2 2 CHAPTER 1.1 ABSTRACT The research described in this feasibility report indicates that The Ocean Cleanup Array is a feasible and viable method to remove large amounts of plastic pollution from a major accumulation zone known as the Great Pacific Garbage Patch. Computer simulations have shown that floating barriers are suitable to capture and concentrate floating plastic debris. Combined with ocean current models to determine how much plastic would encounter the structure, a cleanup efficiency of 42% of all plastic within the North Pacific gyre can be achieved in ten years using a 100 km Array. In collaboration with offshore experts, it has been determined that this Array can be made and installed using current materials and technologies. The estimated costs are 17 million in total, or 1.7 million per year when depreciated over ten years, which translates to 4.5 per kilogram of collected ocean debris.
3 4 CHAPTER AUTHORS
4 6 7 list of authors and affiliations Boyan Slat Dr. Agnes Ardiyanti Emile Arens Msc. Evelien Bolle Hyke Brugman J.D., LLM., Ph.D. Holly Campbell Msc. Pierre-Louis Christiane Ph.D. Bill Cooper Msc. Marijn Dekker Msc. Stella Diamant Msc. Bernd van Dijk Msc. Mark van Dijk Msc. Sjoerd Drenkelford Ir. Jabe Faber Msc. Fransesco F. Ferrari Dr. Norbert Fraunholcz John Clinton Geil Msc. Christian Göbel Bsc., CPA Dario Grassini Bsc Joost de Haan Msc. Jort Hammer Richard G. Hildreth Tadzio Holtrop Edward Hornsby Sam van der Horst Nick Howard Hester Jansen Bsc. Wouter Jansen Jochem A. Jonkman LLB, LLM Nicholas P. Katsepontes PhD. David Kauzlaric Bsc. Raphael Klein Founder and CEO, The Ocean Cleanup Foundation Personal title Huisman Equipment BV, Schiedam, the Netherlands Personal title internship Engineering, Design & Innovation, Hogeschool van Amsterdam, the Netherlands Instructor at the Oregon State University Personal title University of Califonia-Irvine, U.S. MSc student TU Delft, Delft, the Netherlands Personal title Personal title Personal title Personal title USG engineering Personal title Recycling Avenue BV, Delft, the Netherlands Co-founder, International Ocean Law and Science Institute. J.D. Lewis and Clark Law School. A.B. Occidental College, Assistant Attorney General for the State of Oregon Instituto Federal Rio Grande do Sul Personal title MSc student TU Delft, Delft, the Netherlands Personal title Board of Directors, International Ocean Law and Science Institute. J.D. University of Michigan; Frank Nash Professor of Law and Director of the University of Oregon Ocean & Coastal Law Center Personal title Personal title Personal title Personal title Personal title MSc student TU Delft, Delft, the Netherlands Recycling Avenue BV, Delft, the Netherlands Retired, personal title Freiburg Institute for Advanced Studies, University of Freiburg, Germany; Laboratory for Simulation, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany Freiburg Institute for Advanced Studies; Laboratory for Simulation, Department of Microsystems Engineering (IMTEK), University of Freiburg, Germany MSc student TU Delft, Delft, the Netherlands PhD. Dr. Ir. Bsc. Dr. Bsc. Msc. Msc. Dr. Msc. Msc. Dr. Dr. Bsc. PhD. Dr. Bsc. Ir. PhD. Bsc Msc. Bsc. Bsc. Bsc. MSc. Bsc. Dr.Ir. Stephan Koch Tim Landgraf Remko Leinenga Christophe Limouzin Ezra Hildering van Lith Jaime López Wart Luscuere Richard Martini Maximilian Michels Bonnie Monteleone Kelly Osborn Senol Ozmutlu Elena Pallares Leonid Pavlov Herbert Peek Kauê Pelegrini Gabrielle S. Prendergast Maira Proietti Jill Randolph Alexander Rau Julia Reisser Marleen Roelofs Sebastiaan van Rossum Rebecca Rushton Stefan van Ruyven Bruno Sainte-Rose Sneh Samir Sebastiaan van Schie Moritz Schmid Katherine Schmidt Nandini Sivasubramanian Kathleen Laura Stack Paula Walker Adam Walters Nathan Walworth Niklas Wehkamp Robbert Zuijderwijk Jan de Sonneville ETH Zürich, Institute of Geophysics Freie Universität Berlin, Berlin, Germany El-tec Elektrotechniek BV MRE Business Development Manager, Vryhof Anchors, Paris, France student TU Delft, Delft, the Netherlands Personal title Personal title Personal title MSc student, Computer Science, Freie Universität Berlin, Berlin, Germany Personal title Personal title Projects Director, Vryhof Anchors, Capelle aan de Yssel, the Netherlands Labaratori d Enginyeria Marítima (LIM-UPC) Engineer, ATG Europe, Noordwijk, The Netherlands El-tec Elektrotechniek BV Polymers Laboratory, University of Caxias do Sul, Brazil Personal title Universidade Federal do Rio Grande Personal title MSc student, Computer Science, Freie Universität Berlin, Berlin, Germany The University of Western Australia Personal title MSc student TU Delft, Delft, the Netherlands; intern, Vuyk Engineering Rotterdam BV Third-year law student at the University of Oregon Huisman Equipment BV, Schiedam, the Netherlands LEMMA, Paris, Head of Office MSc student TU Delft, Delft, the NetherlandsBSc student TU Delft, Delft, the Netherlands Takuvik Joint International Labatory, Laval University, Canada; CNRS, France; Département de biologie et Québac-Océan, Université Laval, Québec, Canada Personal title Intern, Freiburg Institute for Advanced Studies, Freiburg, Germany Personal title Co-founder, International Ocean Law and Science Institute. J.D. Lewis and Clark Law School Oceans, Coasts, and Watersheds Fellow at the University of Oregon School of Law University of Southern California MSc. in Microsystems Engineering Student Leiden University, Leiden, the Netherlands Personal title
5 8 CHAPTER COPYRIGHT INFORMATION Version 2.0 Copyright 2014 by The Ocean Cleanup All rights reserved. This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a review. Printed in The Netherlands First Printing, June 2014 Version 1.0 is available on request. The Ocean Cleanup Stevinweg CN Delft The Netherlands theoceancleanup.com Cover and book design by HOAX Graphic Design Book Cover made from 100% Ocean Plastic (90% PE, 10% PP est.). Please Recycle.
