Complying with the California LCFS: How Greentruth Builds a Pathway-Ready Audit Trail

LCFS compliance is the operational and documentation work that separates a certified, verifier-defensible fuel pathway from one that gets pushed back at the CARB review stage. California's Low Carbon Fuel Standard rewards low-carbon-intensity fuels with credits — but only when the pathway behind the CI score holds up to mass-balance scrutiny and accredited third-party verification. This page lays out the regulatory architecture, the operational stack pathway holders have to assemble, and how Greentruth's QET-RNG with the QET-LCFS extension produces a pathway-ready audit trail.

LCFS compliance, in one paragraph. California's Low Carbon Fuel Standard (administered by the California Air Resources Board, CARB) requires fuel pathway holders to certify a carbon intensity (CI) score for each low-carbon fuel they supply, maintain mass-balance chain of custody from production through dispensing, and undergo accredited third-party verification. The operative modeling tool is CA-GREET 3.0. Greentruth's QET-RNG with the QET-LCFS extension produces the chain-of-custody record, CI inputs, and verifier-ready documentation a CARB pathway team and accredited verifier expect.

For transportation buyers specifically

The Low Carbon Fuel Standard, codified at CCR Title 17 §95480 et seq., requires the California fuel pool to reduce its average carbon intensity over time. Each fuel certified under the program receives a CI score (in gCO₂e/MJ); fuels below the annual benchmark generate LCFS credits, and fuels above it generate deficits. Credits and deficits trade in a market overseen by CARB. For pathway holders, the practical work is threefold:

• Certify the CI score for the specific pathway under one of CARB's pathway tiers.
• Maintain mass-balance chain of custody between the certified pathway and the volumes claimed against it.
• Undergo annual third-party verification by a CARB-accredited verifier.

The third leg — verification — is where pathway integrity is most often tested. Biomethane (RNG) pathways with negative CI scores attract particular scrutiny: the more favorable the CI, the closer the verifier looks at every assumption, every measurement, and every documentation gap.

For the foundational QET overview

LCFS compliance work reaches several roles, each with a different documentation responsibility:

• Fuel pathway holders. Producers and aggregators who hold one or more certified pathways. They carry the largest documentation load — pathway application, quarterly reporting, annual verification, and ongoing operational records.
• Producers and processors of biomethane. Specifically for RNG-based pathways (landfill gas, dairy digester, food-waste digester, wastewater), the upstream measurement program at the producer is the foundation of the CI score.
• Blenders, terminals, and pipeline injectors. Where the certified fuel enters the supply chain that the pathway documents.
• Fleet operators and fuel dispensers. Where the certified fuel is consumed, and where the dispensing event is recorded.
• Regulated parties (obligated parties under the LCFS). Refiners and importers of gasoline and diesel who carry deficits and need credits to offset them.

A buyer that takes physical delivery of RNG into a pipeline system and dispenses it as a transportation fuel is implicitly engaging the entire stack — and the audit trail has to follow the molecules through every operator involved.

For mass-balance chain-of-custody in detail

For most RNG pathways with non-trivial CI claims — and especially for negative-CI biomethane pathways — Tier 2 is the operative tier. The implications are real: Tier 2 pathway certification typically requires a full custom CA-GREET 3.0 model, supporting documentation on feedstock sourcing and counterfactual emissions, and an extended CARB review cycle before certification is granted.

A QET-RNG with the QET-LCFS extension is structured to feed a Tier 2 application directly, with the chain-of-custody record and producer-side measurement program already documented at the level CARB asks for.

The CI score on a certified LCFS pathway is the output of a specific modeling stack. Pathway holders have to assemble inputs at each layer:

• CA-GREET 3.0. California's adaptation of Argonne National Laboratory's GREET model, modified for the regulatory context of the LCFS. CA-GREET 3.0 is the operative tool for Tier 2 pathway CI calculations.
• Site-specific production data. Volumes, feedstock characteristics, energy inputs, captured/avoided methane (for digester pathways), and process emissions at the production facility.
• Transportation and distribution data. From production to injection point, and across the pipeline system to dispensing — the part of the CI score most often defaulted to averages and most often defensible only as deep as the chain-of-custody documentation goes.
• Counterfactual emissions (where applicable). For pathways relying on avoided methane (landfill, dairy), the counterfactual emission scenario the avoided methane is measured against.
• Indirect effects and additive deductions. Where applicable under the methodology in force.

