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March/April 2009
Feature

The Challenges of Coal

D05 Addresses New Coal Technologies

A century old ASTM International committee considers today’s issues in current standards work.

When we charge up our future electric cars, most of us will burn coal to power them — just as we already do whenever we run our computers, flick a light switch or turn on our television sets. Nearly 50 percent of our electricity is generated by coal, and that demand is expected to increase 30 percent by 2030.

Coal is the other fossil fuel, promising to supersede oil as petroleum supplies dwindle and solar and other alternatives plug part of the future energy gap. But coal comes with a potentially hefty environmental price. According to the Intergovernmental Panel on Climate Change, the increased use of coal and the resultant release of carbon dioxide and methane — both greenhouse gases — have contributed significantly to global warning and climate change.

So, how do we reconcile our need for coal as a viable and domestically plentiful alternative to oil with our equally important need to use it in a sustainable way that minimizes environmental harm?

The German Vattenfall pilot plant has been constructed to validate and improve methods for capturing carbon dioxide from coal-fired energy production processes.

A Century of Standards

Helping to solve coal’s challenge is ASTM Committee D05 on Coal and Coke. For more than 100 years, the committee has worked with the coal, utility and steel industries to provide standards for classifying, sampling and analyzing coal. Initially, D05’s standards resulted in technological, economic, productivity and pollution-reduction benefits. But, with widespread concerns about global warming, reinforced by the adoption of the Kyoto Protocol in December 1997, the committee is now taking a closer look at coal’s environmental footprint plus opportunities to develop standards that promote new coal technologies. Those ongoing efforts were bolstered in October 2005 when NESHAP (National Emission Standards for Hazardous Air Pollutants) for Industrial, Commercial, and Institutional Boilers and Process Heaters adopted Committee D05 measurement methods for determining compliance with federal emission regulations. Still, work continues.

As Louis Janke, president of Quality Associates International Ltd., Douglas, Ontario, Canada, and veteran ASTM member, explains, “I’ve come to the full realization that there isn’t a standard that’s going to be revised or find its way into our books that isn’t going to consider sustainability — and by that I mean its impact on our quality of life.”

Measuring Carbon Content

One example of the potentially significant environmental impact of Committee D05’s work is revised standard D5373, Test Methods for Instrumental Determination of Carbon, Hydrogen and Nitrogen in Laboratory Samples of Coal, published in February 2008. The standard could affect the analysis of coal worldwide and subsequent carbon dioxide emissions if universally embraced. According to D05 chair John Riley, Ph.D., professor emeritus, Western Kentucky University, Bowling Green, Ky., “D5373 is the best standard in the world and a huge improvement over the first version of the standard.” But it took some work to get there.

In the mid-1990s, engineers at coal-burning electrical generating plants all around the world were wondering why they saw discrepancies between their predictive heat values — or the amount of electricity that they expected to generate — and the actual plant rate. They found that even when engineers at different plants tested the same coal for carbon and other elements, they had different results. More alarming, those engineers also had different results when testing pure substances, laboratory samples specially prepared to contain the same substances. Because measuring the carbon in coal is essential for predicting the amount of carbon dioxide emissions it will create when burned, there was a clear need for a standard that delivered accurate, repeatable results.

Janke explains, “You can’t negotiate emissions standards if you don’t have a reliable way of measuring emissions.”

To address this need, Janke organized an international control study, eventually developing the revised standard, which instructs engineers at coal-fired power generating plants how to use pure substances to calibrate their instrumental analyzers. That way, they can determine more accurate heat values as well as carbon content and carbon dioxide emissions, features that also make the standard useful to governmental and other entities concerned with the environmental impact of burning coal.

“The revised standard forces us to be honest about emissions and encourages more efficient use of coals that are appropriate for their end product,” says Janke.