6 10 CHAPTER REVIEWERS In the Ocean Cleanup report several options have been proposed for the boom, the skirts, the station keeping system, and the installation procedures. Through a series of preliminary feasibility assessments, mainly through simplified time domain dynamic models, the fundamental challenges of this novel concept have been individuated. A series of conceptual/preliminary technical solutions for these challenges are proposed, and most importantly the areas to be further investigated have been individuated. As a result, a first methodology for the design and analysis has been established. The Ocean Cleanup s exploratory CFD simulations use measured and modeled plastic distribution and oceanic conditions to determine the appropriate shape for their passive barrier concept. They also determine reasonable estimates for the efficiency of their design in collecting plastic debris of different sizes and densities. Although the design is unable to remove the smallest microplastics from the ocean, the high efficiency of the barriers in dealing with larger plastics would significantly reduce the overall mass of plastic debris in the North Pacific Subtropical Gyre. Before release, this document was evaluated for scientific falsities by a selected group of scientific peers, as a response to the requests of the authors. The independent scientists outlined in this chapter have agreed to the conclusions, exclusively based on their own fields of knowledge. The Ocean Cleanup Foundation and the authors of this report highly appreciate critical feedback, as well as suggestions for future work. Please send your input to: If you are interested in contributing to the success of our future work, please visit: Based on the conclusions in the report, the concept seems to be challenging but technically within the capabilities of state-of-the-art offshore engineering technology. Maurizio Collu, PhD, CEng Cranfield University, Offshore Renewable Energy Engineering Centre It is commendable that The Ocean Cleanup feasibility report brings together a vast array of concepts and disciplines that are brought across in an ordered and understandable way. The summarized description of the oceanography associated with the subtropical ocean gyres, where plastics are believed to be concentrated, is accurate, albeit it being generalized. The summary provides a good starting point of knowing where to focus the core of the project. Before full project implementation, I would suggest that more regionally specific analysis is completed on the gyres that The Ocean Cleanup intends to target, as this would provide efficiency to the cleanup process. Dr. Sebastiaan Swart Senior Researcher Southern Ocean Carbon and Climate Observatory Council for Scientific and Industrial Research (CSIR) Nicole Sharp, Ph.D. Aerospace engineer and author, FYFD The strategy of the study is conventional and efficient, with a first two-dimension analysis of the ocean flow around the boom and the skirt, and a particle model to have a first idea of the plastic parts potentially captured, depending on their size, density and depth. Despite some mesh size discontinuities, and the lack of boundary layer on the skirt degrading the flow precision near the wall, the results give a good idea of the efficiency of the system and the influence of the parameters. Then two D studies are completed to analyze the effect of the boom angles on the flow and the catch probability. A large scale simulation is performed with COMSOL and gives the D flow with several boom angles. Some hypotheses are not clear (condition used on the boundary at the end of the barrier and on the barrier, pressure gradient due to gravity not present at the outlet), but the results give more information on the effect of the boom angle. The finer study with CFX models the barrier more precisely, but with a too coarse mesh near the skirt and a domain too small to impose a pressure at the outlet. Nevertheless, the studies give the same parameters range which allow the particles to be caught, and a good idea of the efficiency of the global system. Stéphane Dyen Design team manager and CFD expert of Hydros / Hydroptère Suisse SA
7 12 TABLE OF CONTENTS 1 TABLE OF CONTENTS 1. Introduction The Plastic Lifecycle is Broken A Brief History of Plastic Plastic in the Oceans Breaking the Cycle What is the Problem Observations of Oceanic Plastic Pollution Plastic Pollution as Quantified by Net Tows Plastic Pollution as Quantified by Visual Observations Plastic in the Marine Environment Ecological impacts Entanglement Ingestion Invasive species Economic impacts Direct and Indirect Costs Ecotoxicological impacts Toxic Additives in Plastic Absorption of Contaminants by Plastic Transfer of Contaminants to Organisms Arguments for a cleanup Trends in Plastic Usage Natural Plastic Loss from the Gyres Moral arguments Conclusions Cleanup Challenges Scale and Depth Plastic Size and Depth Distribution Destructive Marine Environment Environmental Impact Legal Challenges Alternative Cleanup Concepts Drone-based Concepts Vessel-based Concepts Floating Islands Comparison of Concepts Our Concept The Array The Catching Phase The Concentration Phase The Collection Phase Main Advantages Feasibility study objectives Definition of Feasibility Main Questions Overview of the Study The Gyres Introduction to subtropical gyres The Information of Subtropical Gyres The North Pacific Subtropical Gyre The South Pacific Subtropical Gyre The North Atlantic Subtropical Gyre The South Atlantic Subtropical Gyre The Indian Subtropical Gyre Plastic Pollution Hotspots Mass of Ocean Plastic Mass of Millimeter-sized Plastics Mass of Centimeter to Meter-sized Plastics Total Mass of Floating Plastic in the North Pacific Garbage Patch Depth Profile of Plastic Pollution: A Pilot Study Materials and Methods Results and Discussion Determination of Location Possible Locations Based on Distribution Models Possible Locations Based on Ocean Depth Possible Locations Based on Plastic Measurements Choice of Location Environmental Conditions Waves Wind Currents Plastic Drifting Causes Determination of Array Length and Cleanup Time Van Sebille Model Model Explanation Methods Results Lebreton Model Working Principle The Goal Optimal Location Optimal Orientation Conclusions Consideration between Array variables Booms and Moorings Basic Overview Chapter Contents Concept Introduction Input Parameters Boom concepts Design Requirements Boom Concepts
