Design of a Marine Debris Removal System

The amount of human generated debris entering the oceans was recorded at eight billion kilograms (kg) in 2010, and has been rising exponentially by 10% each year. The most common pollutant is plastic which composes about 80% of the debris. Plastic takes approximately 500 years to decompose, and in that time, it is harming wildlife while collecting in the ocean's circular currents called gyres. The Subtropical Convergence Zone, stretching between California and China, contains the largest of the five major gyres, the North Pacific Subtropical Gyre, which is located between California and Hawaii. The estimated cost of environmental damage from human generated debris is about three billion dollars. Seven design alternatives are evaluated: autonomous vacuum (AV), vessel with nets (VN), barge with unmanned aerial vehicles (B-UAV), artificial floating island (AFI), artificial floating island with sail (AFI-S), artificial floating island with motor (AFI-M), and barge with autonomous surface vehicles (B-ASV). Using a multi-attribute utility function, the best alternative was determined per weights associated with performance, technology readiness level (TRL), and risk. The design alternatives are ranked as follows: AV at 8.461, AFI-M at 7.188, AFI-S at 6.849, B-UAV at 6.571, AFI at 6.221, VN at 4.288, and B-ASV at 2.287. The weight that significantly changes the value of the design alternatives is performance. With a change in the weighs, the optimal solution changes from the AV to the AFI-M. The most viable option is the AV; one AV would clean up the Subtropical Convergence Zone in approximately 5700 years while 5700 AVs would clean up the debris in one year.