The pattern that comes through: the CI score is only as defensible as the inputs it consumes. Site-specific primary data tightens the CI score and makes the verification cycle shorter; default values widen it and lengthen verification.

How modeled defaults vs measured values trade off

Mass-balance chain of custody is the operational discipline that ties the certified pathway's volumes to the volumes actually delivered. The LCFS does not require physical commingling avoidance — RNG injected into the natural gas system necessarily commingles — but it does require a documented mass-balance accounting that closes the books on volumes injected vs volumes claimed at dispensing. For RNG pathways specifically, mass balance means recording five elements per delivery:

• Injection point identified. The physical point at which the RNG entered the natural gas system.
• Customer delivery point identified. The physical point at which the dispenser (or buyer) takes delivery.
• Pipeline connectivity confirmed. A valid physical path between injection and delivery.
• Volumetric equivalence established. The volume injected equals the volume claimed on a mass-balance basis.
• Temporal matching confirmed. The injection and delivery are matched within the reporting period.

These five criteria are not a Greentruth invention — they are the operational shape mass-balance chain of custody takes under the program, and they are the criteria CARB verifiers most reliably ask about. They are also the criteria a QET-RNG thermal certificate validates against before it can issue.

How biogenic CO₂ is preserved in the carve-out

A QET-RNG with the QET-LCFS extension is structured so that the LCFS audit trail is a byproduct of operations rather than a discrete compliance project. The extension layers LCFS-specific elements on top of the core QET-RNG methodology — including CA-GREET 3.0 inputs where required — without rebuilding the underlying record. What the token carries that matters for LCFS compliance:

• Pathway-level provenance. Producer, feedstock category, production facility, and certified pathway identifier.
• Site-specific production data. Volumetric, feedstock, and process measurements at the producer, recorded at the methodology's data hierarchy tier.
• Verified carbon intensity. kgCO₂e/MMBtu using IPCC AR5 GWP100 (CH₄ = 28, N₂O = 265), with separate biogenic carve-out preserved per the GHG Protocol biogenic guidance.
• Mass-balance evidence. All five thermal-certificate verification criteria — injection point, customer delivery point, pipeline connectivity, volumetric equivalence, temporal matching — recorded on the token.
• Methodology version and verifier of record. ISO 14064-3 reasonable-assurance verification by an accredited third party, stamped on the certificate.
• Verifier-ready export package. PDF and JSON outputs structured for the CARB pathway team and the accredited verifier's annual review.

The result is that a producer's pathway application and a verifier's annual review draw from the same record — one set of documents, two audiences.

For the full QET-RNG concept page

For the long-form methodology

How retirement anchors the LCFS claim

Several low-carbon-fuel programs run on similar architectures and are increasingly relevant to RNG pathway holders building cross-jurisdictional strategies:

• Oregon Clean Fuels Program (CFP). Administered by Oregon DEQ; structurally similar pathway architecture; same general mass-balance logic.
• Washington Clean Fuel Standard (CFS). Administered by Washington Department of Ecology; phasing in over the next several years on a comparable design.
• Canada Clean Fuel Regulations (CFR). Administered by Environment and Climate Change Canada; covers liquid fossil fuels with its own pathway and CI architecture.

A producer with a certified California pathway typically has most of the underlying operational and chain-of-custody infrastructure needed for these adjacent programs. The QET-RNG with QET-LCFS extension generates records structured to be portable into adjacent program submissions where the underlying methodology is comparable.

For mass-balance chain of custody concept

For migration from legacy registries

How QETs align across reporting frameworks