Permitting Progress Continues For Tigercat’s Carbonizer

Tigercat’s 6040 carbonizer is a mobile, track-mounted unit designed to transform woody debris into high-quality biochar on-site. It reduces volume by 90% and sequesters 20-30% of the available carbon in the feedstock, while slashing emissions by up to 98% compared to traditional processes.

According to Tigercat’s Carbonizer Product Specialist Matt O’Connor, when Tigercat introduced this machine, it entered a space with no established regulatory framework. “Recognizing that customers need confidence before investing in new equipment, we made a deliberate decision: work together with regulators from day one to build clear, repeatable permitting pathways.”

Early in the process, Tigercat applied to the U.S. Environmental Protection Agency’s Office of Land and Emergency Management for a non-applicability determination under the Clean Air Act (CAA). The key question was straightforward: When the 6040 processes clean, untreated cellulosic biomass (such as forest residues or clean wood debris) to produce biochar, is the wood considered solid waste or a process ingredient?

EPA’s response was clear and favorable: The feedstock is treated as a process ingredient, not discarded material. This determination means the 6040 is not regulated as an Other Solid Waste Incineration (OSWI) unit under CAA Section 129 and does not require a Title V operating permit for clean wood biochar production (provided no other Title V triggers apply).

Key to simplifying the permitting process for the Tigercat 6040 in the U.S. is recognition by government agencies that the wood debris feedstock is a process ingredient, that the process generates very low emissions, and that the 6040 produces a useful product.

Additionally, because the 6040 is a self-propelled, track-mounted vehicle designed for mobility across off road terrain, it is not classified as a stationary source under Clean Air Act Section 111.

The 6040 is also exempt from the Commercial and Industrial Solid Waste Incineration (CISWI) rules (under CAA Section 129 and 40 CFR Part 60, Subparts CCCC and DDDD), which apply to units that combust solid waste at commercial or industrial facilities. By treating clean cellulosic biomass as a process ingredient for biochar production (rather than solid waste), EPA has confirmed that the unit does not fall under CISWI applicability. This aligns with EPA guidance on clean cellulosic biomass used in pyrolysis processes: when the feedstock is clean (no contaminants beyond levels typical of virgin biomass) and the output is a beneficial product like biochar, the process is not considered solid waste incineration. This exemption avoids the stricter emission limits, monitoring, and permitting burdens associated with CISWI units, further simplifying deployment for mobile, low-emission systems like the 6040.

Tigercat followed up by requesting additional guidance to promote consistency across EPA regions and delegated state programs, helping lay the groundwork for a more uniform national approach. Comprehensive Tigercat-funded source testing has also established reliable emission factors for particulate matter, black carbon, and CO2, giving operators and regulators the data required for straightforward compliance. In California—one of the most active wildfire-prevention landscapes—Tigercat has completed successful pilots in Tehama, Lake, and Nevada counties using only clean feedstocks. Regulators have responded positively, with minimal scrutiny under 40 CFR 241.3 and quick California Environmental Quality Act (CEQA) categorical exemptions (Classes 4 and 7) due to the minimal environmental impact of the 6040. In Virginia and Pennsylvania, clean wood operations typically require no additional permits outside nonattainment zones (nonattainment zone is an area that does not meet National Ambient Air Quality Standards for air pollutants). North Carolina, Florida, and Texas are following a similar path to Oregon, with deployments (including municipal collection sites in North Carolina, and ongoing operations in Florida and Texas) showing straightforward permitting for clean wood processing. As Tigercat Industries delivers more 6040 units across the country, it is actively collaborating with state environmental agencies to develop or qualify for general permits specifically designed for mobile carbonizers and to create templated permitting approaches tailored to each state, drawing on lessons from early pilots to build repeatable, predictable frameworks. These efforts aim to reduce variability from one jurisdiction to another and shorten approval timelines for operators. In parallel, Tigercat’s dedicated permit assistance team provides hands-on support—reviewing site plans, preparing documentation, and coordinating with local air districts and regulators so customers can focus on operations rather than paperwork. For those pursuing carbon credits, the assistance team guides operators toward simple, third-party monitoring, reporting, and verification protocols that turn environmental performance into additional revenue. For prospective 6040 buyers, the message is simple and reassuring. The regulatory groundwork has been laid. The EPA’s key determination is in place, including non-applicability under Sections 129 and 111 and exemption from CISWI rules. Several carbonizer operators have proven pilot successes on record with expanding operations in North Carolina, Florida and Texas, and general permit progress in Oregon. Tigercat is engaged in ongoing work to standardize processes state by state.