8 14 TABLE OF CONTENTS 15 TABLE OF CONTENTS Solidworks Contest Concepts Rigid Steel Boom Flexible Polymer Boom Conclusions Boom Capture Efficiency Problem Description Simulation Methods Simulation Model Input Values for the Model Results and Discussion Velocity Flow Fields Particle Transport and Wall Interaction Influence on Parameters on Particle Trajectories Conclusions Modeling of Boom Angle Comsol Multiphysics 4.4 D CFD Model Model Summary Results and Discussion Summary and Recommendations ANSYS CFX D CFD Model Model Summary Results and Discussion Conclusions and Recommendations Boom Load Modeling Three-dimensional Modeling Using Orcaflex Environmental Loads Structural Model Resulting Forces Optimizing Skirt and Ballast Weight Summary and Conclusions Boom Concept Refinement Tension Cable Connection Cable Skirt Connectors Buoyancy Elements Costs Summary and Conclusions Station keeping Concepts Concept of Choice Cost Optimization Mooring Configuration Design Considerations Operations Costs Conclusions Platform, Extraction and Transport Debris Collection Rate Calculations Plastic Extraction from Seawater System Requirements Concepts Discarded Design Choices Assessment Final Concept Conclusions Choice of Processing Platform Assessment of Requirements and Possible Solutions Design Alternatives Spar Buoy Concept SWATH Concept Choice of Concept Plastic Transshipment and Transport System Requirements Concepts Discarded Design Choices Assessment Final Concept Conclusions Platform Power Generation Requirements Power Generation Power Storage Results Operations Placement Mooring Installation Boom and Tension Cable Installation Platform Transportation and Installation Installation Costs Maintenance Types of Maintenance Maintenance Vessel and Cost Prevention and Fighting of Biofouling Introduction to Biofouling Likely Effects on the Array Possible Combat Strategies Conclusions Storms and Impact Storm Conditions Conclusions... 07
9 16 TABLE OF CONTENTS 17 TABLE OF CONTENTS 6. Environmental impacts Introduction Ecology of the Ocean The North Pacific Subtropical Gyre Phytoplankton Phytoplankton Abundance Phytoplankton Bycatch Estimations Zooplankton Zooplankton Abundance Zooplankton Vertical Distribution Diel Vertical Migration (DVM) Zooplankton Bycatch Estimations Reduction of Zooplankton Bycatch by The Ocean Cleanup Array Vertebrates Bycatch Solutions Carbon Footprint Analysis Method Carbon Footprinting Scenarios Calculating the Footprint Results and Analysis Conclusions Preliminary Testing OVERVIEW METHODS Fluid Dynamic Observations Bycatch Observations Motion Observations Conclusions Legal Challenges Plastic ownership Obstruction of sea traffic Legal designation of our platforms Bycatch Transport of processed plastic to shore Proposal for a legal framework for international ocean rehabilitation projects Pyrolysis Tests Test Setup Sample Preparation Results Mass Balance of Pyrolysis Conclusions Financials Capital Expenditures Operating Expenditures Breakeven Costs/Prices Cost Conclusions Conclusions Main Conclusions Recommendations Outlook and Next Steps References Acknowledgements Authors and volunteers Sponsors and collaborators Donations OTHER Acknowledgements Appendices Vertical Distribution Data Multilevel Trawl Manual Wave Scatter Diagram Orcaflex Model Parameters CAD MODEL FOR CFD VERSION 2.0 UPDATES...50 About The Ocean Cleanup Processing of Collected Plastic Debris Collection and Characterization of Representative Plastic Samples Recovery Options for Waste Plastics Sample Collection Sample Analysis Degradation Analysis
10 18 CHAPTER EXECUTIVE SUMMARY EXECUTIVE SUMMARY Boyan Slat Hester Jansen Jan de Sonneville Every year we produce about 00 million tons of plastic, a portion of which enters and accumulates in the oceans. Due to large offshore current systems called gyres, plastic concentrates in certain offshore areas, of which the Great Pacific Garbage Patch between Hawaii and California is the best-known example. The damage to sea life is staggering: at least one million seabirds, and hundreds of thousands of marine mammals die each year due to the pollution. Even worse, the survival of many species, like the Hawaiian Monk Seal and Loggerhead Turtle, is directly jeopardized by plastic debris. Marine species often become entangled in larger debris, leading to injury, illness, suffocation, starvation, and even death (NOAA, 2014). Smaller fragments can be mistaken for food and eaten, causing malnutrition, intestinal blockage and death (Figure 1). When marine animals eat plastic, harmful chemicals move up the food chain. Ingestion of and entanglement in marine debris by marine animals has increased by 40% in the last decade. Furthermore, plastics can transport invasive species and toxic substances over great distances. Figure 1 Albatross with plastic in its stomach. Photo by Chris Jordan The problem does not end there. Marine debris causes an estimated $1.27 billion in fishing and vessel damage annually in the region of the Asia-Pacific Economic Cooperation (APEC) alone. Moreover, the removal of garbage from coastlines costs up to $25,000 per ton of plastic.
