An interesting use of recycled EPS is a product that looks like wood and can be used for park benches and fence posts. The material costs less than hardwood and can be used instead of woods such as mahogany and teak, which are harvested from rainforests.
Making polystyrene requires petroleum, which is a non-renewable resource. So, recycling polystyrene reduces the amount of oil needed for the manufacturing process. This is not a pure gain, of course, because some energy must still be used to transport and reprocess the material.
The most visible benefit of polystyrene recycling is in the reduction of litter both on land and in the sea. EPS, which is not affected by oxygen, sunlight or water, stays around indefinitely. Municipalities have to spend money to clean it up. That's why a number of cities, including San Francisco and Seattle, have banned EPS in take-out food packaging.
Polystyrene takes up space in landfills, where it will remain for hundreds of years. The industry argues that this is not a real drawback because modern landfills are sealed from moisture and light and are not meant to encourage biodegradation. Even organic material does not break down once it reaches a landfill.
Polystyrene also poses a threat to marine life. As it wears out over time, EPS disintegrates into tiny particles, which look like food to fish and may be eaten. The foam clogs the digestive systems of marine animals, killing them. It's estimated that EPS makes up 60 to 80 percent of marine litter, according to a 2008 review in Environmental Research. Recycling can help reduce the amount that winds up in the sea.
Recycling consumer polystyrene also prevents the material from being burned in backyard fires or burn barrels. Polystyrene can produce toxic chemicals when burned unless efficient incinerators are used.
The benefits and the difficulties of recycling polystyrene are a good example of the complex issues that can arise when we're looking at ways to conserve resources and protect the environment. The solutions, as in the case of recycling polystyrene, are not always easy. But we can't necessarily duck the question by turning to alternative materials, either. For example, the paper cup that holds your take-out coffee is usually plastic-coated and is not recyclable. Nor does it break down in landfills. Even a ceramic cup requires much more energy to produce than a polystyrene one and typically continues to use energy to heat the water needed to wash it. There may be a savings in the long run, but the choice is not as clear as it sometimes seems.