In testing completed at NETL, researchers found the microbes from the CBM well, which was drilled in an Appalachian coal seam as part of a mining operation, generated a biocatalyst that outperformed other biocatalysts from microbes collected at oil and natural gas well sites and other locations.
“Microorganisms have a diverse metabolism and can drive many chemical reactions,” said NETL’s Djuna Gulliver, an environmental engineer. “However, when they are grown and enriched in our laboratory, they can serve as highly capable tools that convert CO2 to acetate, an inexpensive chemical that has a wide range of uses.”
The recently developed biocatalyst converts the CO2 feedstock into what Gulliver calls “bio-acetate,” which can then be used to produce food additives, a pickling agent, a laboratory reagent and other useful products. It also can act as a feedstock to be further converted into butanol, a biofuel. Butanol is often referred to as a “drop-in fuel” because it can be directly substituted for fossil fuels without the need for costly engine modifications.
The biocatalysts generated from the CBM well microbes demonstrated other unique properties. Researchers found they possessed exceptional versatility and could also convert carbon monoxide, formate and methanol feedstocks to bio-acetate.
Work is underway to scale up the production of the new biocatalysts by adding yeast, nitrogen and other nutrients and enriching the biocatalysts in reactors. Experiments focused on temperature and other variables to optimize operating parameters have been completed.
Additional work is focused on DNA sequencing to better understand and characterize the microbes from the CBM well. The results of the sequencing will help the team identify microbes with similar properties and capabilities.
The use and development of biocatalysts is an area of NETL expertise. “We have characterized microbes from coalbed formation water, shale gas production fluid and other sources, so we recognized the CBM well microbes would provide a good base to develop an effective biocatalyst,” Gulliver said.
Researchers also needed to determine how the versatile biocatalysts will fit in the marketplace. To answer that question, NETL completed a techno-economic analysis that found the biocatalyst’s adaptability to convert a variety of feedstocks or a feedstock with mixed carbon compounds to useful products fills an important market need.
Other projects undertaken by Gulliver and her team focus on understanding how microbes in the subsurface affect the porosity and permeability of rock layers when CO2 is injected into deep underground storage reservoirs.
According to Gulliver, the development of biocatalysts to convert greenhouse gas into useful products is essential to building a well-rounded strategy to lower atmospheric levels of carbon.
“We need to take a diverse approach to reach the nation’s goals calling for net-zero carbon emissions in the power sector by 2035 and the broader economy by 2050,” Gulliver said.
“Long-term carbon sequestration in subsurface reservoirs is critical to address climate change. But the development of biocatalysts to convert carbon to useful products that can be sold needs to be a meaningful part of the equation to meet our decarbonization goals and help offset the costs of carbon sequestration,” she said.