Developing new uses for ocean plastic

In 1972, Scarp was abandoned. Owners of a few holiday homes use the island only during summer. People continue to use beachcombed items for decorative and practical purposes in Harris and the Hebrides. On fences and gateposts, you will find buoys and trawler floats. PVC black pipe is used to drain footpaths or as fence posts. It’s easy to find in abundance from the fish farms that were destroyed by storms. Splitting larger pipe lengthways can make feeder troughs to feed the hardy highland cows.

Lorna Wheeler created a birdfeeder from plastic waste that washed up on the shore at the Handmade Harris Craft Market in Tarbert. Ian Lambert, the Author, provided

Rope and nets are used to block wind or prevent erosion. For storage, many islanders use large plastic crates that wash up on the shore – fish boxes. There is also a small industry that recycles plastic waste into tourist souvenirs. This includes everything from bird feeders and buttons to button necklaces.

This beachcombing and recycling of large plastic items is only a small part of the solution. Smaller fragments of plastic, which are harder to collect, are more likely than larger ones to be absorbed into the food chain or drawn back to the sea. Plastic geology is often revealed by storms that cut away riverbanks. Layers of plastic are found in the soil several feet down.

In the last ten years, reports on the extent of plastic pollution in the oceans of the world have been widely reported. The final episode of BBC’s Blue Planet II with David Attenborough in 2017 marked a turning point in public awareness of the issue. The amount of plastic that enters the oceans every year is estimated to range between 8m tons and 12m tonnes. However, there are no accurate measurements.

The problem is not new: one islander who spent 35 years on Scarp reported that the number of items found on Mol Mor has decreased since New York City ceased dumping garbage at sea back in 1994. The BBC Radio 4 program Costing the Earth reported that litter on beaches has doubled since 1994.

New methods for old problems

A growing awareness of ocean waste has prompted local efforts to clean up beaches. The amount of garbage collected raises the question: What is to be done? Ocean plastic degrades with prolonged exposure to sunlight. This can make it difficult to identify and recycle, as it’s contaminated with sea life and salt. Some recycling methods are only successful with a ratio of 10 % ocean plastic and 90 % plastic from domestic sources.

Local groups often work together to collect large quantities of plastic on the beaches. But for local authorities, the challenge is to figure out how to handle a material that’s difficult or impossible to recycle. The alternative is to landfill, which charges PS80 per tonne. The lecturer and jeweler, Kathy Vones, and I investigated the potential of reusing ocean plastic as raw material for 3D Printers known as Filament.

Polypropylene can be ground and shaped easily, but it must be mixed 50/50 with polylactide to achieve the consistency required by the printer. This is a step in the wrong direction, as it makes recycling plastics more difficult. However, by experimenting with new uses, we can make two big steps forward. Polyethylene terephthalate, high-density plastics (HDPE), and other ocean plastics are also suitable.

Another method I considered was to melt the polypropylene over a fire and then use it as an improvised machine for injection molding. This technique was not able to maintain the right temperature and produced toxic fumes.

Design for an off-grid, bonfire-powered, foraged-plastic-fuelled injection molding machine. Ian Lambert is the Author.

Boyan Slat, the Dutch inventor behind the Ocean Clean Up Project, was much more ambitious. He aimed to collect 50% of the Great Pacific Garbage patch in five years using a large net suspended on an inflatable boom, which catches and pulls the plastic into a platform for collection. Has encountered difficulties and, in any event, will only collect larger fragments on the surface. The majority of oceanic plastic is smaller particles than 1mm and suspended within the water column. More plastic also sinks to the ocean bottom.

They will need new solutions. The removal of huge quantities of plastic from the environment will be a problem for many centuries. Politicians and industry need to work together and come up with new ideas.