What is fossil gas?

Most people haven’t heard of fossil gas – what is it?

You’ve probably heard of natural gas. I try not to use that term, and like many others who are advocating for everyone to do their utmost to address the climate catastrophe, I try to use the term fossil gas intead in any article that deals with using gas as a source of heat.

The two terms refer to the same gas – the combination of methane, ethane, propane, butane and other gases, that are supplied by your local gas utility and that are used to operate furnaces, hot water heaters, stoves, utility-connected barbecues, gas fireplaces, gas fired generation plants, and so on.

The term natural gas is really marketing speak, and creates the wrong impression. It makes people think that this gas is clean, and green, and harmless. (Trucks in my city that run on fossil gas have written on them, in giant print, “Powered by clean, green, natural gas”).

In fact, fossil gas is one of the major contributors to climate change, and we need to do everything possible to stop using it. While masking the gas’s bad reputation in terms of climate impact might not have been the intent of the folks who came up with the term, it’s now heavily exploited by the fossil fuel industry, who would like you believe that burning fossil gas is good for the environment.

Ten or fifteen years ago, fossil gas became popular as a way to wean utilities away from coal as a source of electricity generation. In the short term this was probably a good thing, as fossil gas produces substantially less CO2 emissions per kilowatt hour of electricity generated, than does coal; it also produces lower particulate emissions and therefore produces less air pollution. But in 2023, with the cost of renewable generation well below the cost of any fossil-fuel based generation (coal, gas, or oil) there’s really no reason to build new gas generating capacity, and in many cases it’s actually cheaper to replace a fossil-gas generation plant with solar or wind, because the upfront costs of renewable hardware have come way down in price, and renewable sources are basically free to operate over their lifetime since they need no fuel.

Fossil gas is bad for the environment not just because of the CO2 emissions when you burn it. Methane, the main constituent of fossil gas, is a powerful greenhouse gas. Although it doesn’t last as long in the atmosphere as CO2 (perhaps 10-20 years, as opposed to roughly 1,000 for CO2) it has 40-60 times the warming effect of CO2. The fossil gas you burn converts into CO2, but there is leakage from extraction all the way to combustion:

• Fracking is one of the main ways fossil gas is produced in places like North America. A significant percentage of fossil gas leaks up through small fissures created by the micro-earthquakes that fracking produces.
• Many abandoned oil and gas wells leak fossil gas for years after they are capped.
• A percentage of fossil gas leaks on its way through the distribution system as it passes through storage facilities, pumps etc.
• A percentage of the fossil gas going through your furnace or barbecue may not burn and goes into the air as fossil gas.

Adding these all up you get somewhere in the range of 4-6% of the fossil gas produced leaking into the atmosphere, which at 40x the global warming effect of CO2 means you’re getting 160-240% of the climate impact from the fossil gas that leaks, relative to the climate impact of the CO2 that gets produced when burning the fossil gas.

When I created this website in 2008, I was a big fan of ‘natural gas’ and advocated replacing electric baseboards with fossil gas furnaces, and electric hot water tanks with fossil gas hot water tanks. That probably made sense then – fossil gas was a cleaner alternative than electricity generated from coal, and it is still a better alternative than heating with oil. But several developments have changed the balance:

• High efficiency heat pumps now mean that you can heat your home more efficiently, and more cleanly, with electricity, than with even the most energy efficient furnace or boiler
• Heat pumps are also a very efficient and clean way to heat water. (I have both a whole house heat pump and a heat pump water heater.)
• Electric heat once relied heavily on coal as a source of the electricy used to run it, in many places in North America. While this is still true in some locations, in many states and provinces the load has shifted heavily towards renewables, so the environmental impact of using electricity has gone down relative to using fossil gas.

It may take some getting used to the term fossil gas. But that’s really what it is – gas from fossils. We need to remind ourselves, whenever we speak of it, of the fact that it’s very old, that it has been underground for millions of years, and that that’s where it should stay.

What about Renewable Natural Gas

It’s true that not all of this gas comes from fossil fuels. A small amount of natural gas available through our distribution network is produced through the process of anaerobic digestion of organic matter. When this digestion occurs in places like sewage treatment plants, landfills, and livestock barns, the gas can be captured, and either used to generate electricity on site, or fed into the gas distrubition system and resold as renewable natural gas or RNG. If you’ve made the decision to buy renewable natural gas, I commend you – because at least that’s better than buying fossil gas, and it is “natural” in that it came quite recently from nature (as opposed to coming from nature 200 million years ago).

But RNG is a form of greenwashing too, in that utilities who buy it on your behalf are not creating new RNG capacity, and are not really displacing fossil gas use – that RNG was going to be produced no matter what, and they are just helping the organizations producing that RNG find a market for it. So it doesn’t really solve the problem. If instead you switch from using RNG to using electricity, it frees up that RNG to be used somewhere else that is using fossil gas. The best way forward is for us to stop using fossil gas or RNG for all situations where it isn’t absolutely essential, so we can minimize our greenhouse gas production; save the RNG for the few cases where we absolutely need to burn gas.