(Castanet is introducing a new bi-weekly column on sustainablility. Columnist Kristy Dyer has has worked in the sustainability field for 10 years and has written about the subject since 2012. Her column, Sustainability Spotlight will appear on Castanet every second Tuesday.)
Methane is bad. Methane is a powerful greenhouse gas, with a global warming potential approximately 30 times worse than carbon dioxide. It is, in fact, the second largest contributor to global warming. In order to limit climate change to 1.5 C, we need to make immediate and severe reductions in methane emissions.
Natural gas is good. It has the word “natural” in its name. It is a cleaner fossil fuel, creating less air pollution than coal. For every kilowatt hour of electricity, coal emits 1,975 grams of carbon dioxide. Natural gas emits only 700 grams. That’s a 60% reduction.
The paradox of these statements is that natural gas is methane—the methane content of natural gas is 85% to 90%. And natural gas contributes to global warming from the well to your kitchen stove.
Let’s look closer at points where natural gas contributes to global warming, especially flaring at the wellhead and leakage during transportation from well to home.
One of the strangest aspects of drilling for fossil fuels is flaring. Flaring is where natural gas is burned at the site of the well for no productive purpose. The well can be in a developing country, where equipment isn’t available to capture the natural gas. It can be in a remote region where it isn’t cost effective to transport the natural gas. The well might produce small amounts of natural gas that isn’t worth the cost to collect. It may have dangerous variations in pressure that are relieved by flaring. Flaring natural gas at wells generates huge carbon emissions. According to the World Bank, flaring produces 350 million tonnes of CO2e emissions every year.
If flaring is bad, leakage of natural gas is worse. We all know of the danger of natural gas leakage in homes. If you detect the rotten egg smell it is an emergency and you should leave the house immediately and call 911. However, natural gas leakage happens at every step along the way from wellhead to your house.
Even during the flaring process, some gas fails to ignite and is released directly into the atmosphere. The World Bank estimates 40 billion tonnes of greenhouse gases are emitted annually from unburnt methane during flaring. Leakage can happen by design at the well when natural gas is vented rather than flared. It happens due to the extraction process through underground cracks and water pressure changes from the wellhead. There are leaks along the transportation chain and at residences and businesses.
A 2012 study by the Environmental Defense Fund of US systems found 2.3% of natural gas is leaked annually, a total of 13 million tonnes. Natural gas extraction and transportation adds a significant amount to the methane generated by landfills and agriculture.
So, is extracting and using natural gas bad for the planet? The answer comes in two parts. While natural gas is 60% cleaner than coal, solar and wind are 92% and 95% (respectively) better per kilowatt hour than natural gas. These numbers take manufacturing into consideration.
In addition to being cleaner, solar and wind farms are also cheaper to build than natural gas plants. Rather than settle for second best, we should push for state of the art renewables to generate our energy. However, natural gas has a key part to play in the transition to a low-carbon economy.
There are many industrial processes that require high temperatures. One of the most obvious is the production of cement, which requires heating to 2000 C. It is difficult to create these super-high temperatures from electricity. Currently, the high temperatures needed by cement are generated by burning coal and natural gas.
Eventually these industries may be powered using green hydrogen—hydrogen produced by renewable power. Today, we don’t have good alternatives. While we push for better solutions, natural gas may be the best choice for industrial processes.
No one in their right mind would select methane today as a fuel of choice for residential and commercial heating. We need to stop installing new natural gas lines and transition HVAC and hot water heaters to energy efficient electrical appliances.
Natural gas extraction technology needs to be updated to leak less methane, and natural gas transportation should be inspected and monitored for leaks.
We need to invest in research on low-carbon ways to create high temperatures for industrial processes. And finally, when natural gas is touted as a clean fuel, we need to remember it is methane, a potent greenhouse gas that should be handled with care.
Methane is released at each step in both traditional and hydraulic natural gas drilling. Figure by Brad Wierbowski, Used under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International Licence
This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.