(Bloomberg News) Replacing coal with natural gas cuts the creation of greenhouse gases that cause global warming, a Cornell University researcher has concluded, rebutting the findings of colleagues at the university.
Lawrence M. Cathles, a professor in the department of earth and atmospheric sciences, released a paper that says even if high rates of natural gas are leaking out after hydraulic fracturing and during transport, gas will still provide a net benefit over time.
"The only thing that really counts is the amount of carbon dioxide you put in the atmosphere," Cathles said in an interview today. Because gas releases less carbon dioxide than coal or oil when combusted, "the story is quite clear that we would be very well advised to substitute natural gas."
The impact of natural gas on climate change has attracted attention as the spurt in production from hydraulic fracturing, or fracking, has pushed down prices and prompted power producers to shift from coal to gas. Utilities generated as much power from natural gas as coal in April, the first time natural gas equaled coal generation since the government started keeping those records, in 1973, the Energy Information Agency said July 6.
Cathles' Cornell colleagues Robert Howarth and Anthony Ingraffea published an article last year that said leaks of methane from fracking, in which water, chemicals and sand are pumped into the ground to break apart rock and free gas, mean the use of natural gas could actually cause more global warming than coal.
The differences between the researchers hinge on two points: First, estimates of venting and leakages during gas production, and second, the time frame evaluated. Methane is a more potent greenhouse gas than carbon dioxide, but it's removed from the atmosphere in less than 20 years, while carbon dioxide can persist for centuries.
Electricity production is the primary source of greenhouse- gas emissions in the U.S., according to the Environmental Protection Agency.
Howarth and Ingraffea used data from the EPA to develop its estimate of a leakage rate of up to 7.9 percent for methane, the key component of natural gas. Cathles says that estimate is off, basing his analysis on subsequent industry data and the fact that the release of that much natural gas would be both unhealthy and could pose a danger of explosion. Also, companies wouldn't allow that much gas to escape freely, he said.