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September 24, 2021
EPA considers rulemaking related to pyrolysis and gasification units

On September 8, 2021, the EPA issued an advance notice of proposed rulemaking (ANPRM) and called for public comments in the potential development of regulations for pyrolysis and gasification units that are used to convert solid or semisolid feedstocks into useful products. The feedstocks include solid waste (municipal solid waste, commercial and industrial waste, hospital/medical/infectious waste, sewage sludge, other solid waste), biomass, plastics, tires, and organic contaminants in soils and oily sludge that are converted to energy, fuels, and chemicals commodities.

Pyrolysis and gasification use heat-induced thermal decomposition processes to convert the feedstocks. The key difference in the two processes is that pyrolysis occurs in the absence of air, while gasification occurs in the presence of air.

The Clean Air Act (CAA) does not define pyrolysis or gasification, which has caused the Agency to treat the two processes differently under some CAA Section 129 rules.

“Pyrolysis units have been used for decades in the production of olefins such as ethylene and propylene, and similarly, gasification units have been used for many years in the production of fuel gas from coal,” states the ANPRM. “However, over the past few years, there has been an increase in interest using pyrolysis or gasification units to convert different solid materials, such as agricultural wastes and plastics, into gaseous or liquid fuels or substances or materials to be used in the manufacture of products. Pyrolysis and gasification processes have been touted as potential methods to generate a ‘circular economy’ around plastics use, where a post-consumer plastic product can be recycled to produce a plastic of equal or similar quality again instead of being disposed of or ‘downcycled’ to lesser quality products.”

The EPA is considering this rulemaking because it “believes there is considerable confusion in the regulated community regarding the applicability of CAA section 129 to pyrolysis and gasification units” due to many requests for information it has received for clarification under CAA Section 129 and especially in the different types of language related to pyrolysis in the section.

“On August 31, 2020, the EPA proposed various revisions to section 129 regulations for ‘other solid waste incineration units’ (OSWI), including a proposal to revise the definition of ‘municipal waste combustion (MWC) unit’ to remove the reference to ‘pyrolysis/combustion units’ (85 FR 54178). In the proposal, the EPA indicated that pyrolysis units do not involve the combustion of solid waste but may combust uncontained gases and that the OSWI rule should not apply to such units (85 FR at 54187),” the ANPRM says. “The EPA received significant comments on the proposal regarding the removal of the reference to ‘pyrolysis/combustion units.’”

One of the Agency’s goals during the public comment period is to “gather information on the design, types, and sizes of pyrolysis and gasification units, as well as to identify other issues for consideration, including appropriate categorization of pyrolysis and gasification units.”

Impacted industry includes any utilizing municipal waste combustor (MWC), pyrolysis, or gasification units.