The Word 'Renewable' on Your Gas Bill Is an Accounting Entry, Not a Molecule

In January 2026, Pacific Gas & Electric added a line item to residential gas bills in Northern California: "RNG Program Cost," listed at $0.032 per therm. For an average household using 40 therms per month in winter, that is $1.28. The charge appears right below the standard gas commodity rate, formatted to look routine. There is no asterisk, no explanation box, and no opt-out checkbox.

What PG&E does not explain on the bill is what "renewable" means in this context. The gas molecules flowing through the pipes to that customer's furnace are the same fossil methane they have always been. The "renewable" designation refers to an accounting entry, a certificate purchased from a biogas producer somewhere in the country, possibly thousands of miles away. The customer pays extra. The certificate changes hands. The physical gas does not change at all.

How Book-and-Claim Works

The renewable natural gas market operates on a system called book-and-claim accounting. Under this model, a biogas producer, typically a landfill or large livestock operation with an anaerobic digester, injects gas into the pipeline at one location. A utility hundreds or thousands of miles away purchases the environmental attributes of that gas in the form of a certificate. The utility then claims the renewable designation and passes the cost to ratepayers.

The gas that the customer burns is not physically renewable. It is geologically identical to conventional natural gas. The environmental benefit, if any, accrues at the production site where the biogas was generated. The customer's furnace, stove, and water heater are still burning methane extracted from underground reservoirs.

This is not a secret. The system is described in regulatory filings, academic papers, and even in some utility FAQ pages. But the bill itself presents RNG as if it were a product being delivered. The gap between what consumers reasonably understand and what the system actually does is not an oversight. It is a feature of how the market was designed.

The Cost Premium for an Accounting Entry

Several states now require utilities to procure a percentage of their gas supply from renewable sources. California's SB 1440 established an RNG procurement mandate for gas utilities. Oregon's Climate Protection Program includes natural gas in its cap. Washington's Climate Commitment Act covers gas utility emissions.

These mandates translate directly to bill increases. The American Gas Association estimated in 2023 that achieving a 5% RNG blend would increase residential gas costs by 10% to 25%, depending on regional RNG procurement prices. At higher blend targets, the cost escalation steepens because the supply of low-cost RNG is limited.

Current RNG production costs range from $7 to $30 per MMBtu, compared to $2 to $4 for conventional natural gas. The premium is substantial: customers are paying three to ten times the commodity rate for a certificate, not for a different physical product.

In Oregon, NW Natural's 2024 rate filing included $4.2 million in RNG procurement costs passed through to ratepayers. Divided across the utility's 760,000 customers, that is approximately $5.50 per customer per year at current blend levels. As mandated RNG percentages increase, that figure scales proportionally.

What Consumers Are Not Told

Utility bills are among the most trusted documents in American households. People pay them without reading the details. When a line item says "renewable" or "clean energy," most consumers interpret that as meaning something about the energy they are using. Research from the Energy Policy Institute at the University of Chicago found in a 2022 survey that 67% of consumers believe "renewable natural gas" means the gas in their pipes comes from a renewable source. Only 12% understood the book-and-claim model.

This matters because consumer willingness to pay for climate action depends on trust. If customers believe they are purchasing a low-carbon fuel and are instead purchasing an accounting certificate for gas produced on a farm in another state, the social contract behind green pricing breaks down.

The problem is not that book-and-claim accounting is inherently fraudulent. Carbon offset markets use similar mechanisms. The problem is that utilities are charging consumers a premium under a label that communicates something different from what is actually happening. And unlike voluntary green pricing programs, many of these charges are mandatory.

The Destruction Alternative

The irony is that the methane feeding into the RNG supply chain could be destroyed on-site for a fraction of the cost. An enclosed flare at a dairy or landfill eliminates methane at the source, producing an immediate and measurable climate benefit without any need for pipeline injection, gas cleanup, certificate trading, or utility rate increases.

Destroying methane at a dairy costs roughly $10 to $20 per ton of CO2 equivalent. Processing that same methane into pipeline-quality RNG, transporting it to an injection point, cleaning it to utility specifications, and administering the certificate system costs $50 to $150 per ton of CO2 equivalent. The environmental outcome, methane kept out of the atmosphere, is the same. The cost is three to eight times higher when the gas is monetized instead of destroyed.

For consumers, this means the premium on their gas bill is not buying the cheapest available methane reduction. It is buying the most expensive version, routed through a system designed to keep gas utilities relevant in a decarbonizing economy.

What Honest Labeling Would Look Like

If utility bills accurately described what customers are paying for, the line item would read something like this: "Renewable gas certificate purchased from a biogas producer in another state. The physical gas delivered to your home is conventional natural gas. This charge supports methane capture at the source location."

That description is accurate. It is also unlikely to generate the same consumer acceptance as "RNG Program Cost."

The question is not whether RNG has environmental value at the point of production. Capturing biogas instead of venting it is a genuine climate benefit. The question is whether consumers are being given enough information to evaluate what they are paying for, and whether the system that charges them is the most cost-effective way to achieve the climate outcome everyone claims to want.