Indiana University Research & Creative Activity January 1998 Volume XX Number 3


There's No Fuel Like an Old Fuel
Searching for New Energy in Indiana Coal Beds
by Deborah Galyan

Maria Mastalerz remembers Christmas break 1996, not so much for its holiday cheer, perhaps, as for the unusual contents of her bathtub. It contained a number of steel cylinders. The cylinders contained coal samples she had taken from boreholes in southern Indiana, and the coal was emitting methane gas. Mastalerz, a coal geologist/sedimentologist at the Indiana Geological Survey, Indiana University Bloomington, recalls getting up once an hour every hour throughout the night to attend to them. She had to measure the amount of gas rising from the coal at regular intervals--every ten minutes initially, then every hour, and finally every twelve hours, Christmas or not--until the emissions stopped. "Even my daughter and husband were up measuring gas," Mastalerz says. "It does require a lot of attention."coalaxes

Measuring methane in coal samples can help determine whether it might be transformed into a new commercial source of gas for Indiana, and it is the nuts-and bolts portion of one of Mastalerz's many energy-centered projects. In addition to her work at the Indiana Geological Survey (IGS), Mastalerz holds an academic appointment to the faculty of the University Graduate School. "I find that my applied and academic research overlap very nicely. I'm interested in a lot of basic questions about coal, but right now, I feel that my major allegiance is to the Indiana taxpayers through IGS," she says. "When I'm doing applied research, I can almost always find something of academic interest." Mastalerz began her geology career in the 1980s in her native Poland, earning a Ph.D. in mining geology while doing research in the Walbrzych Coal Basin in southwest Poland. She studied the chemistry and petrography of coals (the latter uses a reflected-light microscope to view highly polished samples of coal), and she examined the petrology and geochemistry of oil shales as a postdoctoral fellow at the University of British Columbia before joining Indiana University Bloomington in 1994.

Mastalerz works on the pragmatic end of the energy research continuum. As the millennium approaches, interest in renewable energy sources and radically new technologies continues to grow, yet the majority of energy consumed in the United States comes from nonrenewable fossil fuels. Given this reality, Mastalerz and a number of her Geological Survey colleagues remain interested in coal, in its geological history and physical characteristics, and in its ongoing ability to supply energy at low costs. "Coal has been with us for a long time, and there is plenty of it left to last for several generations. That's somewhere between 100 and 200 years of reasonably good, accessible coal for the future," Mastalerz explains. "There's no question that this coal will be used."

Today, the Department of Energy estimates that the United States possesses nearly 31 percent of the world's known recoverable coal reserves. Despite an increasing concern about the deleterious effects of its combustion on the environment, coal continues to occupy the second largest American market share for fuel, behind only petroleum. Geologists have long played a role in commercial coal exploration because of the sorts of questions they ask: How did coal form? What kinds of vegetation contributed to the development of gargantuan peat swamps in the Carboniferous and Permian periods--spans of time ranging from 340 million years to 240 million years ago--from which we now mine nearly all coal? What kinds of biochemical factors led to the initial stage of coal formation--known as peatification--in those swamps? How were geochemical factors such as temperature, pressure, and time involved in the formation of various ranks of coal?

CoalcartThese questions interest Mastalerz and other geologists for their pure research value, but the answers contain information vital to the coal industry. Such basic research has led to useful ranking and grading systems through which the fuel is classified according to its increasing "coalification." The lowest rank, lignite, often contains fragments of original plant remains, is moister, and burns less efficiently than harder coals, resulting in the lowest heating value. Bituminous coals are denser and produce higher heating values suitable for industrial combustion. A hard, lustrous coal called anthracite ranks highest due to its high carbon content. A walk around the Bloomington campus heating plant would yield a firsthand look at mostly bituminous coals and a sense of just how much is needed to provide heat and hot water to the campus: an average of 60,000 tons of Indiana coal a year, according to Rick Cross, physical plant manager.

Ongoing study of the ancient conditions and processes that led to coal formation has enabled geologists to develop and refine a predictive model for locating coal with specific qualifications. "For geologists and miners, the age of coal discovery is basically over," Mastalerz explains. "We now know where the coal basins are. There are few places left in the world where exploration for major resources has not already taken place. In Europe, for example, I think we have looked at the same rocks two, maybe three times. We know where to dig. Now the question is 'Which coal should we dig to get properties most desired for specific applications?'"

Like many of her research projects, Mastalerz's methane studies reflect changing priorities in energy policy in the United States and other developed nations. International politics, environmental legislation, and economic concerns each play a major role in focusing geology research. Both the Clean Air Act of 1990 and the Energy Policy Act of 1992 have significantly hurt Indiana's coal industry. These laws use tax incentives and fines to urge industries and utilities to alter their current operations in favor of cleaner, more efficient energy sources. Throughout the '90s, deadlines for various stages of compliance with the Clean Air Act put increasing pressure on Indiana power plants and coal-burning industries to reduce sulfur trace elements and particulate emissions. Indiana coal quickly developed a "bad reputation" due to its high sulfur content.

"Most of the coal in Indiana is 2 or 3 percent sulfur. 'Good coal,' that is, the kind utilities prefer to buy now, has less than 1 percent sulfur," Mastalerz explains. "Trace elements in coal are also a hot topic these days. It turns out that high-sulfur coal is often associated with high levels of hazardous trace elements, such as mercury, selenium, chlorine, and arsenic." As a result, coal production in Indiana dropped from 36 million tons to 26 million tons between 1990 and 1995, as many coal powered utilities opted for the simplest, cheapest solution: they switched to "good" low-sulfur coals from Wyoming and Montana. "Utilities will be buying Western coal for a long time," Mastalerz says. "There is probably a hundred years' worth of minable, low-sulfur coal out West. And while it lasts, production of high-sulfur coal will inevitably decline."

But the future isn't entirely grim for Indiana coal. "For one thing, utilities in the Midwest have designed and developed combustion technology that works best with Midwestern coal," Mastalerz explains. "Burners are designed to burn coal at specific pressures and temperatures per unit of weight. Western coal generally burns at a lower Btu (British thermal units), so Midwestern utilities often find that Western coal will not burn as efficiently in their equipment. It's not so easy to switch." Another trade-off is shipping cost: in the interest of increasing their market share, Western coal producers have kept shipping costs artificially low, but Mastalerz believes these costs will rise eventually. Another development encouraging to Indiana coal producers is the increasing popularity of an anti-pollution technology called "wet scrubbing." Wet scrubbing enables utilities to burn high-sulfur coal while simultaneously scrubbing sulfur dioxide gas out of the plant's smokestacks to keep it out of the air. These scrubbers are expensive to install, but cost-effective in the long term. "Given these various factors," Mastalerz says, "I believe we will continue to use Indiana coal at a rate of at least about 20 million tons a year."

Mastalerz and others at the Indiana Geological Survey use a variety of microscopic and chemical analytical techniques to help local coal companies locate the cleanest possible coals, while also exploring new applications for the state's high-sulfur reserves. "This is where our technical expertise as geologists comes in to play," Mastalerz explains. "We are able to perform various types of analyses to understand the precise composition of coals. We can identify which coals contain the least amount of sulfur, the least amount of ash, and harmful trace elements. Without such analyses, coal companies would be drilling at random. Exploratory drilling is very expensive, but we can help reduce costs dramatically in the exploration phase of coal production."

Mastalerz travels to coal mines around the state usually once or twice a month to take coal samples for her various projects. In standard coal petrographic analysis, samples are crushed into a small size--a messy endeavor, according to Mastalerz's coal-coated student assistant. The researchers then embed small amounts of crushed coal in resin to form small pellets. They label, grind, and polish the pellets in a five- to six-step process that provides an optimal surface for reflected light microscopy. Then Mastalerz and her student assistants examine 500 different points on each coal sample, identifying macerals (microscopically distinguishable organic components) such as vitrinite (wood material), resins, spores, cuticles (leaf material), and mineral matter such as pyrite and clay. The coalification level (rank) is commonly determined by "vitrinite reflectance." Reflectance is a measure of the intensity of light reflected from the polished surface of a vitrinite maceral; in simple terms, it can be described as brightness. "Because woody material or 'vitrinite,' is the major component in coal and can be easily identified, it was selected as a measure for rank determinations," she says. "Such a technique creates a standard way of determining how advanced the coalification process is in a given coal--a way of describing how aromatic and reactive the coal is," Mastalerz explains. "Vitrinite reflectance increases in coals of higher rank because they have undergone more extensive physical and chemical changes due to exposure to higher temperatures, pressure or both."

Mastalerz also measures and describes other characteristics, including trace element composition and calorific value, which determines how much heat a particular coal can generate. "Many factors influence coal quality," Mastalerz explains. "We need to understand both the biochemical and geochemical processes that contributed to its formation. There's a lot of chemistry involved."

Mastalerz uses this microscope-based methodology in most of her research, including her studies on methane, but determining the amount of gas in a particular sample requires more than standard coal-rank analysis. Her work on the potential of coal-bed methane to provide a new source of energy illustrates how geologists often take the initiative to explore innovative solutions to problems in a field where industry has been reluctant to change. "The coal industry has always been somewhat conservative. They have methods and techniques that they've used for years, in some cases for centuries, and they are resistant to change," Mastalerz says. "I think coal companies don't always understand how much geologists can offer to their industry. But I have to say that, in Indiana, we have a good working relationship with the local coal industry. We are working on a number of joint projects, and I'm pleased to see it because I think this partnership is the most effective way to work."

Mastalerz began to study methane quantities in Indiana coal beds after observing the successes Alabama and New Mexico have had in extracting large quantities of methane from coal basins for commercial use. In the last decade, researchers have determined that many coals generate the gas. Methane is formed as a by-product of the chemical and physical changes that create coal. "Gas from coal is a newly discovered resource," Mastalerz explains, "only a little more than a decade old. Studies on coal-bed gas are taking place all over the world, but, as of now, the U.S. is still the only country commercially exploiting coal-bed methane." Coal-bed gas is commonly almost pure methane, cleaner than coal, and it can burn in conventional methane furnaces--meaning that the cost of retrofitting existing combustion equipment would be low.

In addition to its attractive economics, methane found in coal beds has a unique characteristic that distinguishes it from natural gas: it can be far easier to locate. "Coal is porous, and because the pores it contains are usually very small, the gas remains trapped in these pores until the coal is extracted," Mastalerz explains. "Natural gas associated with petroleum doesn't stay at its generative source, it migrates until it is trapped in a reservoir. And we have to find those traps in order to capture it. Coal-bed gas is special because the coal is both the source and the reservoir." Coal-bed methane must be captured underground, before the coal is mined. "As it is now, Indiana coal is mined, then stored above ground until it is sold, during which time any gas contained in the coal escapes," Mastalerz says. "Unfortunately, we are losing this resource if it is viable."

The first step in the project for Mastalerz and fellow geologist Eric Kvale, a research scientist at the Geological Survey, is to determine how much coal-bed gas is available in Indiana. This is why Mastalerz found herself hovering over a bathtub full of coal samples one Christmas. "We usually just measure in the lab," she says, laughing. "But we did some drilling around Christmas. That's just the way it happens sometimes."

Using samples taken from specific coal seams, Mastalerz measures the gas at regular intervals as it escapes from sealed canisters into a gas displacement apparatus. The process often takes several months, until the gas is completely depleted. Finally, she weighs the coal. "Once we know how much the coal weighs and how much gas was desorbed from this coal, we can calculate how much gas (per volume) is contained in one ton of coal. And, given that we know how thick a particular coal seam is, we can estimate the amount of gas in a specific area."

Mastalerz emphasizes that her current work on coal-bed methane is preliminary. "Our primary goal is to document areas where gas exists and can be easily extracted and commercially used. We are still asking basic questions, like: 'Is there enough?' and 'Can we get it out of the coal?'" If and when Mastalerz determines that enough methane exists in a particular coal bed to support a commercial venture, the next stage will be to discover how difficult the gas is to recover. That depends largely upon the permeability of the coal in a given seam. "We understand that the more permeable a coal is, the more gas can be recovered," she says. "But many coals are impermeable, and while there may be large quantities of gas in these coals, the difficulty of extracting gas from them makes the process impractical."

Mastalerz is cautiously optimistic that coal-bed methane will exist in large, easily extractable quantities in Indiana. "I have to say that, if you apply general rules for finding gas in coal, you wouldn't expect to find a lot of gas here. But no one has looked," she says. "I expect that we will find useful amounts of gas. There are many factors to consider, but I am optimistic. If our preliminary findings are positive, we will begin to ask more detailed questions like, 'Where are the largest quantities of gas?' 'Why is it here, but not there?' 'What is the best method of extraction?'"

The project is generating much interest from coal companies with underground mines. They stand to profit from selling not only the methane, but the coal from which it is extracted. One company has provided drilling and analysis to support the project. "This study could result in an economic windfall for Indiana," Mastalerz says. "Imagine if Indiana's troubled mining companies were suddenly handed a clean, new, commercial energy source, one that they barely even knew existed five years ago? It would mean, among other things, that the companies could lower the price of Indiana coal, which is very expensive these days compared to Western coals. This is what you would call a 'win-win' situation."

Mastalerz enjoys her trips deep into the heart of Indiana's coal mining area to take samples. "I've been doing it pretty much all my life," she explains. While working on her Ph.D. in Gliwice, Poland, she enjoyed collecting samples and exploring coal mines, some of them as deep as 2,100 feet beneath the surface. "That's what geology is about," she says. "It's important to go to the field and see things the way they are in the world before you analyze them in the lab. I've always loved seeing the big picture." E



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