But the IEA report concludes that fracking, like many other practices in industries that involve hazardous chemicals, can be made relatively safe with regulation. The IEA estimates that the measures needed to make fracking safer would add about 7 percent to the cost of an average well.
Significant levels of methane, the main component of natural gas, have been found in drinking-water supplies near some fracking sites. Some environmentalists have suggested that the fracking process, which creates fractures in shale, could create a path for natural gas and other chemicals to reach aquifers and mix with drinking water.
But according to the IEA report, that doesn't seem to be the problem in most cases. Fracking usually takes place hundreds of meters below aquifers, and it's easy to stop the propagation of fractures. Cracking the rock requires high pressures. Stop applying the pressure, and the rock fracturing stops. However, some fracking sites are relatively near to the level of drinking water, and the IEA suggests it might make sense to ban the procedure at such locations.
The IEA says the contaminated water is most likely the result of producers building substandard natural-gas wells, which are lined with metal casings and cement to keep the natural gas from contaminating aquifers. But in some cases, producers have done a poor job of cementing, allowing channels for natural gas to form. "Whenever there was a gas leakage, it came out because the cement was not well done," says Franz-Josef Ulm, a civil and environmental engineering professor at MIT. That problem could be solved by cementing properly and then carefully monitoring the well's integrity. "When it comes to cementing, the solutions are out there. The question is whether they are being applied," Ulm says.
New technology could greatly reduce the amount of pressure needed for fracking, making it far easier to build safe wells, Ulm says. Researchers are learning that shale is particularly fracture-resistant because of the presence of a small amount of organic material that binds together inorganic particles. Targeting these materials by applying a special solvent could weaken the shale and make it far easier to free the natural gas.
There are also opportunities to reduce water use by using fluids other than water—such as propane (which brings its own environmental challenges)—or mixing carbon dioxide or nitrogen with water to create foams. Eventually it may be possible to mix small amounts of water with solid particles designed to easily flow, Ulm says.
Another contamination fear involves the chemicals that fracking companies add to the water. The biggest concern isn't the chemicals once they're mixed with the water, since they're so dilute, but rather the handling of the chemicals in concentrated form. Spills on the surface could soak into the ground and contaminate drinking water. The solution is to line the area where chemicals are handled with plastic and monitor any leaks. Researchers are also developing less-toxic chemicals, or techniques to eliminate the need for them.
Yet even if these chemicals can be dealt with, wastewater remains a challenge. The water that flows back to the surface is contaminated not only with the chemicals originally mixed in at the surface, but also with chemicals, heavy metals, and, in some cases, naturally occurring radioactive materials from deep underground.
As the water returns to the surface, natural gas and other hydrocarbons that were released by the fracking come with it. In many cases, that gas is allowed to escape into the atmosphere until the water stops flowing. The main component of natural gas—methane—is a greenhouse gas many times more powerful than carbon dioxide, so this practice could offset any greenhouse-gas emissions reductions that would come from burning natural gas rather than coal. However, simple technology exists to capture the natural gas at this stage.
Implementing these technologies will likely require regulation. "It can't just be counting on companies to adopt best practices, because you'll only have a certain percentage of the well operators doing it," says Mark Boling, president of V
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