DENVER, CO (April 28, 2005): Luca Technologies LLC today announced that its researchers have confirmed the presence of a resident, methane-generating community of microorganisms ("microbial consortium") in substrate samples taken from the 110,000 acre Monument Butte oilfield located in North Eastern Utah. This site represents the latest in a series of active "GeobioreactorsTM" that Luca Technologies has identified since its first demonstration of this phenomenon in the Powder River Basin coalfields of Wyoming. Geobioreactors are sites where microbial conversion of underground hydrocarbon deposits (oil, oil shales, and coal) to methane is ongoing. Such Geobioreactors may offer the potential of turning currently finite energy reserves into methane "farms" capable of long-term, sustainable energy generation.
"The hydrocarbon resources available in the Monument Butte oilfield are very large, making the possibility of shifting from oil production to the ongoing farming of clean, natural gas an attractive consideration," said Robert Pfeiffer, president and chief executive officer of Luca Technologies. He noted that the Monument Butte site was one of six oil fields across the United States that Luca has been studying. The company has demonstrated two of those sites to be robust, methane-generating Geobioreactors, and two to be less actively generating methane. Three additional sites are not currently active but may have the potential to be turned into active Geobioreactors through cross-inoculation with microbial consortia from active sites.
Luca scientists have also begun to isolate and identify particular members of the Monument Butte microbial consortium. Through partial DNA sequence analysis, the company has identified Clostridia and Thermatoga as two of the key members of this consortium. Clostridia form a broad genus of bacteria known for their diverse metabolic pathways. Clostridia frequently thrive in anaerobic environments and many species are known for their heat tolerance. Thermatoga microorganisms are known to play a role in the anaerobic oxidation of hydrocarbons to alcohols, organic acids and carbon dioxide. Thermatoga also thrive in high temperature environments, such as those found in sub-surface oil wells.
"Oil within the Monument Butte field has a waxy composition that may facilitate the strong real-time methane generation we see at this site," commented Mr. Pfeiffer. "If so, then areas with large accumulations of waxy oil – for example, the Daqing Field in Northeast China -- could prove to be important sites for the bioconversion of residual oil to methane and the restoration of these 'spent' sites to economic energy production."
Note that oxygen suppresses the methane generation.
Luca scientists, employing the tools of modern biotechnology and genomics, have now shown that living methane generating, microbial consortia are present and actively forming methane within some of these hydrocarbon substrates. In addition to demonstrating that methane formation by these microbes can be stimulated by the introduction of nutrients or suppressed by heat sterilization or the introduction of oxygen, Luca has shown that radio-labeled CO2 (carbon dioxide) introduced to these substrate samples is converted to radio-labeled methane. This demonstrates that the methane formation is the result of a biological process occurring today.
Luca has a more detailed paper on their web site about this report. (PDF format)
Because their environment is hostile to familiar forms of surface life, oil reservoirs were originally thought to be devoid of life. However, more recent research has revealed that many oil reserves contain a variety of active and diverse microorganisms (19). In general, these microorganisms have been studied in the context of fouling, souring, and degradation of oil 8 reservoirs. Various gases are frequently associated with oil wells, and Luca’s data indicate that methanogenesis, the creation of methane, is another biological process occurring in some oil reservoirs. In addition to identifying these active systems (Geobioreactors), it will be important to understand the variables that control this overall methanogenic process.Because oil is a liquid, it is likely to be an easier substrate for the microbial consortia to contact, biodegrade, and convert to methane compared to solid-phase substrates such as coal and the kerogen in shale. Biodegradation is carried out by the consortia, and it has been shown that a mixed group of microorganisms is more effective at biodegrading organic compounds than any of the component strains acting alone (5). These microorganisms utilize the hydrocarbons as both a carbon and energy source, and the process most likely takes place at the oil/water interface (13). The enzymatic diversity within these microorganisms required to carry out the myriad of metabolic steps involved in methanogenesis is extensive. The ability to influence and control these microbial reactions in situ has major economic implications.
