Renewable natural gas could help slow climate change, but by how much?

Our planet is changing. So is our journalism. This story is part of Our Changing Planet, a CBC News initiative to show and explain the effects of climate change and what is being done about it.

Renewable natural gas sounds like a great climate-change solution, and it's one that your local gas company may have offered you. But what is it, really?

Here's a closer look at how it's made, the role it could play in slowing climate change, and why some people caution that investing too much in renewable natural gas (RNG) could actually be bad for the climate.

Natural gas is a fossil fuel that's about 90 per cent methane — a chemical compound that's a powerful greenhouse gas, dozens of times more potent than carbon dioxide.

Renewable natural gas is biomethane — methane that comes from biological sources, which could include landfills, sewage and food, agricultural or forestry waste.

Because natural gas and renewable natural gas are practically chemically identical, they can be mixed, processed, stored, transported and used the same way. 

According to Environment Canada, under Canada's Clean Fuels Regulation, RNG must:

In two main ways:

By displacing natural gas and other fossil fuels. Because renewable natural gas ultimately comes from plants that captured carbon during their lifetime, it's theoretically carbon neutral when it's burned. That allows it to decarbonize gas-fuelled trucks and industrial processes using existing infrastructure.

Doug Slater, VP of external and indigenous relations at the gas company FortisBC, says that can even apply to furnaces in buildings.

"The great thing about renewable gas is that our customers don't need to make any changes to their homes and businesses in order to use it," he said.

By capturing methane from organic waste (such as landfills, manure and food waste) that would otherwise get released into the atmosphere and contribute to climate change. When it's burned instead of being released directly, methane is converted into water and carbon dioxide, a greenhouse gas with a much lower global warming impact than methane itself.

Because of that, RNG has the potential to be not just carbon neutral, but carbon negative due to those "avoided emissions." 

Vincent Morales, manager of legislative and regulatory affairs for the Coalition for Renewable Natural Gas, noted that methane from waste can represent more than five per cent of a country's greenhouse gas emissions: