What is natural gas?
Your home may be one of more than six million Canadian households that use natural gas to heat their homes, heat water, and cook food. (About 60% of BC homes use natural gas.) If you use gas, it gets to your home via a miniature pipeline, perhaps an inch (25.4mm) in diameter. It gets to that line through a huge network of larger pipelines, the big ones running up to up to 1.22 meters across. There are already 840,000 km of gas and oil pipelines in Canada.
The gas that goes to homes and businesses is processed and purified natural gas — virtually all methane, a burnable hydrocarbon — that starts out as raw natural gas. That raw gas is found in natural geological formations in BC, Alberta, Quebec, Nova Scotia and the Northwest Territories. In BC, at least, those formations are as deep as 3,000 metres underground. Getting the gas to the surface from that deep is tricky, and usually involves ‘hydraulic fracturing’ of the rock formations in which the gas is found. The process is usually called ‘fracking’ for short. More on fracking technology and techniques below.
It’s estimated that BC has around 3,000 trillion cubic feet (a cubic foot is the traditional measure) of natural-gas reserves. Of that, some 2,000 trillion could be extracted using current technology. That’s enough to last a good 150 years. But extraction technology steadily improves, and some say we should really think of 200 years, or even 300. So there’s more than enough supply to meet domestic demand and exports to other countries for centuries.
Where is natural gas found?
This simple graphic to the left shows the main sources of underground natural gas. In British Columbia, we think mostly of gas from shale in northeast BC, from the deep geology of the Western Canada Sedimentary Basin.
Natural gas began forming hundreds of millions of years ago when the remains of marine organisms (small plants and animals) settled on ocean floors or lake beds, forming a sludge that was later buried by layers of sand and silt. Land plants may also have contributed to the organic material.
The pressure and heat created by the enormous weight of many layers of sediment eventually transformed these layers into sedimentary rock. When temperatures got warm enough in the layers, the organic materials were transformed into oil, and with even higher temperatures the oil was transformed into natural gas.
In BC, as we have noted, much of the available natural gas is trapped in sedimentary shale rock up to 3,000 metres underground. To get at that gas, “fracking” is used to open up pores in the rock, to free up the gas. The technique has been in use since 1947, starting in the U.S.
All About Methane
The raw natural gas we extract from underground is 90%-95% burnable methane gas. It may also contain hydrocarbon “condensates” such as ethane, propane, butane, pentane, and also hydrogen sulphide found in “sour gas.” These are removed by processing plants before the gas enters the major distribution pipelines. The condensates and extracted sulphur have their own market value, and can be sold by the operator of the processing plant.
To the processed and cleaned natural gas, your home or business gas company then adds a harmless chemical called mercaptan, to give your gas that distinctive rotten-egg smell. This is for safety, so that if there’s a leak people will quickly know about it. Concern is often expressed about unwanted escapes of natural gas — “fugitive emissions” — from gas wells, processing plants, and operations. And those who are concerned usually point out that methane is a greenhouse gas that contributes to global warming. Methane’s warming effect is said to be 21 or more times more powerful than carbon dioxide, over a long period, but there is less of it and it does not last as long in the atmosphere.
The natural-gas industry tries hard to tackle and limit fugitive emissions, as gas is what they make their money from. Lost gas is lost profit. There also are many natural sources of methane emissions into our atmosphere, among them the world’s farm animals (“cow farts”). Other sources include municipal landfills, sewage, melting permafrost and glaciers, wetlands, rice paddies, and even billions of termites.