What would modern life be like without plastic? According to the United Nations Environmental Programme, global plastic consumption has gone from 5.5 million tons in the 1950s to 110 million tons in 2009. Where does all this plastic go when we’re done with it?
Today Americans discard about 33.6 million tons of plastic each year, but only 6.5 percent of it is recycled and 7.7 percent is combusted in waste-to-energy facilities, which create electricity or heat from garbage.
The rest ends up in landfills where it may take up to 1,000 years to decompose, and potentially leak pollutants into the soil and water. It’s estimated that there are also 100 millions tons of plastic debris floating around in the oceans threatening the health and safety of marine life.
Relatively little plastic is recycled because there are various types of plastic with different chemical compositions, and recycled plastics can be contaminated by the mixing of types. Plastic waste is also contaminated by materials such as paper and ink. Separating plastics from non-plastics in the recycling process, and different types of plastic from each other is labor-intensive and so far, there has been no easy solution.
Although the Society of Plastic Industries developed seven codes to distinguish types of plastic for recycling, in reality, only two—polyethylene terephthalate (PET, used for synthetic fibers and water bottles) and high density polyethylene (HDPE, used for jugs, bottle caps, water pipes)—are routinely recycled. In more and more cities like New York and Chicago, low-density polyethylene (LDPE) plastic bags are now being recycled too. And increasingly the recycling industry’s use of near‐infrared spectroscopy, which can identify the chemical composition of plastics, is improving the efficiency and speed of plastic recycling.
Plastics that can be recycled are first sorted, shredded and rid of impurities like paper. The shreds are then melted and formed into pellets, which can be made into other products.
AERT in Arkansas, and Virginia-based Trex recycle polyethylene into outdoor decking material, fencing, and doors and windows. Coca Cola is recycling its PET bottles and opened the world’s largest bottle-to-bottle recycling plant in Spartanburg, SC to produce 100 million pounds of recycled plastic each year.
Plastic is made from petroleum or natural gas in a chemical process that combines smaller molecules into a large chainlike molecule, often with other substances added to give it particular qualities. Some, like phthalates and bisphenol A, can have harmful health effects. Plastic production is estimated to use 8 percent of yearly global oil production—both as the raw material and for energy in the manufacturing process. Because plastics embody energy from fossil fuels (and actually have a higher energy value than coal), leaving so much of it in landfills is not only an environmental hazard, it is a huge waste of a valuable resource that could be used to produce electricity, heat, or fuel.
The Plastics Division of the American Chemical Council asked the Earth Institute’s Earth Engineering Center to explore ways of recovering the energy inherent in non-recycled plastics. The resulting report, released in August 2011, determined that the amount of energy contained in the millions of tons of plastic in U.S. landfills is equivalent to 36.7 million tons of coal, 139 million barrels of oil, or 783 billion cubic feet of natural gas. If all this plastic were converted into liquid fuel, it could power all the cars in Los Angeles for a year. And the fact is, there are now technologies that can put all this waste plastic to good use.
The report examined three ways of utilizing non-recycled plastic for energy production: converting plastics directly into liquid fuel, using separated plastics as fuel in special types of power plants, and increasing the amount of garbage burned (currently only 10 percent) in waste-to-energy facilities.
Plastics can be converted into crude oil or other types of liquid fuel through pyrolysis, a high heat process. Agilyx, an Oregon-based company, produces processing systems that convert ground unsorted plastic of all types into synthetic crude oil (which can be refined into ultra-low sulfur diesel, gasoline, or jet fuel), as well as synthetic lubricants and greases, some of which can be made back into plastic. The units are designed to go where the plastic is: municipal waste facilities, waste management companies, and recyclers. The base system can convert 10 tons of plastic into 60 barrels of oil each day for about $60 a barrel; so with oil currently selling at around $99 a barrel, it’s definitely cost-effective.
Kevin DeWhitt, chief technology officer for Agilyx, explained that the byproducts of the process include ground-up solids—carbon, small amounts of metal and silicon—that can be sold to the steel, asphalt and cement industries; light gasses that Agilyx can burn and use as heat in its own process; and small amounts of chlorine from PVC (polyvinyl chloride plastic) that are scrubbed out in water and become nontoxic salt. The technology produces a tiny fraction of the emissions (carbon monoxide, volatile organic compounds and nitrogen oxides) allowed by Oregon’s Department of Environmental Quality. A number of other companies in the U.S., Asia and Europe are also producing liquid fuel from plastic wastes.
Power plants specially designed to use plastics as fuel could theoretically produce 1.8 MWh of electricity per ton of waste plastic. Pennsylvania-based EcoClean Burners, Inc. burns plastic pellets (made from unrecycled waste plastic) to create energy for industrial boilers and companies that use steam during the manufacturing process. Based on technology developed in South Korea, the process produces no harmful emissions and uses fuel that is 30 percent cheaper than oil or natural gas.
Burning more garbage in waste-to-energy facilities would recover the energy inherent in plastics and also reduce greenhouse gas emissions since landfills emit methane (a greenhouse gas 20 times more potent than carbon dioxide) as garbage decomposes. Unlike incinerators of the past, modern waste-to-energy facilities produce electricity and heat in boilers designed for complete combustion. The U.S. Environmental Protection Agency has said they produce electricity “with less environmental impact than almost any other source of electricity.” Burning the garbage now sitting in U.S. landfills in waste-to-energy facilities could theoretically yield 162 million MWh of electricity—enough to power 16.2 million households and reduce coal use by 108 million tons.
A 2009 United Nations Environmental Programme report on converting plastic waste into a resource also described the production of gaseous fuels, using high heat to decompose plastic waste, and solid fuel derived from a mixture of waste plastic, paper, and wood. The materials are first shredded, sorted then made into pellets. A number of companies in Japan are producing both solid and gaseous fuels. Currently, the United Nations Environmental Programme – International Environmental Technology Centre is conducting a pilot project in Cebu, Philippines, to convert waste polyethylene (packaging), polypropylene (plastic bags and packaging) and polystyrene (styrofoam, disposable cups,) mixed with waste paper and wood into solid fuel briquettes for use as a coal substitute and fuel to power cement kilns, power plants, industrial heat/steam boilers and stoves.
Also in the Philippines, another ingenious and simple, albeit small-scale, use for discarded plastic involves converting discarded plastic soda bottles into solar bottle bulbs to help light the dark homes of thousands of the poor. Developed by MIT students and inspired by the Appropriate Technology Collaborative, the “bulb” is made from a one-liter soda bottle that is filled with purified water and bleach, then inserted tightly into the roof of a home. The clear water disperses the sunlight and functions like an electric light bulb at a cost of 2 to 3 dollars.
The best solutions for our plastic problem are still to reduce our use of plastics, and to reuse and recycle whenever possible. More policies that ban plastic bag use, require bottle deposits and expand recycling would help. But millions of tons of plastic waste still sit in landfills around the country. What is needed to enable businesses like Agilyx to grow?
“What helps,” said DeWhitt, ”is to streamline the regulatory requirements so that it’s easier for innovative businesses to get off the ground, establish stable government policies to encourage long-term investment, and I’d like to see a production tax credit for this industry.” Technologies that can tap waste plastic as a resource provide multiple benefits: They help clean up the environment, lessen our dependence on foreign oil, decrease our use of non-renewable virgin resources, reduce greenhouse gas emissions, and generate energy.