11 20 EXECUTIVE SUMMARY 21 EXECUTIVE SUMMARY Plastic Organism Figure 2 Schematic overview of the five rotating currents, called gyres, where floating plastic accumulates Figure A preliminary design of a collection platform (Erwin Zwart Fabrique Computer Graphics) Mean current direction In search of a solution Even if we manage to prevent any more plastic from entering the oceans, the natural loss of plastic from the gyres is slow and likely low; therefore, a cleanup is still necessary. Since the problem gained widespread attention at the beginning of this century, several cleanup concepts have been proposed, each based on vessels with nets essentially, fishing for plastic. Unfortunately, even though the concentration of plastic in these five subtropical gyres is extremely high compared to the rest of the oceans, plastic is still spread over millions of square kilometers. Hence, it would likely take many billions of dollars and thousands of years to clean up such an area using those methods (Moore, 2011). By-catch and emissions would likely be problematic using this approach. Furthermore the ocean is not a particularly friendly place to work. Why move through the oceans, if the oceans can move through you? ABSTRACT The world s oceans are characterized by a system of large-scale rotating currents, called gyres. The ocean systems are constantly moving as a result of the turning of the earth and wind patterns. The five major gyres are the Indian Ocean Gyre, the North Atlantic Gyre, the North Pacific Gyre, the South Atlantic Gyre and the South Pacific Gyre. If the ocean s water is constantly moving according to predictable patterns, so is the plastic pollution. This led to the idea of a passive cleanup : using an Array of floating barriers fixed to the sea bed to catch the debris as it flows past on the natural ocean currents. The concept The Ocean Cleanup Array utilizes long floating barriers which being at an angle capture and concentrate the plastic, making mechanical extraction possible. One of the main advantages of this passive cleanup concept is that it is scalable. Using the natural circulation period of the North Pacific Subtropical Gyre, cleanup duration could be reduced to a minimum of just 5 years. Using a passive collection approach, operational expenses can potentially be very low, making the cleanup more viable. Furthermore, converting the extracted plastic into either energy, oil or new materials could partly cover execution costs. Because no nets would be used, a passive cleanup may well be harmless to the marine ecosystem and could potentially catch particles that are much smaller than what nets could capture. Top view Plastic Figure 4 Simplified and schematic cross-section view of a floating barrier. The blue dots represent plastic particles, while the grey dots represent zooplanktonic organisms. The feasibility study Between April 201 and May 2014, The Ocean Cleanup investigated the technical feasibility and financial viability of plastic pollution; technical feasibility in terms of fluid This feasibility study examines the physical properties of The Ocean Cleanup Array concept. With costs covered dynamics, structural engineering and operations; and describes the preliminary testing that has been performed. by a crowdfunding campaign, a global team of over 100 people, companies and institutes have collaborated to It assesses any possible negative environmental effects produce an in-depth study. and legal consequences. Moreover, the study evaluates the quality of ocean plastics, as well as possible methods to process it including a cost benefit analysis. Finally, the feasibility study outlines recommendations for future work.
12 22 EXECUTIVE SUMMARY 2 EXECUTIVE SUMMARY Figure 5 Initial simulation plastic distribution. The locations Figure 6 Map showing the areas in which the highest concentra- where plastic release begins are visualized in red and purple. tion of plastic debris has been predicted by Maximenko et al., source: Van Sebille, England, & Froyland, , van Sebille et al., 2012 and Lebreton et al., 2012, in green. The highest measured plastic concentration is displayed in blue, while the areas containing favorable seabed conditions are depicted in red. Plastic pollution hotspots in ocean gyres Ocean surface current models were used to identify plastic pollution hotspots and subsequent measurement data identified the North Pacific Subtropical Gyre as the area where this project would have the most impact (Figures 5-6). The Ocean Cleanup conservatively estimates the quantity of floating plastic in the North Pacific accumulation zone at 140 thousand metric tons: 21 thousand tons smaller than 2 cm and 119 thousand tons larger than 2 cm. However, more research is needed to increase the accuracy and reliability of these figures. Sampling of ocean plastic is still limited both spatially and temporally particularly for large (centimeter/meter-sized) plastic items. Determination of location On the basis of ocean current models, ocean depth and measured plastic concentrations, The Ocean Cleanup has chosen 0 N, 18 W as the preliminary coordinates for placement of The Array. Environmental conditions in the North Pacific Gyre Using data from weather buoys and satellite recordings, current, wave and wind conditions were estimated for the area of interest (Figures 7-9). The following values have been used as input parameters for structural engineering and fluid dynamic chapters of the report: waves predominantly derive from the northwest (NW), and to a lesser extent also from the northeast (NE) sector. Waves from the northwest (NW) sector are swells generated in the North Pacific Ocean, and waves from the northeast (NE) sector are sea waves. Over 95% of waves are lower than m. The maximum significant wave height (H s ) is 12.2 m with a 100-year return period. The wind predominantly comes from the northeast to east (NE-E) sectors. A mean current velocity of 14 cm/s has been calculated for the area. Figure 7 Wind from direction rose for NOGAPS reanalysis data Figure 8 Surface layer current rose Figure 9 Significant wave height wave from direction rose
