Energy companies using hydraulic fracturing – fracking – to extract natural gas and petroleum from rock and shale formations have inadvertently revealed and, in some cases, created, communities of microbial life thousands of metres below Earth’s surface, according to new research.
Discoveries from the United States could have implications for improved energy production from fracking sites and, more interestingly, point the way forward for scientists investigating the potential for life on Mars.
A study led by scientists at Ohio State University and published in the journal Proceedings of the National Academy of Sciences has uncovered the genetic details of microbes found in wells: a wide array of bacteria thrive in these crevices created by fracking, all producing methane.
That means it is possible that the tiny organisms could create more energy, and from a different source, than the materials the energy companies are pursuing.
The news, however, isn’t necessarily all good. The study’s lead author, Kelly Wrighton, says the microbial lifeforms could prove to be corrosive, toxic or otherwise harmful.
Hydraulic fracturing involves the high-pressure injection of water, chemical additives, sand or some other material into the earth’s subsurface to fracture hydrocarbon-bearing shales and release trapped natural gases.
“This process unintentionally creates a new microbial ecosystem, where a subset of surface-derived microorganisms proliferate in shales more than 2500 metres below the Earth’s surface,” the study says.
The findings will inform the fracking industry, environmentalists and others. But they also have potential implications in the search for extraterrestrial life.
“Finding life in these rocky, salty, hard-to-survive conditions would not be dissimilar to finding life on another planet,” says Wrighton, who recently applied for a NASA grant to aid her inquiries.
“If we want to think about what life would be like if it could exist on Mars, this is probably a pretty good place to start.”
The study notes that in 2016, natural gas became the main source of electricity in the US, the first time that a resource other than coal has provided a bulk of the nation’s power.
It furthers adds that 60% of the natural gas produced in the US comes from hydraulically fractured shales, mostly from Ohio, West Virginia, and Pennsylvania.
The study looked at microbes from several sites in a controlled environment, and presented a rare scientific opportunity, says co-author Michael Wilkins, also from Ohio State.
“These wells are so deep and hard to sample,” he explains. “Access to the liquid in the wells offered us a unique opportunity to understand how these microbes make a living in these briny, high-pressure, high-temperature conditions.”
Previous studies of fracking wells had documented the presence of microbe species and highlighted their ability to make methane, but didn’t offer detailed information about how complex the communities are and how they interact, adds co-author Mikayla Borton.
The researchers took 40 samples from five fracking wells into the lab, conducting genomic analyses and manipulating the environment to draw out microbes that wouldn’t have been identified in a basic field experiment.
They also added a compound called glycine betaine to the samples and tracked gas release over time, confirming that, when prompted, the microbes produced methane.
“It’s really important to know what these organisms can do – to grasp their genomic potential and metabolic interactions – and figure out what impact that might have on the ecosystem,” Borton says.
“We found here that multiple wells have similar microorganisms, which are capable of producing methane. In theory, that could mean that stimulating the microbial community in some way could increase energy yields. That’s not been done in shale yet, but it’s done in other systems, including in coal mining.”
The microbes found in the fracking mines also have parallels with those found in other protein-rich ecosystems, including the human gut and soil, she adds.
“What we learn about these fracking microbes could have the potential to help answer questions about human health – including how plaque forms in our arteries when we have cardiovascular disease,” she says.