Back in November 2004 Luca Technologies claimed to have found methane generating bacteria in the coal deposits of Wyoming's Powder River Basin. At the time of that previous report another blogger asked me if I thought this report could lead to a practical way to extract large amounts of methane from coal. My initial reaction was that injection of bacteria into coal beds would be very problematic because the bacteria would not diffuse rapidly through solid masses. The amount of drilling needed to get good diffusion of the bacteria might result in costs too hgh to make such an approach economically feasible. Well, in their latest report they specifically note that getting bacteria into contact with liquid oil is easier than getting it into contact with solid coal.
Of course coal is much more plentiful than oil. But old and heavily depleted oil fields which have a lot of inaccessible oil left which injected bacteria might reach. If bacteria injected could reach those oil left-overs then bacterial injection might become an economically viable way to extract otherwise unreachable energy.
The November 2004 report is also online and Luca points out that if even a small percentage of a coal field's coal could be converted to natural gas in situ then the amount of natural gas that could be produced would be substantial.
The primary goals of the research were to evaluate the recent and ongoing biogenic methane formation in PRB coal seams and to identify some of the variables that may affect the creation of biogenic gas in these coals. The sheer size of the PRB coal-bed resource as substrate for biogenic methane creation is the primary incentive. The coalbeds of the PRB are thought to contain ~580 billion tons of coal in contiguous seams at least 20 feet thick (DeBruin et. al, 2001). Only a small portion of this coal is accessible for domestic use via mining. Although substantial quantities of methane exist in the PRB coal seams (estimated total resource of ~37 TCF, DeBruin et. al, 2001), this quantity of gas likely represents a small fraction of the methane that could be created through biogenesis supported by hydrocarbon substrates within the coals. For instance, the conversion of only 1% of the known PRB coal resource above would generate approximately 86 TCF of gas (Luca estimation).
So how much as 86 trillion cubic feet of natural gas worth? Natural gas is priced in dollars per thousand cubic feet with a general upward trend in natural gas prices now putting natural gas at the wellhead at about $5 per thousand cubic feet. If we assume $5 per thousand cubic feet then conversion of 1% of the Powder River Basin coal into natural gas yields a market value of about $430 billion. Bacteria suddenly become fascinating little creatures.
As of December 31, 2002, the estimated U.S. total proved reserves of natural gas were at 183.46 trillion cubic feet (tcf).
Natural gas consumption reached 22.6 trillion cubic feet (tcf) in 2000, a four percent increase over the previous year.
Natural gas supply, consumption, and imports are projected to steadily expand, with consumption projected at 35 tcf in 2025.
Current worldwide natural gas resources are about 13,000 tcf and natural gas reserves are about 5,000 tcf.
Global estimates place the gas volume resident in oceanic natural gas deposits in the range of 30,000 to 49,100,000 tcf, and in continental natural gas hydrate deposits in the range of 5,000 to 12,000,000 tcf.
World production of natural gas is dominated by the United States (24 tcf) and Russia (21 tcf), whose combined gross production accounts for 45 percent of the 102 tcf produced in 1998.
Aside: While some more recent estimates of oceanic clathrate gas deposits put the numbers way lower if we could ever get at the clathrates economically then CO2 emissions could rise so high we really would melt the polar ice caps.
At a 1% conversion efficiency then Luca's process might be able to extract an amount of natural gas from a coal field that equals 47% of current US natural gas reserves. A practical proposition? Imagine drilling down vertically to a coal seam and then drilling horizontally into the coal seam many times at places spaced apart so that all coal would be in reach of water and bactera sent down into the drill holes. Could this be done cost effectively? Or would the distance between drill holes have to be only a few inches due to lack of ability of the bacteria to migrate very far away from the drill holes? Also, if the holes couldn't be kept full of water oxygen exposure might stop the anaerobic process of methane production in the bacteria. So pumping of pure nitrogen gas into the holes might be necessary as a way to keep the oxygen out.
Any readers know enough about coal drilling costs and about water diffusion in coal to take a stab at guessing about the economic viability of such an undertaking? Also, assuming a 1% conversion efficiency due to diffusion problems what volume amount of coal would contain 100 times the energy of 1 trillion cubic feet of natural gas? My guess is one would be better off drilling more thoroughly into a smaller area in order to get a conversion efficiency much higher than 1%. But maybe that would require something akin to converting the coal to powder to even make that work Such an effort to turn coal into powder underground might be too costly. Just guessing though.
|Share |||Randall Parker, 2005 April 28 08:39 PM Energy Fossil Fuels|