13 24 EXECUTIVE SUMMARY 25 EXECUTIVE SUMMARY Fig 11 Glass jars with filtered water and plastic samples collected under different wind conditions (1 and 15 knots) From left to right: samples from 0-0.5m, 0.5-1m, 1-1.5m, 1.5-2m, 2-2.5m, m, -.5m,.5-4m, 4-4.5m, and 4.5-5m depth. Source: Reisser & Slat 2014, submitted Figure 10 The multi-level trawl, used for sampling plastic concentrations Vertical distribution of plastics The concentration of plastic pollution at various depths is an important consideration. This vertical distribution of plastic debris was measured in the North Atlantic Subtropical Gyre using a specially designed net system capable of sampling down to a given depth. Therefore, a floating barrier depth of 2- m is likely to capture most of the total plastic mass floating at the Great Pacific Garbage Patch. The data also suggests there is a relationship between wind speed and vertical distribution of plastic mass, similar to what was observed by Kukulka, et.al. (2012) for number of plastic particles and wind speed. Figure 12 Mean and standard error of plastic concentration (mass per volume) at different depth intervals (N = 12 trawls). Figure 1 A graphic representation of the dependency between the field efficiency, total Array length and deployment time. To increase field efficiency, either the total Array length or deployment time has to increase. Cleanup time and required Array length The Ocean Cleanup investigated the relation between vertical distribution, a capture efficiency of 79% of mass Array length, deployment time and field efficiency. It follows that to increase field efficiency, either the total Ar- 2 cm) were captured under the modeled conditions. How- was calculated. No micro plastics (particles smaller than ray length or deployment time has to increase. A deployment time of 10 years and an Array length of 100 km was the depth within the top m) are caught. The capturing ever, all medium and large size plastics (irrespective of chosen, resulting in a field efficiency of 40-45%. of large debris prevents the creation of small debris by photo-degradation. Investigating basic principles Computational Fluid Dynamics (CFD) has been used to The velocity of the plastic along the barrier depends on study the catch efficiency, the transport of plastic along the boom angle, but is about 40% of the initial velocity the boom, and the forces acting on the boom (Figure 1). when placed at an angle of 0. Variables such as particle size, density and release depth were taken into account in determining which particles would be caught by or escape underneath the boom. Combining this data with modeled mass distribution and
14 26 EXECUTIVE SUMMARY 27 EXECUTIVE SUMMARY Figure 14 Tension cable impression Figure 15 Effect of a too high-tension force along the boom: in the top image, the boom can follow the shape of the wave, but in the bottom image, the tension force spans the boom in such a way that it remains straight Loads on the boom A boom-and-mooring model was set up in Orcaflex to determine the mid-effective tension (the load on the boom) as function of boom length. Forces were determined for a generic boom with a draft of m, at a significant wave height of 5.5 m, which was set as the maximum operational significant wave height. For boom lengths used in the simulation, the relationship between force and boom length was found to be essentially linear. The tension is higher for the Dyneema-tensioned boom than for the neoprene and steel boom. This is due to its high stiffness compared to other options. The steel boom has neoprene links that lower the stiffness significantly. Although the boom likely would not be entirely manufactured out of Dyneema, its readings were used during the dimensioning of the materials as a conservative estimate. Overtopping Orcaflex also found that if the boom were too long, high tension would prevent the boom from following the waves, resulting in overtopping. This is an undesired effect, because plastic would likely be lost in the process, impacting capture efficiency. As illustrated in Figure 15, the boom can follow the shape of the wave, but in the second image the tension force spans the boom in such a way that it remains straight and waves overtop it. If overtopping is to be avoided, it was found that the maximum length of an individual boom should be 1.4 km. Tension cable concept design The Ocean Cleanup developed a boom design in which the boom and tension cable are separated. This design allows the boom to move with the waves, rather than being restricted by the load-carrying part of the boom regardless of the stiffness of the tension cable. The boom is connected to the tension cable every 60 m, transferring its load to the cable. Furthermore this design allows the boom to move along with the rotational motion of the waves, reducing the forces on the tension cable. The use of a tension cable is also included in a patent application from The Ocean Cleanup. Mooring The mooring systems required for station-keeping the structure are novel due to the unprecedented depths at which they would be placed. Given an average depth of about 4 km, a fiber rope mooring system is the only option available. To ensure durability of the system, chain and wire rope is used at the bottom and top ends. A Stevmanta Vertical Load Anchor (surface area 14 m²) is sufficient to withstand the design loads including the safety factor. A three-line system was chosen for all mooring points. Vryhof Anchors confirmed that with current knowledge, mooring at the given water depths is feasible and installation of all system components can be done from the water surface. The mooring configuration is similar to proven solutions at 2,500 m of water depth. The processing platform The platform design is based on a spar, being a stable, cost-effective and proven hull-type. This design consists of a buffer for the collected plastic in the hull of the spar, with a processing-equipment deck as a topside (Figure 16). The hull has a cylindrical shape with a diameter of 11m and a height of 58m. For the storage of plastic, a volume of,000 m³ is reserved in the hull. Although for transport a volume of 6,000 m³ has been reserved, this includes the added water necessary to pump it from plat- Figure 16 Preliminary design of a classic spar as a processing platform. form to ship. The plastic collection rate will total 65 m³/ day, which means the plastic collected has to be picked up by a ship every 45 days. The main deck features processing equipment, including the top of the mesh conveyor, a shredder for large debris and electrical systems. Additionally, the deck incorporates a workshop and a 50-ton crane to lift spare machinery. Photovoltaic panels mounted on the roof over the main deck will provide the primary power supply. The platform is equipped with a slurry pump to extract small particles, coupled to a centrifugal separator for dewatering purposes. Taking into account a cost of 5 per kg of steel (including construction), and a total weight 2,800 tons of steel, the costs of the platform are an estimated 14 million (excluding equipment and mooring). For transshipment and transport of the collected debris a second slurry pump will be used. The costs to transport the garbage to land have been calculated to be 1 million euro per year, or 0.14 per kg plastic.
