Water Impacts

User @Ken Donnelly

Reply to @NatGeoEnergy Where has fracking resulted in contaminated groundwater, or loss of water in wells? Is there evidence of this happening? 7:11 AM - 9 Jul 2015

Other readers such as Ken Donnelly, above, Madeline McGuckin, and Steve Gould wanted to know whether fracking pollutes and/or diminishes water supplies. A U.S. government analysis released in June essentially concluded that in a small percentage of cases, hydraulic fracturing has contaminated or depleted groundwater.

Well operators add chemicals such as methanol and hydrochloric acid to the mix of sand and water injected underground. The concern is that those chemicals, many known to be poisonous and/or carcinogenic, can leach into the water supply, or that gas can escape into the tap water, rendering it flammable.

In Colorado, for example, the Environmental Protection Agency said that faulty well construction allowed methane and cancer-causing benzene to reach the drinking water supply. Still, the EPA found no evidence that fracking activity caused "widespread, systemic impacts" on the country's drinking water.

What about drought-plagued California, asks Kevin K.C. Navarro: Is water use for fracking cutting into the supply there? Water use for fracking has definitely been on the rise in recent years—check out our Energy Snapshot showing the spike—and soaked up 70 million gallons in California last year. But the overall volume of water used for fracking in the United States is less than 1 percent of the total, the EPA notes.

The real issue, according to experts such as National Geographic freshwater fellow Sandra Postel, is that fracking's high water intensity can stress water availability near the drilling site. Given that 9.4 million people lived within a mile of a fracked well between 2010 and 2013, local battles such as those in Denton, Texas, and Longmont, Colorado aren't surprising.

Methane Leaks

User @Scott McLaughlin

Reply to @NatGeo @NatGeoEnergy Is there a major loss of gas to the atmosphere? Is there a net gain in terms of carbon/pollution v. coal? 1:41 AM - 9 Jul 2015

Scott McLaughlin refers to a key issue for the natural gas industry, which often positions itself as a clean alternative to coal. Leaks of methane, the main component of natural gas and a potent heat-trapping greenhouse gas, threaten to undercut the benefits.

The industry has taken measures to contain gas that escapes along various points in the chain from well to end user—see "Oil and Gas Industry Faces Its Methane Problem"—but critics say voluntary measures aren't enough. The Obama administration proposed rules earlier this year aimed at reining in the industry's emissions, though it only targeted new facilities, not existing ones.

Reducing methane emissions from the oil and gas sector is one of five key measures the International Energy Agency recently listed for addressing climate change. Some researchers in California, however, recently found that even without leaks, the shale gas fracking boom won't help reduce carbon emissions by much, in part because it could hinder the growth of solar and wind energy.

The story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.