Renewable natural gas? That's a thing?

Well, kind of.

Natural gas is 90% methane, a potent greenhouse gas, many times, more potential than carbon dioxide. That's why claims by the oil and gas industry that natural gas should used as a "transition fuel" should be take with a very large pinch of salt.

What, then, are we to make of the concept of "renewable natural gas" (RNG)? Also known as "biomethane" in Europe, RNG means methane produced from biological, as opposed to fossil, sources, e.g. landfills, sewage, food waste, agricultural waste, or forest waste. Because once refined, it is chemically practically identical to regular natural gas, it can be transported, processed, stored, mixed and used in exactly the same way.

The industry claims that it can it can displace natural gas and other fossil fuels. RNG made from plants that captured carbon during their lifetimes is arguably carbon neutral when it is burned. Methane captured from landfills and agricultural and food waste reduces the amount of methane that would otherwise be released into the atmosphere, and when burned it is converted into water and carbon dioxide, a less dangerous greenhouse gas. So, companies like FortisBV and REN Energy International are pushing their RNG products as a solution to Canada's climate change woes.

However, in practice, RNG's carbon intensity depends on how it was produced, and much of it is not as carbon neutral as claimed. Also, biogas and RNG production leaks an estimated 15% of its methane into the atmosphere, a substantial amount of a very potential greenhouse gas. Critics, then, see the whole concept of RNG as just another example of greenwashing. Particularly galling is the promotion of RNG for household stoves, a process that emits a whole host of unpleasant gases including carbon monoxide, formaldehyde and nitrogen dioxide. Methane is methane, they say.

RNG could, though, still make a contribution to decarbonizing some sectors that are difficult to electrify, such as industrial high-temperature heating, heavy duty transport, aviation and maritime shipping, although estimates suggest that it will probably only displace at best 5-10% of current natural gas usage. Also, it is expected to be between 2 and 10 times as expensive as regular natural gas, depending on the comparison being considered.

Is RNG, then, simply a distraction from other better solutions like heat pumps, solar power, etc, as its detractors claim?