November 12, 2024

Clean Cellulosic Biomass and NHSM Determinations

40 CFR Part 241 establishes procedures for identifying solid wastes used as fuels in combustion units regulated under RCRA and the CAA. “Nonhazardous secondary materials” (NHSMs) are typically solid wastes when combusted unless they meet specific criteria in Part 241. One of these provisions states alternative fuels, such as clean cellulosic biomass, are fuels and are not secondary materials or solid wastes unless discarded. Below are excerpts from EPA’s RO 51463, which provides guidance on clean cellulosic biomass.

What is clean cellulosic biomass?

Clean cellulosic biomass consists of residuals equivalent to traditional cellulosic biomass (i.e., harvested plant-derived organic matter) and is considered “clean” when it contains contaminants at concentrations no higher than those normally associated with virgin biomass materials. Examples include tree trimmings, sawdust, wood pellets, tree stumps, corn stover, peanut shells, cotton byproducts, clean wood found in disaster debris, and clean construction and demolition (C&D) wood.

Are units that combust clean cellulosic biomass as fuel regulated as solid waste incinerators under the CAA?

No. Units burning this material as fuel would not be regulated as solid waste incinerators under CAA Section 129. However, these units may be subject to CAA Sections 111 or 112.

What does “unless discarded” mean in the context of clean cellulosic biomass?

Generally, cellulosic biomass managed separately from solid waste and to be burned for energy recovery would not be considered “discarded.” On the other hand, cellulosic biomass that has been mixed with solid waste or that has been disposed of (e.g., landfilled) would be considered “discarded.” Units combusting these co-mingled materials would be regulated as solid waste incinerators unless the material is sufficiently processed and meets the legitimacy criteria for non-waste fuel in Part 241.

How does C&D debris relate to the definition of clean cellulosic biomass?

Clean C&D wood is considered clean cellulosic biomass, while C&D debris, which consists of a mixture of material resulting from C&D activities, is not. C&D debris may be processed to produce C&D wood to meet the definition of clean cellulosic biomass. [§241.4(a)(5)]

What is the status of biomass that has been combined with municipal solid waste?

Biomass combined with municipal solid waste or other types of solid waste has been discarded. A unit combusting such a mixture would be regulated under CAA Section 129, unless the combined material is first adequately processed and meets the legitimacy criteria of §241.3(d) as a non-waste fuel. More information on non-waste fuel determinations is available in 2021’s NHSM Guide for Waste/Non-Waste Determinations.

What is the status of clean cellulosic biomass processed to make biochar?

Clean cellulosic biomass processed to make a biochar product using pyrolysis or a similar process would not be considered discarded, a secondary material, or solid waste under the CAA. Such biochar is considered a “traditional product.”

What is the status of biomass that does not meet the definition of clean cellulosic biomass?

Biomass that is not “clean cellulosic biomass,” such as treated wood, is a solid waste when combusted as fuel unless it has been sufficiently processed and meets the legitimacy criteria for non-waste fuel in §241.3(d)(1) or meets one of the categorical non-waste fuel listings in §241.4. Additionally, biomass that is not clean cellulosic biomass is considered discarded when used in a combustion unit to make biochar unless it meets the legitimacy criteria for a non-waste ingredient in §241.3(d)(2).

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This document addresses issues of a general nature related to the federal environmental regulations. Persons evaluating specific circumstances dealing with the environmental regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.