The plastics industry’s quest to solve the problem of plastic waste through so-called “advanced” recycling—using chemical additives and sometimes extremely high heat to turn waste back into new plastics—is costly and comes with significant environmental impacts, according to new research from the federal government’s National Renewable Energy Lab in Colorado.Get more news about Recycled Plastic Granule,you can vist our website!
Government researchers singled out two prominent “advanced” technologies—pyrolysis and gasification—as particularly problematic, saying they should not even be considered “closed-loop” recycling technologies. These technologies require large amounts of energy and emit significant pollutants and greenhouse gases to turn discarded plastics into oil or fuel, or chemicals such as benzene, toluene and xylene, synthetic gases and a carbon char waste product.
So far, 21 states have enacted laws sought by the U.S. plastics industry that categorize advanced plastics recycling as a manufacturing process and not waste disposal. But environmentalists say using plastic waste to make new fossil fuels or feedstocks for more plastic further damages the environment and worsens climate change.
Other forms of chemical recycling fared better than pyrolysis and gasification in the new research, but the more traditional method of recycling—using mechanical means to sort, clean, shred and remold waste plastic—performed better on economic and environmental parameters than emerging methods, although it still has technical limitations, the researchers found. Taken together, the peer-reviewed study by a 12-member Department of Energy team that examined the benefits and trade-offs of current and emerging technologies for recycling illustrates the major challenges ahead as the world seeks ways to handle the 400 million metric tons of plastic waste generated globally each year.
Mankind is producing twice as much plastic waste as two decades ago, with the bulk of it dumped in landfills, burned by incinerators or littered across the environment, with only 9 percent recycled, according to a report last year from the Organization for Economic Cooperation and Development, a group that represents developed nations.
“There’s a lot of work around plastics and it’s very much a hot topic,” said research analyst Taylor Uekert, the lead author of the new study, “Technical, Economic, and Environmental Comparison of Closed-Loop Recycling Technologies for Common Plastics,” published Jan. 12 in the American Chemical Society’s peer-reviewed journal, Sustainable Chemistry & Engineering. “The inspiration here was really to look at all of these different up-and-coming recycling technologies and figure out how they stack up on a consistent basis on environmental, economic and technical perspectives.”
Experts say plastic was never designed to be recycled. It is made of polymer chains and chemical additives, many of them toxic, meant to give the material different properties, such as flexibility, texture, clarity and color. The varied chemical nature of plastic waste, much of which gets mixed together after it is used once for a few minutes, only adds to the challenge of recycling.
The researchers studied several kinds of chemical recycling, focusing on those that could legitimately be considered “closed loop” solutions, in which plastic waste is turned into feedstock to make new plastics.
Among those were technologies that use solvents, enzymes, acids or methanol to break down plastic into its chemical building blocks. They also examined different kinds of plastics, including high- and low-density polyethylene (HDPE and LDPE), polyethylene terephthalate (PET), and polypropylene (PP).
With the exception of mechanical recycling, the technologies that the team evaluated are mostly in early development, including some with pilot projects, Uekert said.
The chemical industry has been pushing for regulatory changes at the state and federal level that would encourage pyrolysis or gasification or relax clean-air requirements. The Environmental Protection Agency describes pyrolysis and gasification as heat-induced thermal decomposition processes, although gasification uses some oxygen.
Some industry proposals have faced strong pushback locally and from national environmental groups, including a troubled new chemical recycling plant in Ashley, Indiana, a proposed plant in Point Township, Pennsylvania, and a proposed trash-and-plastic waste-to-jet fuel plant in Gary, Indiana.
U.N. diplomats are also debating the role of chemical recycling as part of an existing hazardous waste treaty, with implications for a proposed global treaty on plastic waste, as the chemical industry lobbies for chemical recycling as part of a “circular economy,” another term for closed loop.
But when it comes to pyrolysis and gasification, each dependent upon a lot of energy and heat, the NREL researchers did not even consider them to be closed-loop solutions since typically they turn plastics into fuel or other chemical feedstocks, not new plastic.
