By Taylor Kuykendall
Switching from coal to natural gas, which is thought by many to be the cleaner, greener alternative, may not pack all the environmental benefits once thought.
While emissions measured at the smokestacks of traditional coal-fired power plants versus new natural gas plants put natural gas as the clear winner in the low emissions race, a look at the entire process may prove the earth-friendliness of natural gas has been overstated. A study by ecology professor Robert W. Howarth, of Cornell University, found that over the “life-cycle” of production, natural gas may have some pretty serious consequences for the environment.
“Natural gas is being widely advertised and promoted as a clean- burning fuel that produces less greenhouse gas emissions than coal when burned,” Howarth writes. “While it is true that less carbon dioxide is emitted from burning natural gas than from burning coal per unit of energy generated, the combustion emissions are only part of (the) story, and the comparison is quite misleading. A complete consideration of all emissions from using natural gas seems likely to make natural gas far less attractive than other fossil fuels in terms of the consequences for global warming.”
Howarth looked at high-volume, slick water hydraulic fracturing (HVSWHF), also known as hydrofracking, or fracking, processes and found that methane leakage during the entire production cycle may expose the environment to higher levels of greenhouse gases than even the mountaintop removal extraction of coal. Howarth warns these are purely estimates but further suggests greenhouse gas emissions from fracking-obtained natural gas “are estimated to be 60 percent more than for diesel fuel and gasoline.”
Much of the estimation stems from 2006 data released by the EPA that estimated a methane leakage rate of about 1.5 percent of natural gas consumed. Leakage of methane is of particular concern because it is a much more potent greenhouse gas than carbon dioxide.
“The leakage of methane gas during production, transport, processing and use of natural gas is probably a far more important consideration,” Howarth wrote. “Methane is by the far the major component of natural gas, and it is a powerful greenhouse gas: 72-times more powerful than (carbon dioxide) per molecule in the atmosphere.”
Howarth has even suggested a moratorium on obtaining natural gas from shale, an energy-intensive process that further contributes to greenhouse gas emissions.
Instead, Howarth suggests, the nation should be focusing its attention on renewable sources of energy.
“Far better would be to rapidly move towards an economy based on renewable fuels,” Howarth wrote. “Recent studies indicate the U.S. and the world could rely 100 percent on such green energy sources within 20 years if we dedicate ourselves to that course.”
Howarth’s study, published early in 2010, is loaded with uncertainty, a fact he readily admits. Industry officials were quick to dismiss the preliminary study.
Dan Whitten, a spokesman for America's Natural Gas Alliance, told Reuters news service that Howarth’s study is dismissible.
“We concur with the author’s own assessment that this two-page draft is ‘highly uncertain,’ that the ‘numbers should be treated with caution’ and that there is ‘no rigorous estimate’ to support its conclusions,” Whitten said.
Tom S. Jones, a Marshall University professor who studies the impact of mountaintop removal practices, said natural gas may be more damaging to the environment than mountaintop removal.
“The Marcellus could potentially have more impact, over a broader area, because the areas we can mountaintop (mine) are somewhat isolated in West Virginia — the southern coalfield, the northern coalfield,” Jones said. “The Marcellus affects a much broader area because it generates this super-saline saltwater, and there’s no way, no cheap way to fix that.”
Possible financial gain makes it hard for some to sit back and consider the possible environmental impacts, he said.
“The money is on everybody’s side — the state’s side, the landowners’ side, the gas company’s side. It doesn’t help the situation. It doesn’t help the clarity.”
Beth Little, of the West Virginia Highlands Conservancy, said the damage from a natural gas site compared to a mountaintop removal site is “near equal.”
“If they do as many wells with these five-acres pads all over, they are like mini-mountaintop removal sites. It is about as bad but more pervasive. It’s not as clean as they are touting.”
ProPublica, a public interest journalism organization, reported early this year that the EPA had doubled its estimates of methane leakage from pipes and gas wells.
According to ProPublica, “Methane levels from the hydraulic fracturing of shale gas were 9,000 times higher than previously reported. When all these emissions are counted, gas may be as little as 25 percent cleaner than coal, or perhaps even less.”
Researchers continue to work to determine the relative “cleanliness” of various energy sources as lawmakers try to make decisions on the regulation of each industry.
Though coal is often looked at as the baseline for dirty energy, it too has been attempting to clean up its act.
While the definition of “clean coal” covers various technologies, at the forefront are carbon sequestration and carbon capture technologies. The techniques, currently being explored by academia as well as the coal industry, attempt to reduce the total “carbon footprint” of coal by reducing emissions or capturing and storing emissions away from the atmosphere.
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