For several decades, we have been told that natural gas is the bridge fuel in the transition from coal to renewable energy. During this period, carbon emissions from American power plants shrank by 40 percent. Hundreds of coal-fired plants have been retired, many being replaced by natural gas plants.
For years, methane leakage — from extraction wells, processing plants, and pipelines that transport the gas — has been a concern. Why? Because methane is 80-90 times more potent as a heat-trapping gas than carbon dioxide, at least in the short term, and natural gas is almost entirely made up of methane. Since most of the data on leakage has come from the gas industry, the figures published led us to believe that little gas escaped, that the problem was insignificant. However, as independent researchers, using increasingly sophisticated equipment, often carried in aircraft, drones, or satellites, have measured leaks at well-heads, plants, and trunk pipelines, the quantities being recorded are much larger. A recent study found that it takes only 0.2 percent of gas to leak from the production and supply system to be as big a driver of climate change as coal. The numbers being recorded by independent scientists consistently show results that are multiples of this equivalency figure.
As awareness of natural gas’s contribution to climate change has grown, many communities, especially in California, have started banning it in new construction. As a result, the industry is shifting to exporting it in the form of liquid natural gas (LNG). Supercooling the gas to minus 257 degrees Fahrenheit, the temperature at which it condenses into a liquid, reduces its volume 600-fold, making it easier to export. Specialized ships with insulated storage tanks are used for shipping. The storage tanks inevitably absorb some heat, causing some LNG to re-gasify. The “boil-off” gas must be released to maintain the tank pressure. Robert Howarth, a methane expert at Cornell University, says that at best, over its life cycle, LNG is a bigger contributor to greenhouse emission than the burning of coal, 2-3 times greater per unit of energy.