The Four Fatal Flaws of Renewable Natural Gas

Avoiding the worst impacts of climate change will require throttling back on fossil fuels. While many electric utilities in the Northwest are beginning to understand that clean, renewable power is their only possible future, the gas utility sector is taking a different tack with a new pipe dream: renewable natural gas (RNG). These utilities aim to position RNG as the answer to decarbonization. It’s an answer that would allow them to continue to grow their customer base, lock in profits from new infrastructure investment, and green up their image. Unfortunately, their RNG strategy rests on faulty assumptions and fuzzy math, plus a bit of deception. In the next article in this series, we’ll explore some of the deceptive tactics utilities are deploying. But first we’ll dive into the fundamentals of RNG.

What is RNG, and where does it come from?

RNG is methane gas, which is chemically identical to fossil natural gas but sourced from decaying feedstocks. Nearly all available RNG is siphoned off landfills, sewage treatment plants, or livestock manure ponds on large industrial farms. These places are rich sources of RNG because when animal waste and trash decay, the microbes that break them down produce gases that contain methane, which can, in turn, be captured, cleaned up, and pumped into a pipeline. Today, many waste facilities already capture their methane gas and use it on-site to generate heat or electricity. Farms also sometimes capture the gas for on-site heat and power, though it is more common for them to release the gas from manure ponds into the air, where it becomes a greenhouse gas in the earth’s atmosphere.

Another flavor of RNG is synthetically manufactured, from either inciting chemical reactions between molecules of water and carbon dioxide or thermal gasification of biomass like crop residues or debris from logging operations. Synthetically produced RNG is still in the early stages of commercialization, as developers have completed only a handful of demonstration projects, and a few larger-scale plants in the European Union are online or in construction.

RNG’s Four Fatal Flaws

On the surface, RNG seems like a promising solution, one with enviable branding: it’s both renewable and natural! But a closer look reveals that RNG is hardly a panacea.

On the surface, RNG seems like a promising solution, one with enviable branding: it’s both renewable and natural! But a closer look reveals that RNG is hardly a panacea.

RNG may play a niche role for a few select purposes, but large-scale RNG deployment would not allow us to maintain business as usual while decarbonizing. RNG has four fatal flaws: availability, cost, carbon intensity, and industry obfuscation.

Fatal flaw 1: Availability

There simply isn’t enough RNG to replace our current consumption of natural gas—not even close. In 2019, gas usage in Idaho, Oregon, and Washington totaled 710 million of the 27 billion BTUs of gas consumed throughout the United States. These quantities far outstrip even the rosiest projections for RNG development. Industry-influenced studies by ICF estimate that RNG could fill in as much as 16 percent of current gas usage nationwide, if all sources were developed. Unfortunately that’s only about half of what’s currently used by the hard-to-decarbonize industrial sector, which accounts for 30 percent of the nation’s gas consumption. (In Cascadia, industry uses a somewhat smaller proportion of the total amount of gas used: 32 percent in Idaho, 24 percent in Washington, and 20 percent in Oregon.) To the extent that any RNG is commercially available, it should probably be reserved for industries that cannot easily replace gas with electricity and have no other cost-effective alternatives for decarbonizing. In fact, studies by Energy Transitions Commission and Rocky Mountain Institute suggest that using RNG for residential or commercial purposes would be misallocating a “precious” resource because these sectors can be transitioned to clean, all-electric power relatively easily.

Fatal flaw 2: Cost

RNG is very expensive relative to other energy sources. Today, a million BTUs (MMBTU) of natural gas costs $3.67. According to a 2019 study prepared for the American Gas Foundation, about 44 percent of prospective RNG projects can be developed at a cost of $7 to $20 per MMBTU, with a median cost of approximately $18. The remaining 56 percent  of potential projects exceed $20 per MMBTU. Many of the lowest-cost RNG projects (those developed from waste streams that are large, centrally contained, and conveniently located near existing pipelines) have for the most part already been developed. What remains are the costlier projects: smaller facilities farther away from pipelines, and biomass that is dispersed and therefore costly to gather and process. Even if we were to replace fossil gas with RNG and continued to use combustion appliances, they would cost a mint to operate. Monthly bills could easily increase fivefold. It would not take too many months of sky-high bills to justify replacing gas equipment with efficient electric alternatives.

Fatal flaw 3: Carbon intensity

RNG has a big carbon footprint. All told, the emissions from natural gas account for nearly a quarter of greenhouse gas emissions nationwide. A clean fuel it is not. RNG is chemically identical to conventional natural gas, which means that it, too, is largely composed of greenhouse gases. It travels through the same leaky distribution pipelines as conventional natural gas, sending small amounts of super-warming methane into the atmosphere. And when RNG is burned in our appliances, it produces the same exact amount of carbon that conventional natural gas does.

The emissions savings from RNG, such as they are, come from preventing the release of the “renewable” methane from decaying feedstock sources like landfills, sewage, and manure lagoons. Yet alternatives to generating this methane in the first place abound, and there is a risk that commercializing RNG could actually increase its environmental impacts. According to a report by California Climate and Agriculture Network, a profitable market for manure-based RNG likely increases localized pollution by reinforcing industrial livestock farming practices that result in liquid-based manure storage and crowded feedlots. If farms pasture-raised their livestock, they could avoid generating much of the methane to begin with. Similarly, diverting landfill-bound waste to recyclers or composting facilities or simply curtailing sources of trash could significantly decrease methane production in landfills.

In all fairness, a full accounting of the emissions from substituting RNG for conventional natural gas or diesel shows that it results in a net decrease. In fact, all told, emissions from RNG are likely to be 55 to 60 percent of conventional natural gas when it is sourced from a landfill or sewage treatment plant, as is most common. Therefore, it may make sense to substitute RNG for natural gas where a net-zero carbon solution doesn’t exist (as is the case for some industrial processes), but from a decarbonization perspective, it does not make sense to use RNG where gas could be simply replaced with net-carbon zero electricity.

Fatal flaw 4: Industry obfuscation

The gas industry is using RNG to greenwash its image while obscuring its real objective: growth at climate’s expense. By marketing RNG as a “renewable” solution to greenhouse gas emissions, the gas industry is drumming up excitement for a product it cannot deliver. The industry aims to create the illusion that our gas system can be decarbonized by introducing a new fuel that can offset today’s gas demand, when in reality, it would offset only a small portion of that demand. If the public buys the pitch, it will enable gas companies to invest millions more dollars into new infrastructure that would lock in decades of profits. The result would be consumers paying higher prices for a façade of greenhouse gas reductions.

The tall tales about RNG don’t stand up to scrutiny. Although there may be some modest climate benefit for a few niche applications like heavy industry, RNG cannot be a replacement for the way we use natural gas now. There isn’t enough of it, it’s too expensive, and it’s bad for the climate. Worse yet, it lets the industry get away with spinning yarns that will benefit gas company’s bottom lines at everyone’s expense. In a follow-up piece, we’ll take a closer look at the tactics Cascadia’s gas industry is using to weave these pipe dreams.