by Katy Schaefer
Boyan Slat, a 21 year old Dutch inventor, entrepreneur, and wunderkind gained quite a bit of media attention in 2012 when he gave a TEDx talk proposing a radical plan to clean the world’s oceans. He devised a system that he claims could remove 7,250,000,000KG of plastic from the oceans in just five years per gyre. The public responded with hope, joy and donations. However, with the first official open ocean test launch happening in the second quarter of 2016, the marine biologists and oceanographers have begun to cry foul.
The tool Slat devised is a v-shaped floating barrier attached to the seabed. It is intended to catch the plastic deposited in the ocean by natural currents. Attached to this barrier is a non-permeable screen which is meant to catch plastic floating on the waters’ surface, while not disturbing other sea life. Once collected, the trash will be forced towards the center point of the structure, where a central platform will extract and store the plastic until it can be collected and sold for profit. This design won him numerous awards including being crowned 2014 Champion of the Earth by the United Nations, selected by TIME as one of the twenty five best inventions of 2015, and the maritime industry’s Young Entrepreneur Award. However, now that we are getting closer and closer to the launch date, there are several issues with the design and implementation that have been highlighted by other professionals in the field.
The problems with Slat’s plan begin with his design, in which he underestimates of the sheer size and power of the ocean. Slat’s cleanup plan’s success depends upon the condition that the structure remains moored. The average depth of the ocean is 4,000 meters, and the deepest known mooring is approximately 2,000 meters. The ocean’s surface is 315 million square kilometers—70 percent of the earth’s surface, and the plastic being collected isn’t exclusively in the gyres, it’s everywhere. The Ocean is also basically one giant corrosive force. Not only is sea life and salt corrosive to any mechanical object, the force of an ocean storm is enough to destroy almost anything in its path. This means that in the event of a storm, the entire system could be swept away or destroyed. There is also the issue of the depth that the screen designed to catch the plastic would reach. The plans for this structure are created with the assumption that the plastic would be more buoyant than the water and would thus float on the surface where it could be easily collected. However, researchers have shown that plastic can remain suspended in a water column at 100-150 meters due to wave action and sea state. Not only does this mean that Slat’s design wouldn’t capture this plastic, it shows that his estimation of how much plastic is in the ocean is incorrect and thus, his five year goal to clean a gyre becomes less and less realistic.
Another issue the structure will face comes from the life that exists in the ocean. Barnacles will attach to mechanical parts causing them to seize, while fish, squid, and birds will make the barge their home. This extra weight could submerge the structure, or at the very least change the path it would take. This then brings us to issues of entanglement. There will certainly be large animal life, like turtles, that could become trapped. However, the most concerning, while not the most glamorous of which, is plankton. There is no effective system of separating plankton from plastic. As it stands, the system Slat has in place would spin the plankton in a centrifuge at 50 RPM. If by some chance they were to survive the centrifuge, they would have had all of their most important parts ripped off, like their antennae and their feeding apparatus. Plankton are the basis of ocean life, and without them, or seeing any sort of drop off in their population, how the rest of the for chain will respond becomes a central issue.
The final complication that needs to be addressed is the economics of the project. The ultimate step of Slat’s plan is to sell off all the collected plastic to recyclers for a profit. However, there are multiple difficulties with the viability of this idea. Firstly, the two most common chemical components of plastic you might find in the ocean are polyethylene and polypropylene. Both of these have polymer chains of monomer hydrocarbon molecules. This is important because these particular molecules break down in UV light, something there is no shortage of in the open ocean. This means that the structural integrity of whatever the recycler might make with that plastic would be compromised. In addition to the decomposition of the plastic, one also cannot ignore the role of bio-fouling. Bio-fouling basically means that living things will attach themselves to all the plastic bits. Plastic can only be recycled if it is clean, which this would not be. Even if no living organism had made a home of the floating pieces, they would be saturated with toxic chemicals found in seawater. Next is the issue of transportation. Given the condition the plastic would be in, and the types that are most commonly fished out (think plastic bags), it would cost more to bring the material in than the recycler could make in profit, making the process uneconomic. The final issue is sustainability. There is a growing single use plastic input, which effectively means that no matter how much plastic Slat’s contraption was able to take from the ocean, it could never keep up with what was being tossed in.
Although Slat’s plan is ambitious, and his heart is no doubt in the right place, his design has too many issues to make it feasible at this point. He and his team have been looked at by multiple outside sources hoping to help improve the final product. Ultimately however, Slat’s plan seems optimistic at best. The success of Boyan Slat will reveal itself in time. Until then, we anxiously await the full scale deployment in 2020.
CONTACT INFO: @AgentStiv (ecowatch, fallacy cleaning Gyres), @rejectedbanana (Deep Sea News, The Ocean Cleanup),