If all the plastics currently put into landfills in the United States were instead converted by pyrolysis to fuel oil, it would add 87 million barrels of oil per year to the U.S oil supply — or roughly the amount of oil the U.S. consumes in 41/2 days.
Several firms — including Envion Inc., Climax Global Energy, Agilyx Corp. and JBI Inc. — are working on, or have developed, processes to pyrolyze plastics into synthetic fuels, according to a study done by the Earth Engineering Center of Columbia University for the American Chemistry Council of Washington.
The study also said if that same amount of plastics were used as fuel in power plants designed to use plastics, it would produce enough electricity, 52 million megawatt-hours, to power 5.2 million households annually.
According to the report, about 57.6 billion tons of post-consumer plastics, or 85.8 percent of all plastic used in the U.S. in 2008, was landfilled, 7.7 percent was combusted with energy recovery and 6.5 percent was recycled.
The report, published in mid-August, found that if all municipal solid wastes were diverted from landfills to new waste-to-energy power plants, it would produce 162 million megawatt-hours of electricity, enough to power 16.2 million households for a year.
“Landfilling of [non-recycled plastics] constitutes a loss of a valuable energy resource,” said the report.
Marco Castaldi, associate director of the Earth Engineering Center, agreed.
“Capturing the energy value of non-recycled plastics — and municipal solid waste in general — makes good sense because it provides a good domestic form of energy while minimizing impacts on the environment,” he said.
One example: The diversion of just 25 percent of mixed biomass and non-recycled plastics in municipal solid wastes to waste-to-energy plants would cut greenhouse gas emissions by 35 million to 70 million tons of carbon-dioxide equivalent, depending on the degree of capture in present landfills, the study said.
Also, it said, states with the most waste-to-energy capacity — Connecticut, Massachusetts, Hawaii, Maine, Virginia, and Minnesota — recycle, or reuse as energy, between 32 percent and 65 percent of plastics that are discarded annually.
The report said another way to recover the energy value of non-recycled plastics is to boost the capacity and number of U.S. waste-to-energy plants, now around 87. Most plastics made in the U.S. are made from natural gas, not petroleum.
“As the United States seeks alternative fuel sources, projects like this — which help quantify the scale and availability of an energy source — are crucial to helping identify renewable fuel sources for policy makers,” said center director Nickolas Themelis.