Don’t be fooled: ‘Renewable natural gas’ is a pipe dream

Gas utilities claim RNG can heat our buildings but not our planet; research says otherwise

A RMI series on building electrification

By Jonny Kocher and Zack Subin

Special to The Examiner

Over the past few years, natural gas companies have attempted to convince us — consumers, politicians and regulators — that the natural gas heating our buildings is “renewable” and even good for the planet. As technical experts on decarbonizing buildings, we are here to tell you: This is not the case.

Millions of Californians rely on methane every day in the form of fossil gas, masquerading under the greenwashed moniker “natural gas.” This gas is composed of 80% methane — a potent greenhouse gas — making the direct emissions from burning gas to heat and cook in buildings a whopping 10% of the state’s total annual greenhouse gas emissions.

This is even more staggering when you realize that methane comes to our buildings from a leaky network of wells and pipes — and just one gram of methane will heat the planet 86 times more than a gram of carbon dioxide over the first 20 years of its atmospheric life. For example, the 2015 Aliso Canyon gas leak spewed climate pollution equivalent to 7 million cars daily at its peak. This is why the UN Environment Programme proclaimed last year that “cutting methane is the strongest lever we have to slow climate change over the next 25 years.”

An umbrella term for three types of fuel

But as lawmakers have started to seek ways to slash gas from the building sector, gas utilities have cooked up a new scheme to make this polluting product more palatable: “renewable” natural gas or RNG. RNG is an umbrella term for three broad types of fuel: biomethane, low-carbon hydrogen and synthetic natural gas. Despite the varieties of fuels available under RNG, all of them have pitfalls that make them impractical for the building sector.

Biomethane is the most cost-effective form of RNG, but there is a limited supply and there are serious doubts as to whether it can actually reduce emissions. Biomethane is captured from sources such as landfills, wastewater treatment plants and livestock; or created through industrial processing of forest and agricultural residue. At best, this could meet 30% of California’s current gas needs, according to high end estimates from a California Energy Commission report on the subject.

A Natural Resources and Defense Council estimate from the gas industry’s own data suggests a much lower amount available. More concerning than its limited supply is evidence that biomethane is only carbon neutral when it comes from preexisting sources, which otherwise would be leaked into the atmosphere. All other biomethane would come from newly created sources of methane, which will increase overall greenhouse gas emissions.

Contrary to overly optimistic claims on the availability of biomethane, gas utilities will increasingly rely on low-carbon hydrogen to reach their climate targets. Green hydrogen — created using renewable electricity — is the simplest to produce.

But the California Energy Commission report observed that existing natural gas pipelines can handle only a maximum of 5% to 7% hydrogen blended with natural gas (by energy content) before costly upgrades to the gas distribution system and end-use appliances are needed. Therefore, hydrogen can be only used in limited amounts in buildings. And it will always be far more efficient to use renewable electricity directly to power heat pumps than to create green hydrogen, pipe it to homes and burn it. For these reasons, recent reviews of green hydrogen potential rate buildings as an unpromising application compared with uses such as substituting for methane gas in creating fertilizer.

This leaves synthetic natural gas, the most energy intensive and costliest of the bunch. Creating synthetic natural gas requires two energy intensive steps: first CO2 needs to be scrubbed from the atmosphere, then it must be combined with green hydrogen to produce methane. In the most optimistic scenario in the California Energy Commission report, researchers predict that synthetic natural gas would cost eight times as much as the projected cost of fossil gas.

Intead of tripling of home utility bills, electrification

Together, biomethane, synthetic natural gas and green hydrogen are so expensive that the average customer living in a home with natural gas appliances would see their utility bills triple from $165 a month currently to over $450 a month by 2050 even when accounting for inflation. Facing high bills, those who can afford it will then switch to electric appliances, leaving low-income customers to bear the brunt of the increasingly costly natural gas infrastructure. The only way to avoid this is a gas transition strategy where the system goes through targeted decommissioning, reducing costs to the utility and to its customers.

Luckily for Californians, there is another answer to decarbonizing our buildings: electrification. Heat pumps can both heat and cool spaces using renewable electricity. Research by RMI has indicated that an all-electric home can be built in California at less cost than homes that use natural gas. This realization has also led to policy action: starting next year, new homes built in California will be required to be all-electric ready and incentivized heavily to be built all-electric, beginning the process of getting homes off the gas grid before gas prices begin to grow.

Even though it might not make sense in buildings, there is a place for green hydrogen in decarbonizing our society. Hydrogen can be used in hard-to-electrify sectors such as high temperature industrial processes, shipping and aviation. A coalition of groups recently launched an initiative called Green Hydrogen Catapult to help bring down the cost of hydrogen with the goal of providing an inexpensive, carbon-neutral fuel to power our future economy. Only time will tell if gas utilities see the writing on the wall and join in this effort to utilize hydrogen where it is needed most.

This is the third in a three-part series about the road to building electrification by experts at RMI. The first part is “What the gas industry doesn’t want you to know about your appliances.” The second part is “No time to waste. Building electrification is a fight for the planet.

Jonny Kocher is a senior associate on RMI’s Carbon-Free Buildings team, where he supports city and state efforts to promote building electrification in the Western U.S.; he lives in Oakland. Zack Subin is a senior associate on RMI’s State Policy Analysis and Climate-Aligned Urbanism teams; he lives in San Francisco. RMI is transforming the global energy system to secure a clean, prosperous, zero-carbon future for all. Follow RMI on Twitter @RockyMtnInst

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