In November of 2016, the amount of American electricity generated by coal fell below 30 percent for the first time in 45 years. That continued a downward trend in America’s consumption of coal that began in 2007. In April of 2015, more of America’s electricity came from natural gas than coal. In April of 2010, 44 percent of America’s electricity came from coal. Only 22 percent was generated by natural gas.
The industry claims natural gas releases 45 percent less carbon dioxide into the air than does coal. Scientists peg the amount of CO2 released by natural gas at roughly half the amount released by coal.
Natural gas is mostly composed of methane. Unburned methane is a 70 percent more potent greenhouse gas than is carbon dioxide. Whenever there is a leak in the production or distribution of natural gas, methane escapes into the atmosphere. One study found that if 3 percent of methane produced leaks, into the atmosphere, there is no difference to the climate between coal and gas.
The burning of natural gas produces less air pollution than does the burning of coal.
Hydraulic fracturing, fracking, is a technique designed to get gas or oil from shale rock. A high-pressure mixture of chemicals, sand, and water is used to fracture rock. The fractures in the rock release the gas. Several studies have shown that air and water pollution related to fracking is creating health problems ranging from skin irritation to upper-respiratory problems.