The world’s largest shipbuilder, Chinese State Shipbuilding Corporation, (CSSC), is announcing plans to harvest some of the oceans 85 trillion tonnes of plastic and recycle it into building materials for its operations. Using a novel approach that involves eddy collection at the ships stern, thus minimizing the drag that would occur if collection was at the bow, the companies method should have an appreciable effect on the global problem of pollution. The Company developed the method in cooperation with Mulliken, Michigan industrial plastic furniture manufacturer PollyProducts whose concern over the problem of plastic pollution led them to develop a simple method for harvesting and refining of the material. State run CSSC will install the collection and refining devices on all of its future projects, such as the cruise ship it is developing for Miami based Carnival Cruise Lines and is developing a model that can be retro fit to many of the larger vessels currently in use.
The device collects plastic flotsam in the stern of the boat before it is carried away by the ships displacement wave where it is churned by the ships propulsion system. Churning allows much of the organic material that exists in the plastic, barnacles, algae, etc. to be returned to the sea. The plastic is then carried by eddy or vortex effect into the collection device where it is shredded into particles as small as 2mm. Pieces of flotsam as large as 1 meter square are thus rendered minute enough to be further processed by the machine. After size reduction several processes, patented by the companies, are employed to separate the plastic by type so it can be rendered into usable material. While not fully explained, the process uses the varied specific gravity of the different types of plastic to sort it by type, i.e. PVC, HDPE, Polystyrene, etc. As well as harvesting the plastic the machinery has the additional benefit of salvaging metals and other materials, such as glass, wood and ceramics contained in the plastic during the process and burns the non-recyclable material, feeding the excess heat back into the ship’s systems. While not a complete answer to the problems of the ocean’s plastic pollution problem, the device is not intended to be used solely for harvesting, but as an adjunct to the ships propulsion system, it is estimated that on a typical transpacific ocean crossing, about 6400 miles, the device could collect over 7 tonnes of material and result in a .04 percent reduction in fuel costs.