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The demand for natural gas is expected to rise by 50 percent over the next 20 years, from 22 trillion cubic feet (Tcf ) in 2004 to more than 33 Tcf by 2024, according to the Energy Information Association. With significant liquefied natural gas (LNG) imports still 10 to 15 years away, unconventional sources of natural gas will continue to drive the natural gas industry. Coalbed methane (CBM) is an unconventional resource whose production has risen from 85 Bcf in 1985 to more than 1,720 Bcf in 2004. CBM now represents 8.3 percent of dry natural gas production and 9.9 percent of proven gas reserves.
 Methane in coal comes from thermogenic and biogenic sources. High temperatures generate thermogenic methane from deeply buried coal, while rain carries microbes and nutrients into coal at or near the surface, where the microbes generate biogenic methane. “For many years, researchers believed that biogenic methane in coals was derived from peat swamps,” says Andrew Scott, president of Altuda Energy Corporation of San Antonio, Texas. “Our research demonstrated that most of the biogenic gases in coal beds are geologically recent, probably formed over the past several hundred thousand years.”
Scott wondered if the natural process could be imitated and sped up. In 2002, he presented the idea of coal bioconversion to Biswarup Mukhopadhyay, an assistant professor with Virginia Bioinformatics Institute at Virginia Tech, who is an expert in microbes that produce methane and live in extreme environments. “A development that will increase CBM production will have a major beneficial impact on U.S. energy security,” says Mukhopadhyay. “One way to achieve this would be to convert a part of the coal to methane.” In collaboration with Altuda Energy Corp., Mukhopadhyay’s team is investigating whether this feat can be accomplished with the activity of microorganisms. “Geologists can often discern thermogenic from biogenic methane, so we are going to sites where geological data has detected secondary biogenic methane,” says Mukhopadhyay. The scientists are examining whether the microbes that live in the coalbed can be encouraged to make methane from coal at an enhanced rate. With endorsement and active support from coalbed methane operators, Scott and Mukhopadhyay’s group have collected samples from coalbed methane wells to look for these microbes. The research has been supported by two grants from the U.S. Department of Energy (DOE). A third DOE grant is funding a search for microbes that will convert paraffin to methane. “Paraffin-associated problems reduce natural-gas production rates and ultimate gas recovery. If paraffin can be digested into methane, it would solve a problem and provide a resource,” says Mukhopadhyay. The entire process of the bioconversion of coal or paraffin to methane will involve several microbes and a series of complex biochemical steps, says Mukhopadhyay. “But the work will generate new science and the parts of these conversion processes might find other applications in the chemical industry.”
As they worked on enhanced methane production from coal, Mukhopadhyay and Scott also became interested in the microbes that consume natural gas. If such microbes can consume methane within confined areas with little air, they might be useful for removing methane in closed coal mines. These methane consumers, called methanotroph, have been collected from methane seeps in coalbeds. This research has also been funded by two DOE grants.
• Virginia Bioinformatics Institute website
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