15 28 EXECUTIVE SUMMARY 29 EXECUTIVE SUMMARY Trawl net Figure 17 Mooring configuration. Schematic drawing of the planned mooring configuration of the booms and trawls. Environmental impact Because they are effectively neutrally buoyant, both phytoplankton and zooplankton are likely to pass underneath emissions of the entire Ocean Cleanup project are The carbon footprint analysis showed the greenhouse gas the barriers. But even assuming the worst The Ocean million kg of CO 2, depending on the chosen scenario. To Cleanup Array would harvest all the plankton it encounters this would constitute a maximum loss of 10 million only 70-1,400 cars based on an average consumption of put this into perspective, it is equal to the production of kg of planktonic biomass annually. Given the immense driving 20,000 km per year. The calculation of the carbon primary production of the world oceans, it would take footprint revealed that the life-cycle stage Marine Transport has the largest environmental impact. This impact less than 7 seconds to reproduce this amount of biomass. can be reduced by limiting the on-site time of the vessel, With regard to vertebrates, harm caused by the barriers seems unlikely because non-permeable barriers are transportation of more plastic per vessel and per cycle as well as by using a highly energy-efficient vessel. The used, although some bycatch may occur in the near vicinity of the platform s extraction equipment. To prevent the footprint. The use of solar energy reduces the platform s could lead to a longer cycle time and a smaller carbon possible impact on vertebrates, active deterrent techniques could be implemented near the extraction equip- carbon footprint. ment. Figure 18 Copepoda individuals are highlighted in the red circle as observed under the microscope. Figure 19 The Ocean Cleanup volunteers collecting beached plastic for analyses of plastic waste processing options. Photo by Megan Lamson / HWF Proof of concept A first proof-of-concept test performed at the Azores Islands validated the capture and concentration potential polyolefin samples were less degraded than expected. From the degradation tests, it can be concluded that the of a floating barrier with a skirt depth of m, in moderate The degree of degradation of high-density polyethylene environmental conditions. In addition, qualitative data (HDPE) appears particularly mild both when compared to suggested that the barrier does not catch zooplankton studies of accelerated aging under controlled conditions as the net behind the boom appeared to have caught an and when compared to the degradation found for polypropylene (PP) from the same sample origin. equal amount of zooplankton as the net next to the boom (Figure 18). Pyrolysis tests have showed that there is at least one Plastic material analysis and processing options to the companies involved in the testing, the quality of method in which ocean plastic can be reused. According Although the possibility of processing plastic into a the pyrolysis oil obtained from the polyolefin fraction of useable and valuable material does not determine the marine debris is comparable to that obtained as regular feasibility of the Array, a valid question is: What would input in their pyrolysis plants. It appears that the production of marine fuel is more attractive due to its sub- The Ocean Cleanup do with the collected plastic? stantially higher yield of 77% for the target fraction when In order to investigate a representative sample of North compared to the gasoline producing process with a final Pacific Gyre debris, half a ton of plastic was collected on yield of 5% for the gasoline fraction. a remote beach on Hawaii Island. See Figure 19.
16 0 EXECUTIVE SUMMARY 1 EXECUTIVE SUMMARY Legal issues This study also provides a high-level overview of key legal issues that may impact The Ocean Cleanup. First, concerning the question of who owns the plastic in the oceans, there are three different legal constructs in play. As most plastic is unlabeled and degraded before being caught, the owner of the plastic cannot be traced, and therefore salvage is not possible. Laws of abandonment cannot be used, as virtually all the traces, including owner information, are lost in the high seas. This leaves the law of the finds, that is based on the following principles: i) intent of the finding party to establish possession over the property in question; ii) actual possession as in exerting physical control over the property; and iii) a determination that the property has been abandoned by the owner. Based on this law, it is assumed that The Ocean Cleanup can take ownership of the plastic collected in the high seas. Second, because The Array presents a unique situation that poses questions regarding shipping right-of-ways and hazards to shipping traffic, it may have to abide by additional safety regulations from either the flag-state or the International Maritime Organization (IMO). For this feasibility study The Ocean Cleanup assumes that platforms will not be flagged by a state and will thus not be subject to state law. The question remains if the UN would have some jurisdiction over the platforms, either by flagging or otherwise. Third, as the Ocean Cleanup Project has the objective of passive collection of floating plastic waste, it would not qualify as a fishing activity. Therefore it does not fall under the current bycatch laws or the laws addressing taking of endangered migratory species. While assessing that The Ocean Cleanup bycatch will likely be minimal, the mere prospect of bycatch might bring The Ocean Cleanup into the realm of regulatory oversight. Financials The Ocean Cleanup Array is estimated to be times cheaper than conventional cleanup proposals per extracted mass of plastics. In order to extract 70 million kg (or 42%) of garbage from the North Pacific Gyre over 10 years, we calculated a total cost of 17 million euro. In the calculations, a limited lifetime of 10 years is applied instead of a general economic lifetime (for most equipment 20 years). This is because projections indicate the mean amount of plastic mass will decrease with time. Thus, the average mass of plastic that will be collected per year will likely be lower than what has been calculated using the 10-year deployment time. As expected with the passive cleanup concept, capital expenditures outweigh the operating expenditures. The total annual estimated operating expenditures is estimated at five million euro. A break-even cost of 4.5 per kg of plastic collected must be realized in order for The Ocean Cleanup Array to be profitable (Figure 24). This amount falls in the range of beach cleanup costs, estimated to be per kg. This is also less expensive than the plastic-caused damage to the maritime industry in the APEC region. Based on the current estimates of costs and the amount of plastic in the oceans, the costs outweigh the profits generated by high-volume solutions, like incineration or pyrolysis, but it is unknown what the financial prospective would be for mechanical recycling. This should be investigated in a later phase. Figure 20 Estimated initial Base Capital Expenditure in euro 000s Last, a proposal for a legal framework is postulated for international ocean rehabilitation projects. Figure 21 Break-even analysis in price per kg for each Array length in km.
