking into – it’s also considering what to do with the
harvested material. The feasibility study involved collecting half a
tonne of plastic from a remote Hawaiian beach, considered to be a
‘representative’ sample of gyre debris. This waste was tested by
pyrolysis companies, which found that ‘the quality of the pyrolysis oil
obtained from the polyolefin fraction of marine debris is comparable to
that obtained as regular input in their pyrolysis plants’.
The cover of
the 530-page feasibility document itself was also made using ocean
plastics treated with a heat press. Slat proudly displays the finished
product saying: “You can still see that it’s made out of ocean plastic
because you have these weird colours that look kind of cool.”
Since completing the study, Slat tells me, they have also
done some experiments into recycling the plastic through injection
moulding, and that “the quality by far exceeded our expectations”. “The
injection moulding was 50 per cent polypropylene, 50 per cent
polyethylene. The only preprocessing was washing to remove any organic
contaminants. Of course, it will certainly be downcycling in a way
because you can’t use it for food packaging, and we’re still doing some
chemical analysis of it to see if there’s any contamination that we
should worry about.” That being said, he still anticipates any number of
things could be made out of the material – “computer screens or chairs
or anything you can imagine”.
Putting the plastic to good use will also offset some of
the costs of the project, and perhaps even make it profitable: “Because
of the premium of it being ocean plastic, I think there’s definitely a
market for it, and I’m confident that it can cover at least part of the
costs of the execution”, Slat says. The study estimates that it would
cost €317 million (£247.5 million) to remove 42 per cent of waste from
the North Pacific Gyre over 10 years; to break even, the project would
need to receive €4.53 (£3.54) per kilogramme of collected plastic.
But all this is still a few years off. Following the
triumphant launch of the feasibility study, The Ocean Cleanup created
another crowdfunding campaign, this time seeking US$2 million (£1.2
million) to proceed to the next phase of testing. When I spoke to Slat
several days before the deadline, the pledges were still US$70,000
(£42,900) short, and the situation was “rather tense”, though he assured
me the research would continue with or without the funding, albeit at a
much slower pace in the latter case. As it happened, the campaign
raised more than US$2.15 million (£1.32 million), making the next steps
much easier.
“Now, we’ll start the pilot stage and through a series of
upscale tests, we’ll work towards this large-scale operation of a pilot
in about three to four years’ time”, Slat explains. “We’ve shown that
the concept is likely feasible, but now we have to also make it
executable. There are some factors that primarily influence the costs as
well as the efficiency.
So, there is a large uncertainty of the amount
of plastic in the area, so that’s something that we will be working on.
And then there’s the variability of the current, which will likely
influence the collection efficiency. In the next year, we will mostly be
doing controlled environment tests, then we’ll go to coastal waters and
then in two years’ time, we’ll be ready to go to the centres of the
gyres to do tests there and deploy a large-scale device. That should be
the final stepping stone before actually doing it on the full scale.”
This article was taken from Issue
78
In the coming years, The Ocean Cleanup will also be
continuing to emphasise the importance of preventing plastics from
reaching the oceans in the first place: “Just because we have a way to
clean up what’s already out there, it shouldn’t be an excuse to continue
pollution, but now should be the time that we really do our best to
make sure that the tap is closed, as well”, Slat says, and indicates
that the project could also look at ways to intercept plastic before it
reaches the ocean.
So there is still a lot of work to be done, but there are
certainly reasons to be optimistic. And even the famous Garbage Patch
discoverer and cleanup naysayer isn’t overly pessimistic about the
project’s prospects: Slat tells me he had “a wonderful four or five hour
discussion” with Charles Moore about his concept, and the captain
“wasn’t too negative about it” (though he was “definitely sceptical”).
“Human history is basically a list of things that couldn’t
be done and then were done”, the tireless and optimistic young man
proclaimed when launching the feasibility study. Here’s hoping we can
soon add cleaning up the oceans to that list…
(image courtesy of 
Print
E-mail
Share