By Jonny Lupsha, Wondrium Staff Writer
Natural gas used in the home is made from methane. It comes both from within petroleum deposits and without, and is refined at a processing plant. However, gas stoves are worse for climate change than previously thought.
Climatologists had already established that fossil fuels, including natural gas, were contributing to climate change. A new study shows that gas stoves are actually far worse offenders than previously believed. Even when gas stoves are turned off, they release 2.6 million tons of methane into the air every year. It’s said to be the same amount of greenhouse emissions as 500,000 cars.
Alongside coal and oil, natural gas is a popular fossil fuel. In his video series Everyday Engineering: Understanding the Marvels of Everyday Life, Dr. Stephen Ressler, Professor Emeritus from the United States Military Academy at West Point, explains how it’s produced.
Associated and Non-Associated Gases
Methane, the natural gas we use to cook and heat our homes, is the lightest of the alkane hydrocarbons. However, depending on where it’s found, it can be separated into two categories.
“In the U.S., about 1/4 of natural gas production is associated gas—meaning that it’s found within, and extracted from, petroleum deposits,” Dr. Ressler said. “In these deposits, methane is dissolved in the oil and kept in solution by the very high pressure underground; but as the mixture is brought to atmospheric pressure at the surface, the methane comes out of solution naturally.”
According to Dr. Ressler, until gas pipelines were developed in the 1950s, associated gas was considered an unwanted byproduct and burned off in the field. Today, it’s captured and piped to a gas plant, where it’s processed and sold. Of course, associated gas is in the minority of the natural gas we use.
“The remainder of U.S. natural gas production is non-associated gas—that is, it’s found in gas fields and in coal beds separate from oil deposits, but extracted using essentially the same drilling process [as oil],” he said. “As it comes from underground, natural gas is mostly methane. Nonetheless, it still requires refinement at a natural gas processing plant to remove water vapor and impurities, and to separate and capture small amounts of other gaseous hydrocarbons—ethane, propane, butane, and pentane.”
Exploiting Shale
Since the turn of the millennium, large-scale exploitation of shale gas—especially in North America—has led to drastic change in natural gas production. Traditionally, shale is literally difficult to crack, and most large shale reserves have been left untouched. However, two technological developments have enabled the spike in extracting gas from shale.
“The first is horizontal drilling, which is used to maximize the surface area of the borehole within a shale stratum,” Dr. Ressler said. “This process requires a remotely controlled downhole drilling motor to control the direction of the borehole deep underground.”
The second technology is hydraulic fracturing, or “fracking,” in which a mixture of water and chemicals are shot at high pressure down into the borehole to create fractures in the shale, through which gas can escape. According to Dr. Ressler, it’s revolutionized the economics of energy in countries where it’s used. It reduces dependence on foreign fossil fuels and lowers prices.
However, fracking comes with a big cost to the environment.
“Although fracturing fluid is 99.5% water, hundreds of thousands of gallons of it are used on a typical site,” Dr. Ressler said. “More than half of this fluid is eventually recovered, but the rest remains underground. Thus, at a given site, thousands of gallons of chemical additives—friction reducers, rust inhibitors, and such—are left below the surface with the potential to contaminate aquifers.”
Not only have cases like these been documented, but so have methane emissions and even evidence that fracking causes earthquakes.
The full consequences of fracking are yet to be understood.