Natural Gas from Coal

A proposed D05 standard, WK8750, Practice for Determination of Gas Content of Coal — Direct Desorption Method, addresses the amount of natural gas, also referred to as methane or unconventional natural gas, in coal beds. As a greenhouse gas, methane contributes 21 times as much to global warming as carbon dioxide. It’s also volatile, fueling explosions and fires in coal mines. WK8750 could have the combined effects of helping energy producers recover a useful and plentiful fuel, control greenhouse gas emissions and make coal mining operations safer.

Coal beds in the United States contain an estimated 30 to 604 trillion cubic feet (1 to 17 trillion cubic meters) of recoverable methane. In the last 15 to 20 years, coal bed methane has grown to account for some seven to 10 percent of total natural gas production in the U.S., and it’s likely to increase as large fields of natural gas are depleted and producers drill for gas in the coal fields of Wyoming’s Powder River Basin, the San Juan Basin in New Mexico and Colorado, the Warrior Basin in Alabama and in fields along the Rocky Mountains, Gulf Coast and in the Midwestern states. Overseas, China and Australia are also known to have large reserves of coal bed methane.

Currently, there are two methods for determining the viability of recovering coal bed methane in a particular area or region. One is an indirect method that makes inferences from available geological information. The other, advocated by the proposed standard, uses the direct desorption method where a core of coal is extracted from a deposit and put in a sealed container. Measuring the amount of gas released from the core over time determines how much natural gas is contained in a coal bed.

Peter Warwick, research geologist with the U.S. Geological Survey, Reston, Va., and technical contact for the task group, explains, “Determining whether a coal deposit is a viable source of natural gas in advance of mining leads producers to use coal deposits more efficiently.”

A draft of the proposed standard is expected to be ready for review this spring. Once approved by ASTM, it is hoped that the standard will be adopted internationally.

Standards for New Coal Technologies

In the spirit of recognizing the coal industry’s evolving needs, Committee D05 has formed a technical planning group to consider opportunities for standards that promote alternative uses for coal and consider existing standards in new ways.

For instance, the revised D5373 standard, says Janke, could also be used “as an initial screening tool for hydrogen and nitrogen to indicate whether a certain type of coal is appropriate for more advanced coal technologies such as coal gasification or liquefication,” where coal is processed into fuels like gasoline and diesel.

Integrated gasification combined-cycle power plants that remove harmful materials from coal before burning it may require new measurement standards. The plants operate more efficiently and with lower emissions than conventional power plants. “It’s better to remove hazardous elements before combusting them because that potentially makes it easier to dispose of them or convert them to a form that might have some other use,” notes Jay Albert, technical director at Parr Instrument Co., Moline, Ill., and a member of the group working on WK8750. “If we determine how to extract hazardous elements at the most appropriate time in the energy-production cycle, the environmental impact can be much less.”

There are also opportunities to develop new standards in areas where coal is mixed with other fuels such as biomass, biodiesel and briquetted biomass fuels. For example, a Chinese organization recently submitted a draft of a new standard for testing sulfur-fixing briquettes for domestic heating and cooking. The briquettes, which are composed of high sulfur coal, plant and wood materials, and a sulfur-fixing agent, prevent sulfur from becoming sulfur dioxide when burned, thereby reducing the harmful environmental impact of acid rain.

Making Coal Clean

But can coal ever be really green or is “clean coal” truly an oxymoron?

Former D05 chair and current ASTM board of directors member James Luppens, project chief, U.S. Coal Assessment, U.S. Geological Survey, says, “Coal utilization is getting cleaner all the time, but there’s no free lunch. It’s still a fossil fuel.”

Janke believes that the coal-burning industry “will refurbish itself in relation to generation capacity. It will become learner and meaner, using less coal to generate more power. But the real challenge will be to use carbon dioxide emissions in a positive way.”

For Riley, improvements in the sustainable use of coal ultimately come back to respecting standards. “If we use standards, we have a better understanding of the coal we’re using and how we’re using it, and that leads to more efficient use.”

 

Adele Bassett is a Media, Pa.-based freelance writer who has covered everything from youth gangs in Colorado to earthquakes in C onnecticut while working for a variety of corporations and publications. She holds a B.A. in English, an M.S. in journalism and an M.B.A.