Tuesday, June 5, 2012
Fracking, aka hydraulic fracturing, a process for freeing natural gas locked in shale deposits, has caused a boom in natural-gas production in the United States. But some experts worry that the practice results in contaminated drinking water and the release of methane, prompting some localities to limit shale-gas production.
A new analysis by the International Energy Agency says technologies exist—or are in development—that could largely address these concerns. If they're adopted, fracking could be more widely accepted by governments around the world, leading to lower greenhouse-gas emissions and lower energy prices. It they're not, governments could balk, and coal would maintain its dominant place in electricity generation.
The most well-known issue associated with fracking is concern over water use and contamination. Fracking consumes large amounts of water; roughly 20 million liters under high pressure are sent down each well to create the fractures in the rock that free the natural gas. That water use is a huge concern in places such as Texas and some areas of China that have large shale-gas resources and are prone to droughts.
Disposal of that wastewater is another concern. Fracking also has the potential to contaminate drinking water supplies and increase air pollution. And there are concerns that it could actually increase greenhouse-gas emissions due to methane leaks.
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+ Development Solutions, which is part of Southwestern Energy, a natural-gas producer. "You have to go the rest of the way and get regulations in place so that you have a level playing field and everyone is required to do the same thing."
If done right, those regulations could drive innovation by creating a market for new technologies. Ulm recommends caps on emissions that give companies flexibility to choose the best technology. The IEA calls for a combination of such caps, and in some cases specific technology requirements. "With such regulations, you could force innovation to be implemented at a high pace. Technology is what it will take to make shale gas a sustainable resource," Ulm says.