Researchers say deep coal energy extraction possible
Anyone connected with the coal business knows that all mines contain coal that is not retrievable. Either it is located in a place that is difficult to reach or nature placed it in veins that are too thin to mine economically.
Such people know, too, that much more coal lies far below levels that are currently mined. While present mines are deep compared to those of a hundred years ago, and remote mining equipment is being developed to mine even deeper, technologically, it may be impossible even for robots to mine coal that is too deep.
However, University of Utah researchers visited Carbon County last week to meet with energy officials to explain a way that they believe coal can give up its energy without ever being seen by a human face or one of humankind's machines.
"We have been looking at these problems of deep coal in different ways," said Mike Nelson, a research professor at Utah. "Do we really need to get the black rock out of the hole to get the energy out of it? Could we somehow turn it into energy, remove that energy and leave the residual behind?"
The research team's objectives have included using innovative mining technologies, C02 or gas injection, fracture technology and methogenic microbes to recover methane from coal seams. Their presentation last week focused, however, on using microbes to help coal bed seams yield more methane.
For years, gas companies have pulled methane off coal veins and delivered it to customers. However, once those wells are in production, their decrease in productivity is fairly rapid with levels of 20 percent of initial production occurring shortly after putting the operation into gear. However, more of the resource remains even after a well is shut down.
But the Utah researchers say that, considering the knowledge they have acquired about microbial production, slower production methods could be a thing of the past.
"Right now gas companies are relying on C02 and nitrogen to help extract more methane from fields that are dropping in production," stated Jack Adams, a research professor. "But microbes could be used to release even more gas in those levels and at a deep level [that] would allow us to bring out gas by creating an optimal environment for methane production."
According to the researchers, it is very hard for methane to flow off deep coal veins. Pressures of the earth at that deep level lessen the flow, so the pressure needs to be released and the surface area of coal veins expanded.
The researchers also suggested that the use of an energy production system and the subsequent capture of carbon-emitted gases could possibly solve the problem of greenhouse gases that is presently a prominent point of discussion in environmental circles concerning the use of carbon-based power sources. In other words, the researchers say they have been evaluating concepts for carbon-neutral power generation. In fact, the use of C02 injected back into the ground would provide extra nutrients for the microbes being used to extract more methane.
"We see a way for a power plant to draw methane from the ground using this process, creating electricity while sequestering the C02 it produces in one looped process," said Adams.
The group showed a simple diagram of how such a process would work.
Adams also pointed out that the microbes that would be used are tough and can be used under a variety of circumstances.
According to the researchers, the microbes will work well to produce methane in poor quality water and work even in areas where there is no oxygen. In addition, temperature in the coal veins would not be a problem, either. The microbes that would be used could survive in freezing temperatures up to 80 degrees above zero.
The path to their goal is to demonstrate and understand biogenic methane production from coal samples in varying conditions in the laboratory, examine the mechanisms to further optimize methane production rates and process economics in the lab (evaluating t ambient and elevated temperatures and pressures), test the laboratory prototype and conduct a field demonstration.
The researchers came to Carbon County looking for possible partners to work with on some of these test projects.
"Coal is the largest fossil fuel reserve on earth," said Jack Hamilton, program manager for the project. "We're hoping to find some people to work with to see if this will work in a field test."