17 2 EXECUTIVE SUMMARY EXECUTIVE SUMMARY Figure 24 Phasing of The Ocean Cleanup project Figure 22 OpEx in relation to CapEx, euro (best-, base-, and worst-case) over ten years. Cost per Kg Looking ahead To address the remaining uncertainties identified in the feasibility study, a second phase of the project is proposed to prepare for implementation. In this phase, The Ocean Cleanup will develop a series of up-scaling tests, working towards a large-scale operational pilot in to 4 years. The scale of these tests will likely range from ~10m at the scale model test (1:1000) to ~10km for the large-scale operational test (1:10). Besides assessing new engineering results in a real-world environment, these tests also serve to uncover any unforeseen interactions between the structure and the environment, while allowing for the practicing of operational procedures. In terms of research, the two essential elements in the second phase of the project are: 1 The in-depth engineering and optimization of the structure; 2 Improving the plastic mass estimate, by taking spatial and temporal variability, as well as measured vertical distribution into account. To be more cost-efficient, The Ocean Cleanup will act as a facilitator of the research, outsourcing most of the fundamental research to institutes, and collaborating with offshore and engineering companies to cover most of the tests costs. Conclusions Based on this collected evidence, it is concluded that The Ocean Cleanup Array is likely a feasible and viable method for large-scale, passive and efficient removal of float- Figure 2 A comparison of cleanup costs per concept per kg ing plastic from the Great Pacific Garbage Patch. However, for this project to be successful in reducing the amount of plastics in the Great Pacific Garbage Patch, it is essential for the influx of new plastic pollution into the oceans to be radically reduced.
18 4 CHAPTER 1.11 INTRODUCTION CHAPTER 1.1 What are the causes and effects of plastic pollution? What are the potential benefits of a cleanup operation? What work has already been done in the field, and why haven t they succeeded? How does The Ocean Cleanup plan to change this? These questions are covered in the first chapter of this feasibility study. THE OCEAN CLEANUP
19 6 CHAPTER CHAPTER 1.1 The Plastic Lifecycle is broken Bonnie Monteleone Bill Cooper Figure 1.1 Plastic debris on Kanapou, Hawaii, USA, 2006 (Courtesy NOAA, Marine Debris Programme) Plastics are highly valued for their light and durable qualities, and are widely used not just in packaging but also in consumer goods, building and construction, electronics, medical supplies, and transportation. Most plastics are made from non-renewable petroleum and natural gas resources, and contain chemical additives that have a significant impact on the environment and human health. Unfortunately, despite efforts to reduce their use and increase recycling, humanity uses increasingly more plastic, and much of it ends up in our oceans. This is not just an eyesore, it is a threat to the world s biodiversity. Plastics do not biodegrade; rather they break down into minute pieces, releasing their chemical additives and masquerading as food to marine life. In fact, in 2011 the United Nations Environment Program listed plastic pollution in oceans as a top priority issue, citing its potential impact on ecosystems and human health A Brief History of PlastiC The end of World War II marked the start of the modern plastic era, or Our plastic age (Thompson, Swan, Moore, & vom Saal, 2009). Derived from oil or gas, plastics possess properties that are ideal for the manufacture of many everyday items: they are light, cheap, flexible, strong, and durable (Thompson et al., 2009). Not surprisingly, global plastic production has grown exponentially. From plastic production rose from 1.5 million tons to 270 million tons per year, an expansion which kept pace with the simultaneous global population growth from 2.7 to over 7 billion (Rochman, Browne, et al., 201). In 2012 alone, 288 million tons of plastic were produced (Plastics Europe, 201), which is approximately the same weight of the entire human biomass (Walpole et al., 2012). Two specific issues are associated with this sharp rise in plastic production: impacts on human health, such as increased risk of cancer and neurological problems (Breast Cancer Foundation 201); and the growing amounts of plastic debris entering the marine environment (United Nations Environment Programme, 201) Plastic in the Oceans Plastics are made of essential polymers, synthetically produced from petroleum, natural gas, or coal, and mixed with a complex blend of chemicals known as additives. These additives have the ability to alter or improve the polymers properties. For example, polyethylene terephthalate, or PET, is the nearly indestructible plastic used to make most containers and bottles. Other common additives include: UV stabilizers, antioxidants, brominated flame-retardants, and bisphenol-a. Some of these chemicals are known endocrine disrupters or carcinogens and can seriously affect the health of organisms. Plastic is unlikely to biodegrade, yet does photo-degrade. However, this requires prolonged exposure to ultra-violet light. Physical abrasion also contributes to its decomposition (A. L. Andrady, Hamid, Hu, & Torikai, 1998; D.K.A. Barnes, Galgani, & Thompson, 2009; Colton Jr., Knapp, & Burns, 1974; Gregory, 1977; Thompson et al., 2004). Still, it can take 400 to 1000 years, and even longer in a marine environment, for plastics and their chemical additives to break down into carbon dioxide, water, and small inorganic molecules in a process called mineralization. THE OCEAN CLEANUP
