Renewable natural gas? Isn’t that an oxymoron? How can a fuel that we burn be a renewable source of energy?
Although you may know what natural gas is, if you’ve never heard of Renewable Natural Gas (RNG), these are valid questions. In this article, we’re going to explain:
- What RNG is and where it comes from
- How RNG reduces harmful emissions
- 2 examples of Canadian RNG projects happening now
A bit of background
Before we go too far, let’s discuss regular natural gas. If you want a deeper explanation, we published another article all about this topic.
What is the basic composition of natural gas?
Natural gas is mainly made of methane molecules—the simplest hydrocarbon in existence.
Where does natural gas usually come from?
Natural gas is extracted from underground rock and shale formations in the earth.
How is natural gas harvested, stored, and distributed?
We drill wells into gas-rich formations underground. The unprocessed gas flows into nearby gas plants. There, we remove water and other impurities like sulphur dioxide.
After processing, the gas gets transported through a network of pipelines. It can go into underground storage facilities or right to end consumers.
How is natural gas used?
Besides the obvious uses (heating homes, cooking), natural gas has many applications.
One of natural gas’ main uses is in electricity generation. Natural gas has a high heat value compared to other fuels. This, plus its affordability and reliability make it a preferred electricity production method.
In this way, natural gas keeps electricity costs down and makes it more reliable.
Natural gas can also be a feedstock for other products like hydrogen or fertilizers.
What is RNG?
Now you know that natural gas is mostly made of methane gas.
On a molecular level, renewable natural gas is indistinguishable from conventional natural gas. But instead of being recovered from underground, it’s produced from organic waste.
There are many naturally occurring processes that release methane into the atmosphere. This means that we can harvest RNG from a variety of sources including, but not limited to:
- Decomposing organic waste
- Off-gassing of landfill
- Raising livestock
- Wastewater treatment
What makes it renewable?
Methane is a by-product of many natural processes, with or without human involvement. Part of what makes it renewable is just that. We’re harnessing energy from the life cycle of living things.
Also, burning RNG releases biogenic carbon dioxide into the atmosphere. In other words, these emissions are part of the earth’s natural carbon cycle. This means that RNG combustion is a carbon neutral process.
How is RNG captured and purified?
The process of RNG production often involves the capture of methane emissions preventing them from going into the atmosphere. These emissions are then purified and reintroduced into the natural gas system.
Source: Canada Energy Regulator. Market Snapshot: Two Decades of Growth in Renewable Natural Gas in Canada.
One of the most common technologies for producing RNG is anaerobic digestion. In this method, organic wastes and by-products are placed in an anaerobic digester. Inside the anaerobic digester, bacteria break down the organic waste to produce methane.
Like traditional natural gas, the biogas needs to be purified once it leaves the digester. This removes impurities like water and sulphur dioxide.
It can then be integrated into our natural gas infrastructure with traditionally produced natural gas.
The benefits of RNG
It’s good for the planet
When methane gas isn’t stored and distributed safely, it’s a wasted resource. If we don’t capture and use this energy, it’s emitted into the atmosphere.
Capturing RNG means significant emission reductions. Methane loose in our atmosphere is about 25 times more harmful than carbon dioxide.
By using RNG, one molecule of methane transforms into one molecule of biogenic CO₂;. This brings the carbon balance from a factor of 25 to zero. This is why some experts consider RNG to be carbon negative.
Putting our waste to work
Let’s do a little thought experiment.
Agriculture and waste are significant contributors to Canada’s greenhouse gases (GHGs). According to the National Inventory Report, methane emissions in these two categories were equal to nearly 50 MT of CO₂e in 2021—capturing this methane would decrease Canada’s total emissions by that amount.
But this is only one part of the emission reduction. Using it as RNG offsets gas use elsewhere, resulting in another 6 MT CO₂e reduction in GHGs.
RNG integration in Canada
Natural gas producers have begun injecting RNG into the existing natural gas networks. Many utilities are also offering voluntary RNG programs to their customers.
If you live in British Columbia, Quebec, or Ontario, you can opt in to support RNG projects. By paying a little more for your gas, you’ll be increasing the amount of RNG in your supply over time.
Current RNG projects
Coop Agri-Énergie in the Warwick region of Quebec
Source: Coop Agri-Énergie Warwick
Coop Agri-Énergie Warwick has been in operation since 2021. They produce and inject RNG into Energir’s natural gas system.
Their plant produces RNG using agricultural waste such as manure and crop residues. The facility produces about 2.3 million m³ per year. That’s equivalent to taking 1,600 cars off the road.
Ontario’s largest RNG facility in Niagara Falls
Ontario’s largest RNG production facility is currently under construction in Niagara Falls. This plant will produce RNG by capturing landfill gas. The plan is to inject it into Enbridge’s natural gas network.
When completed, the plant will produce enough gas to heat 8,750 homes and reduce GHGs by 48,000 tonnes per year.
Renewable natural gas is great for Canada
RNG prevents environmental damage and is making our natural gas ecosystem even more efficient and reliable. Renewable natural gas is a win-win.
Even if we can get rid of carbon emitting energy sources, our society will continue to generate waste. Harnessing the power of that waste is the type of thinking we need to reach our sustainability goals. As we get better at integrating RNG into our system, things will only get better.
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