EPA’s move to redefine pyrolysis sparks debate over chemical recycling regulation

The US Environmental Protection Agency’s effort to strip pyrolysis from a key air emissions rule has become a flashpoint in the wider fight over chemical recycling, exposing both the political support now building around the sector and the continuing resistance from environmental groups and some state regulators.

At issue is an EPA proposal to clarify that certain pyrolysis technologies used for chemical recycling are not forms of incineration under the Clean Air Act. That would remove the reference to “pyrolysis/combustion units” from the agency’s definition of a municipal waste combustion unit under its Other Solid Waste Incinerators category, effectively taking those facilities out of the current OSWI framework.

The public comment period on the plan closed on May 4 after drawing hundreds of submissions. According to the EPA, the exercise is intended to help shape future regulation of pyrolysis and gasification units, but the agency has not yet said what happens next.

The proposal lands as the Trump administration’s EPA has moved to present advanced, or molecular, recycling as part of a broader industrial and economic strategy. In an April 24 op-ed in The Hill, Administrator Lee Zeldin said the sector is being constrained by regulatory uncertainty and argued that the current classification of pyrolysis as incineration does not reflect how the technology works. The EPA has also said it wants to hear from stakeholders as it develops a future framework for these units.

Supporters of the change, including companies and trade groups tied to plastics and agriculture, say the current regime is too vague and is deterring investment in a technology they view as manufacturing rather than waste disposal. LyondellBasell told the EPA that treating pyrolysis like combustion “does not reflect how they operate and creates unnecessary barriers to growth and innovation”. The company said the change would make it easier to permit future projects, including a possible commercial-scale pyrolysis plant in Houston.

The industry’s argument is that pyrolysis uses heat in an oxygen-starved environment to break down feedstock rather than burn it. Proponents say that distinction matters for permitting, finance and scale-up, particularly in a US market where there are still fewer than 10 chemical recycling facilities.

Zeldin has also framed the issue as one of international competitiveness. In his op-ed, he said Europe and Asia are moving faster on advanced recycling and warned that the US could fall behind if it does not scale the technology. The EPA chief also pointed to a patchwork of state laws: about 25 states classify chemical recycling as manufacturing, while others leave it within solid waste rules. A separate bill in Congress, the Recycling Technology Innovation Act, would also define chemical recycling as manufacturing.

Critics say the push would weaken oversight rather than clarify it. Environmental groups argue that moving pyrolysis out of the OSWI rule would allow operators to avoid stronger air pollution controls and reporting requirements. The Ocean Conservancy told the EPA that pyrolysis units are not truly oxygen-free and therefore still involve oxidation, which it argued means they fall within the definition of solid waste incineration. Beyond Plastics’ Judith Enck said in an email that no other section of the Clean Air Act adequately regulates the facilities and warned that the change would let pyrolysis units avoid safeguards designed to protect nearby communities.

Several opponents also objected to the length and framing of the consultation. The 45-day comment period, they said, was too short for such a technically complex issue. The Ocean Conservancy called the process misleading, while Global Alliance for Incinerator Alternatives and Beyond Plastics asked the EPA to extend the timetable. Beyond Plastics also criticised the fact that the pyrolysis language was embedded in a broader proposal dealing with air curtain incinerators and disaster debris.

Local government and industry stakeholders have backed the EPA’s move. Kent County, Wisconsin, which operates a waste-to-energy facility and uses pyrolysis to make biochar, said the technology should not be treated as incineration. Director Darwin Baas said the biochar can replace cement or be used as an asphalt additive, helping reduce landfill use and methane emissions. The Ag Container Recycling Council made a similar case, arguing that chemical recycling offers one of the few practical routes for harder-to-recycle agricultural plastics and containers.

State regulators, however, have urged caution. Oregon’s Department of Environmental Quality said removing pyrolysis from the combustion definition would create a gap in emissions tracking and permitting, and warned of potential harm to both public health and the environment. It said the EPA should wait until separate standards are in place before changing the rule.

The policy fight comes as chemical recycling remains a contentious and still relatively small part of the waste and materials landscape. Its backers see it as a route to recover value from plastics that mechanical recycling cannot handle; its critics see a technology whose commercial promise remains overpromised, with too many facilities still facing permitting delays, financing problems, bankruptcies and community opposition.