Potential and room for improvement: Stanford University’s Dr. Mark Zoback on hydraulic fracturing (fracking) techniques for natural gas extraction


Making hydraulic fracturing workable, for people and the environment: thoughts from Stanford’s Dr. Mark Zoback

by Cristina Deptula 

The term ‘fracking’, or the process of extracting natural gas from shale rock deposits more properly known as hydraulic fracturing, frequently gets slapped across news headlines and blogs. Before getting too excited one way or another, it makes sense to first understand the procedure.

Dr. Mark Zoback, a geophysicist at Stanford’s Precourt Institute for Energy, outlined how fracking works during his lecture for the Northern California Science Writers’ Association last month at San Francisco’s Thirsty Bear tapas restaurant.

Fracking involves pumping large amounts, up to 4 million gallons, of high-pressure water mixed with small amounts of sand and chemicals, underneath clay-rich sedimentary rock deposits. Gas bubbles up through the induced fractures, and then gets collected for energy production. An L-shaped well allows for the harvesting of natural gas from many small pockets within the rocks, rather than only tapping into what’s directly under the well.

Scientists in the United States and in China are interested in further developing natural gas as an alternative to coal power for economic and environmental reasons. Natural gas is cheaper to convert into energy and releases less carbon dioxide and fewer atmospheric pollutants than coal when burned.

“We have to get our energy from somewhere,” Zoback reminded the audience, “and saying no to fracking for gas is really saying yes to more coal.” However, he urged the scientists and journalists in attendance to use the time the natural gas power buys us to develop even more efficient and nonpolluting energy sources.

The USA possesses large reserves of natural gas. Within the United States, Zoback asserted, our shale deposits could contain enough to power all of our gas-burning devices for a hundred years. A recent Popular Mechanics article suggests the Marcellus shale, a large deposit between West Virginia and Pennsylvania, alone could cover our national gas requirements for 20 years.

However, fracking can pose safety and ecological risks. According to Zoback and other scientists, current concerns with fracking include possible surface contamination from spills, air pollution from the extraction process, methane leaks from fracking wells, the volume of fresh water required for the process, and the possibility of polluting groundwater and triggering earthquakes by destabilizing rocks.

A fairly recent report from several scientists, including the Environmental Defense Fund’s Fred Krupp, came to the conclusion that shale gas deposits could be extracted and used in an environmentally responsible manner. Still, the team prescribed 20 recommendations concerning how to make the process safer and cleaner.

Zoback does not oppose all fracking, only those projects which in his view pose a danger to the environment, workers or local residents. Yet, he often advocates for more environmental precaution and mitigation than the leading oil and gas industry advocacy group, the American Petroleum Institute (API) supports.

For example, he would like to see more attention paid to methane leakage from fracking sites than industry leaders recommend, as methane gas contributes more to the greenhouse effect, trapping heat within Earth’s atmosphere, than carbon dioxide. Zoback did say methane leakage could effectively be prevented through improved construction techniques, which should be implemented.

Zoback also supports full disclosure of the chemicals used in fracking fluid, although he emphasized how the chemicals comprised only half of one percent of the water solution. “These are common substances we use in our pools, detergents, glass cleaners,” he said, holding up a chart to illustrate consumer products containing the same chemicals used in fracking.

He made a valid point about the reduced dangers from a substance as its concentration becomes more diluted, and keeping things in perspective. After all, we do not need to live our lives in bubbles to avoid exposure to even one molecule of a potentially toxic chemical. More detail on the safety tests that had been done, and on how and why scientists felt these chemicals at these concentrations in our water supplies did not pose any danger to humans or ecosystems could have helped assure the audience here, though.

To minimize the amount of freshwater required, Zoback encouraged greater re-use of fluid from one drilling project to another. This could be made more feasible through pad drilling, he said, with many fracking wells located in one place. And known environmental restoration techniques can be employed to allow the area to return to its natural state after engineers finish the gas extraction.

As for earthquakes, Zoback pointed out that we’d seen only four small, non-destructive earthquakes triggered by our nation’s 150,000 fracking wells. We can also mitigate earthquake risk by avoiding injecting fracking fluid into known seismic faults, and by limiting the rate of injection.

Hydraulic fracturing technology, to Zoback and his Stanford colleagues, comes with its share of dangers and technical and environmental challenges. Yet, the procedure also could make available an accessible supply of energy that could prove more efficient and sustainable than its leading alternative, coal. Hence, he and others advocate intelligent, cautious, and responsible development of shale gas deposits, coupled with pro-active planning, monitoring, and the willingness to halt work at fracking sites where it would bring about safety or environmental problems.

“Fracking can form a blue bridge to a green future,” he said, “but non-carbon-based energy sources need to be on the other side of that bridge.”


Author’s note: Dr. Richard Muller, faculty senior scientist at Lawrence Berkeley National Laboratory, also presents a nuanced picture of fracking technologies in his book Energy for Future Presidents: The Science Behind the Headlines. If this article interests you, I would recommend his book.


Cristina Deptula is a writer from San Leandro, CA who helps edit Synchronized Chaos Magazine and may be reached at cedeptula@sbcglobal.net.


Article in Grist magazine about fracking technologies and their various impacts: http://grist.org/basics/fracking-faq-the-science-and-technology-behind-the-natural-gas-boom/


Popular Mechanics piece on the top ten misconceptions about fracking: http://www.popularmechanics.com/science/energy/coal-oil-gas/top-10-myths-about-natural-gas-drilling-6386593