NEW YORK (Reuters) - The boom in shale gas drilling has raised hopes the United States will be able to rely on the cleaner-burning fuel to meet future energy needs, but concerns about its impact on water quality could slow industry’s ability to tap this relatively new resource.
Natural gas is the cleanest burning fossil fuel, emitting about half as much carbon dioxide as coal. For more than a decade it has been the fuel of choice to heat homes and for businesses to generate power.
Many now see gas as a bridge fuel that can drive growth as the economy transitions to cleaner alternatives like wind and solar. But fears that drilling techniques used to fracture the gas-bearing rock could contaminate local drinking water threaten to slow development.
“Environmental concerns do have the potential to slow down shale gas development, but I think the slowdown will be more of a short-term problem,” said Robert Clarke, product manager of Wood Mackenzie’s unconventional gas service in Houston.
“There have been challenges in the past about drilling technology or well stimulation technology and the industry has addressed each one of those successfully,” Clarke said.
Some environmental groups want tighter regulations on air emissions and water disposal and limits on the number of wells that can be drilled in a location, but Clarke said the industry already has taken steps to address some of these concerns.
Horizontal drilling, for example, allows producers to drill multiple wells from one well pad. On-site water recycling has cut the amount of water needed in drilling and the number of trucks needed to cart water away from the drill site.
In addition, he said some rigs and compressors are now powered by electric motors, reducing noise and air pollution.
Earlier this decade U.S. producers were struggling to find new natural gas supplies to keep up with growing demand, as rapid depletion of conventional wells stirred fears of a shortfall in supplies.
While producers were well aware of the vast reservoirs of shale gas in North America, much of that supply was thought to be uneconomical until recent advances in horizontal drilling and rock fracturing techniques made production more viable.
Now shale gas, or gas trapped in sedimentary beds, is seen as having the potential to provide the United States with affordable fuel that will help drive economic growth, reduce dependence on foreign oil and limit emissions for decades.
The United States is estimated to have some 2,000 trillion cubic feet of technically recoverable natural gas reserves, or enough gas at current production rates to supply the country for more than 90 years.
U.S. gas reserve estimates are up more than a third since 2006. Shale accounts for more than 30 percent of the total thanks to upward revisions in some key shale basins like Haynesville in Louisiana or Marcellus in Appalachia.
“From a natural gas perspective, energy independence is definitely a goal that can be attained,” said Gary Adams, vice chairman at accounting and consulting firm Deloitte.
But concerns have been growing about the impact of shale drilling on water quality. Some in the industry fear new laws could raise drilling costs to levels that discourage future development.
“Another layer of federal regulation could make our own resources uneconomical and increase our dependence on foreign countries,” Deloitte’s Adams said.
Hydraulic fracturing, also known as fracking, pumps a mixture of water, chemicals and proppants like sand into the shale formation to split the rock and free the trapped gas.
It takes significant amounts of water to produce gas from shale, but casing and cement are installed when the well is drilled to protect ground water and help recapture any of the fluids that return to the surface as gas is produced.
While the chemicals used may be only a small part of the fracking fluid mix, some are considered toxic or are known causes of cancer, raising concerns about the potential for ground water contamination.
The U.S. Environmental Protection Agency recently found chemical contaminants in some drinking water wells in Wyoming that may have been caused by gas drilling in the area.
Federal laws like the Clean Water Act, the Clean Air Act and the Safe Drinking Water Act are supposed to address many of the environmental concerns about shale drilling. There are also numerous state laws that regulate drilling activities.
But critics say the industry needs tighter scrutiny, claiming there are too many loopholes in some federal laws, while state regulations and enforcement can vary widely.
“We think gas is an important fuel as we transition toward a cleaner energy future. We’re not out to put anybody out of business, but we believe there are cost-effective technologies available that will allow industry to do their work cleaner,” said Amy Mall, senior policy analyst at the Natural Resources Defense Council, an environmental group.
Reporting by Joe Silha; Editing by David Gregorio