General · 9th February 2016
Carbon dioxide is the culprit that usually gets more attention as a greenhouse gas than its lesser-known cohort, methane. But the equally colourless and odourless methane is also a major contributor to global climate change. Indeed, methane, chemically composed of one carbon and four hydrogens atoms (CH4), can have warming effects that are 28 times more warming than CO2 over a 100 year period.
Like carbon dioxide, methane's concentration has also increased in the atmosphere since the Industrial Revolution. Whereas carbon dioxide has risen from 280 parts per million to 400 ppm, about 43%, methane has jumped from 722 ppm to 1,893 ppm, a rise of 162%.
Methane is emitted naturally from the decomposition of organic matter and is an important part of healthy ecological systems. However, it is released in excess during much of our human activity. Agriculture produces huge amounts, principally from plant material, manure and animal flatulence. It is also emitted from garbage dumps — from which it can be easily collected and added to natural gas supplies.
But the biggest source of methane comes from fossil fuels. Some escapes during oil production and large amounts are released when mining coal. Natural gas, however, is about 90% methane, so any release during drilling, fracking, processing or transporting is added to the atmosphere to contribute to global warming. When the effect of this escaped methane is considered, the reputation of natural gas as a “clean energy” quickly collapses — it is, at best, “a transitional fuel” on the way to renewables. When compressed to LNG, it may even be as “dirty” a fuel as coal.
The media is abuzz with examples of methane escaping from natural gas exploration, with fracking being the primary culprit. The fracturing of methane-rich strata to release natural gas is a risky and unpredictable practice. Wells get contaminated, sometimes with enough methane to be ignited at the end of water hoses and taps. Because the gas is invisible and odourless, its escape from induced ground fissures can be difficult to detect and quantify. And sometimes the best of plans can go very wrong.
The latest example is a massive leak in California, an ecological disaster which may rival BP's oil blowout in the Gulf of Mexico. Collected natural gas is sometimes pumped and stored kilometres underground in strata — about 400 such storage sites are located in the US. This particular one, the Aliso Canyon National Gas Storage Facility, operated by the Southern California Gas Company (SoCalGas), was first reported leaking on October 23, 2015, probably from a fractured pipe deep below the surface. By the end of December, it had leaked 72,000 tonnes of methane. It is currently leaking about 30.3 tonnes per hour — 25% of California's annual 20 million tonnes — with little chance that it can be stopped before March, 2016.
Staunching such a leak is extremely difficult and dangerous. This is a gas under huge pressure, extremely flammable and explosive — it could easily be ignited by a spark of static electricity.
Methane is a reminder that we must transition as soon as possible to clean renewable energies. We have another 84 years to reach zero emissions. Can we do it? Not if we can't manage our methane.