This year, natural gas became the top rated "environmentally friendly" power source by executives in the energy industry. With natural gas in the spotlight, shale gas is expected to play a more significant role in natural gas-fueled power as well.
Hydraulic fracturing--or fracking--is the high-pressure injection of water, sand, and chemicals into geologic formations to open or enlarge and prop open fractures in the surrounding rock. As gas flows into the well, flowback and produced water are returned to the surface.
Fracking technology isn’t new, but it has significantly increased our ability to extract natural gas from shale and coal bed deposits around the world. The growing use of fracking to bring natural gas to the earth’s surface has raised environmental concerns. Much of the concern swirls around water.
The practice of horizontal drilling and fracking to extract unconventional gas, such as gas found in sandstone or coal beds, has drawn avid supporters and vehement opposition. Poland has embraced it. France has banned it. The United States and other countries are still debating the topic.
Concerns about water use, water and air pollution, groundwater contamination, traffic and public health issues are weighed against the economic and energy benefits of shale gas extraction. Recent dialogue largely focuses on whether we are doing enough to protect the environment and public health, but with little conclusive research completed, the true costs of tapping shale gas supplies are still surfacing.
Shale gas is an abundant energy source and a way to reduce our collective carbon footprint. Fossil fuels today dominate the U.S. energy-consumption portfolio, but the percentage of power generated from natural gas in the United States is expected to nearly double to 40 percent during the next 25 years. The United States and other nations seek to strengthen security by becoming more energy independent. Economics favor regions with growing markets and ample energy supplies. And the risks of hydraulic fracturing are under study. All good.
The potential bad includes use of large amounts of water, for starters. As much as five million gallons of water can be required just to start a well, and each well may have to be fracked a couple more times over its life. That’s especially a problem in water-scarce regions where water demands exceed freshwater supplies. Poorly designed systems can lead to air pollution or allow gas and chemicals to escape into underground aquifers. In addition, wastewater returning to the surface brings varying levels of salt and naturally occurring radioactive materials to the surface with the injected water and chemicals. Although only 0.5 percent of fracking fluid is not sand or water, claims that the remaining chemicals are trade secrets have contributed to concerns about fracking.
Treatment requirements and disposal practices vary by state, but it’s clear that the wastewater from fracking can’t be treated as municipal wastewater. It has historically been injected deep underground or sent to local publicly owned treatment works. But as drilling operations increase, growing levels of salt and naturally occurring radioactive materials in water pose a problem. And hauling wastewater long distances for treatment creates heavy truck traffic and thus more problems, but not problems that can’t be overcome by innovative solutions for water reuse, a topic of growing importance globally.
Effective water management techniques provide solutions to these problems. Water has long been part of oil and gas drilling operations, but drilling companies don’t have to use fresh water for well operations. In Australia, they are required to recycle the water used to extract unconventional gas. In the United States, companies are increasingly looking beyond freshwater supplies, using abandoned mine water, water from stormwater control basins, municipal treatment plant effluent and their own recycled water. Industrial effluent, including power-plant cooling water, offers additional approaches to reduce freshwater withdrawals.
Basic treatment and reuse of flowback water (which comprises approximately one-fifth of injected water) simultaneously alleviates water supply and wastewater disposal problems. Advanced treatment of produced water to remove salt and radioactive materials (which are injected as solids into deep wells) enables recycling of all fracking water. And co-locating more advanced treatment technologies with gas and power infrastructure to handle the longer-term flow of produced water can generate economic and environmental synergies though shared use of rights-of-way and waste heat.
If fracking continues, how can we ensure responsible and effective management of our water resources and otherwise protect our planet and populace in doing so? With effective regulatory oversight, continued research, strict adherence to regulations and industry best practices, better public education, and more widespread reuse of water by well operators, the possibilities run deep.
[Image: Flickr user D.H. Parks]
Dan McCarthy is President and CEO of Black & Veatch's global water business.