Wyoming Research Focuses on Nutrient Injection to Coal Seams
Microbes are continually converting the subsurface hydrocarbon deposits to natural gas, and if managed properly, are touted as being able to increase the recovery of coal-bed methane. Luca Technologies Inc., based in Denver, Colorado, said laboratory evidence indicates that anaerobic microbes, bacteria that live in the absence of oxygen, are turning the coals of northeast Wyoming into methane.
The company has coined the term "geobioreactors" to describe the microbial conversion of coals, organic shales, or oil to methane gas, and believes careful management may offer a long-term solution to U.S. energy needs.
"Our research on native coal, water and microbial samples from the Powder River Basin (PRB) has determined that PRB coals can produce natural gas in real time," said Robert Pfeiffer, Luca's president and chief executive officer.
"This finding suggests that the (methane) gas in the PRB need not be an ancient remnant of microbial activity, as generally believed, but instead is being actively created today."
Luca scientists say that methane production can be increased or decreased by altering the microbes' access to water or nutrients, or that production can be halted entirely by exposing the organisms to oxygen or heat sterilization.
"This finding holds the potential of turning what is today thought to be a finite energy resource into a renewable source of natural gas that could potentially go on for hundreds of years," Pfeiffer said.
Maximizing recovery of methane from microbial conversion will require amending current operating practices as well as reviewing the legal and regulatory framework of energy development, he said.
Luca Technologies has raised $76 million to scale up a process that uses coal-digesting microorganisms to convert coal into methane. The process is designed to operate underground, inside coal beds. Methane, the key component of natural gas, can then be pumped out and used in the same applications as conventionally produced natural gas.
As little as one-hundredth of 1 percent of the coal in the United States converted into methane by microbes would supply the country's current annual natural-gas demands, says Andrew Scott, a former professor of economic geology at the University of Texas at Austin. Scott is the founder of Altuda Energy Corporation, based in San Antonio, TX, which is developing a similar process.
Most natural gas is the product of heat and pressure over millions of years. But Scott, working at the University of Texas in the mid-1990s, helped show that a significant fraction of natural gas is constantly being produced by microorganisms that feed on coal. First, one type of microbe breaks the long hydrocarbon molecules found in coal into shorter molecules. Other microbes convert these molecules into organic acids and alcohols. Finally, microbes called methanogens feed on these and produce methane as a byproduct of their metabolism.
The researchers at Luca have learned to increase the amount of methane that these microorganisms produce, both in laboratory experiments and inside coal beds, by adding various nutrients and otherwise changing the chemistry of the microbes' living environment.
The other company looking to tap into the new source of energy, Ciris Energy, got a $4.8 million matching state grant in 2009 to build an above-ground pilot facility that would employ microbes to turn coal into methane.
Luca and Ciris Energy have begun experimenting with using this type of microbe-friendly formula in gas wells that were drilled into coal deposits years ago. The companies have been spiking the wells with substances including calcium, magnesium, phosphate and glycerol, which encourage the micro-organisms to reproduce, feed and release the coveted methane gas. The hope is to get old and nearly tapped-out coal-bed methane wells to double or perhaps triple gas production.
Mark Finkelstein, Luca's vice president of bioscience, says that the company has tested its methods in coal beds where wells had been drilled to collect natural gas (about 10 percent of the natural gas mined in the United States comes from coal beds). Many of these wells had stopped producing natural gas, or produced too little to be profitable. After treatment, production increased, and the wells became profitable again, Finkelstein says.
Luca officials cast aside environmental concerns, saying its process for tapping into natural gas is more eco-friendly and efficient than drilling because the wells, roads and pipelines already are in place. Acquiring methane from existing coal beds requires very little new infrastructure, Luca says, and puts to use byproduct groundwater by pumping the water back down into the coal-bed methane wells.
About 30,000 coal-bed methane wells have been drilled in the Powder River Basin in northeastern Wyoming over the past 15 years. About half are nearly or completely tapped out. Many other coal-bed methane wells have been drilled elsewhere in the nation, with thousands more likely to be drilled in the coming decades.
Finkelstein says that based on initial results, the company's process could extend the lifetime of natural-gas wells. Conventional techniques for extracting natural gas from coal kill the gas-producing organisms found naturally in these coal beds, first, by removing the water that they need, and second, by exposing them to oxygen, which is deadly to them. By carefully maintaining conditions favorable to the microorganisms, the company allows them to continue digesting the coal and producing methane. The company could also employ its techniques to collect useful fuel from coal that's inaccessible to conventional mining, Finkelstein says.
Scott says that it's still unclear how much of the coal reserves in the United States can be converted into methane. Much depends on the nature of the coal bed, including factors such as the surface area of the coal that the microbes feed on.
Louisiana Research Focuses on CO2 Injection to Coal Seams
Something amazing is happening in the Wilcox formation, a coal-bearing stretch of bedrock beneath central Louisiana. Bacteria that naturally feast on carbon dioxide (CO2) and coal in the presence of water are working overtime, producing methane (CH4) as a byproduct.
Why is this so special? The CO2 isn't naturally occurring. In the 1980's an oil company working in the area injected it into a deep underground well in an effort to push out more petroleum. The well was later abandoned. But since then microbes have been busy taking our waste CO2, some hydrogen atoms out of the coal beds, and a few other nutrients and turning it into a fuel we can burn for energy.
This finding comes via a paper by Jennifer McIntosh of the University of Arizona and a team of researchers that's just been published in GSA Bulletin.
It raises an exciting possibility -- instead of destructively mining coal, burning it, and emitting CO2 as a greenhouse gas, what if we left it in the ground and seeded it with bacteria and CO2? The team's results show what no one in the scientific community has before -- that microbes may convert CO2 to natural gas on fast enough timescales to be a useful source of energy.
For further details onthe research and pilot projects to bioconvert coal to methane, see the following:
This article was excerpted from publically available information, and was authored by Rick Wilson, Acacia Environmental Group LLC. Any opinions expressed in this article are those solely of the author, and are not intended as legal or professional guidance to any specific readers. For more information on the author see here.