20 8 CHAPTER CHAPTER Figure 1.2 Pathways of plastic pollution. Plastic enters the ocean from coastal urbanization (1), through rivers (2), from beaches (), and from ships (4). Through currents and wind, plastic gets transported through the ocean or sea (5), finally ending up on coastlines or in a gyre. Heavier-than-water plastics are likely to sink not far from the coast (6), unless the plastic encapsulates air. Possible sinks for the plastic in the gyre include sinking due to loss in buoyancy, ingestion, biodegradation, and natural loss onto coastlines due to currents (7) Breaking the Cycle The discovery of fragmented plastic during plankton Even though the monitoring of plastic debris in the ocean tows of the Sargasso Sea in 1971 led to one of the earliest studies of plastic in the marine environment. Using a as conditions vary across different bodies of water and began over 40 years ago, volumes are difficult to estimate micron surface net trawl, Carpenter and Smith collected small fragments of plastics in 1971, resulting in may be made up of a variety of materials, including glass, over time. However, it is known that while marine debris 2 estimates of the presence of plastic particulates at an rubber and Styrofoam, the majority of it (60% to 80%) is average of,500 pieces and 290 g/km 2 in the western plastic. (EPA, 2011) Sargasso Sea (Carpenter and Smith, 1972). Shortly after, Colton et al., (1974) surveyed the coastal waters from Plastic pollution has two major sources: 80% is estimated to come from land and 20% from shipping, and New England to the Bahamas and confirmed distribution of plastic all along the North Atlantic. These studies have is most commonly the result of the improper disposal been recently updated in two comprehensive studies of of single use plastics and manufacturing materials (Allsopp, Walters, Santillo, & Johnston, 2000; D.K.A. Barnes the North Atlantic gyre (K. L. Law et al., 2010; Moret- Ferguson et al., 2010). Indeed, plastic is found in most et al., 2009). Plastic enters the marine environment via marine and terrestrial habitats, including bays, estuaries, runoff, rivers, beach litter, lost cargo, direct dumping, and coral reefs, lakes and the open oceans. (Rochman et al., episodic events. The ocean is downhill from everywhere; 2014, Wright et al., 201) therefore, plastic waste can be washed down streams and rivers from mountains, hills, and valleys. It can enter waterways via storm drains and runoff. Riverine transport contributes substantially to the proportion of land-originating plastic pollution (Ryan, 2008). Once plastic is in the ocean, wind, currents, and wave more, plastics can transport invasive species and toxic action disperse it both laterally and vertically through substances great distances (D. K. A. Barnes & Fraser, the water column. At the same time, currents and wind 200). tend to concentrate debris into accumulation zones, often referred to as garbage patches. This is a misleading gence zones, where marine species tend to congregate These adverse effects are concentrated in the conver- term, because it evokes images of a large floating plastic and plastic debris tends to collect. (A more detailed review of the scope of the problem is presented in the fol- island, when in reality much of the plastic is in small fragments mixed into the top layer of water (NOAA, 2014). lowing section.) Perhaps the most telling research and modeling of how plastics travel in the ocean is the Ocean Surface Current Simulator (OSCURS). To develop this model, tracking pollution has been limited. Important short-term mitiga- So far progress towards halting the rise of marine plastic devices were released into the North Pacific and their tion strategies include beach cleanup activities, which movements observed over a 12-year period. OSCURS revealed that marine debris would eventually accumulate ocean cleanups on coastal and oceanic regions where are performed on the shorelines of many countries, and in the mid-latitudes after travelling for nearly six years high levels of plastic pollution are affecting many species. around the North Pacific gyre (Arthur, 2009) What is the Problem The long-term solution for this environmental issue involves decreasing plastic waste and creating better dis- Being lightweight, durable, strong, and inexpensive, the very properties that make plastic so useful are also responsible for its large negative impact on marine envi- level. MARPOL 7/78 is the international convention for posal practices on land and at sea, at an international ronments. Today, plastic marine debris is found in oceans the prevention of marine pollution, and prohibits the and sediment worldwide and affects marine life along disposal of plastic from ships anywhere in the world s most of the food chain (Wright, Thompson, & Galloway, oceans. However, its enforcement varies globally, and 201). clearly this regulation effects, at most, only 20% of all plastics entering the seas. Other measures to reduce the Marine species can become entangled in larger debris, detritus of plastics in the environment are ordinances leading to injury, illness, suffocation, starvation, and banning plastic single use items such as plastic bags and even death (NOAA, 2014). Smaller fragments can be polystyrene. mistaken for food and eaten, which can cause malnutrition, blockage and death, as well as provide a pathway for Despite these efforts, the use of plastic worldwide continues to grow. transport of harmful chemicals up the food chain (Teuten, Rowland, Galloway, & Thompson, 2007). Ingestion of and entanglement in marine debris by marine animals has increased by 40% in the last decade (GEF, 2012). Further- 2 Marine debris is defined as any persistent solid material that is manufactured or processed and directly or indirectly, intentionally or unintentionally, disposed of or abandoned into the marine environment. Currently, 29 countries have plastic bag legislation, 14 U.S. states with at least one county ordinance and 26 States with proposed legislation. Hawaii is the first State to ban plastic bags countywide. (Duboise, 2014).
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