Coal Hazards and Research Needs

Fuels of all types create adverse environmental effects in every part of the production—consumption cycle: extraction, upgrading, transportation, conversion, and utilization. The nature and type of the environmental impact varies with the fuel, but coal is by far the most potentially polluting of them all. Thus, a doubling of the use of coal—which is proposed by President Carter—could create very large adverse environmental effects, such as those identified below, if the best available control technology is not used.

Surface mining can produce not only land damage and adverse aesthetic effects, but can pollute streams by deposition of silt and the discharge of acid mine water. Underground mining causes subsidence, and while its effects on land are not as visible as those of strip mining, they can be major and long-lasting. During the past year the president signed a strip-mining bill aimed at reclaiming land that was disturbed by surface mining in the past and at preventing land damage from current surface mining operations.

Coal preparation plants also are a source of pollution. Air pollution results from the sulfur oxides and particulates emitted during coal drying. The discharge of water used to clean the coal can cause pollution. Solid wastes are removed from the coal during washing and these are normally stored above ground. They are a potential source of air and water pollution when the piles are leached by rainwater.

The environmental impacts of coal conversion processes have probably received the major attention of those concerned with preserving environmental quality. Air pollutants arising from the combustion of coal include sulfur oxides, nitrogen oxides, particulates, carbon monoxide, and small amounts of hydrocarbons and heavy metals. Water pollution is caused also by the chemical additives that are used to prevent corrosion and by hot water. Solid wastes, in the form of ash or sludge from sulfur oxide scrubbers, must also be disposed of. About 20 percent of the coal mined in the United States is used to make coke, and coke oven plants are one of the most polluting of all industrial processes. As new processes for converting coal to synthetic gaseous or liquid fuels become commercial, a new set of potential environmental effects will be created. And in the long run, the climatic impact of a large increase in coal burning will have to be taken into account. Two issues of particular concern are discussed below.

Climatic effects. The growing use of fossil fuels, which started a century ago with the industrial revolution, has caused the carbon dioxide content of the air to increase.

In July 1977, the National Academy of Sciences released a report entitled Energy and Climate. Two aspects of this study are of major importance. First, the report states that there is no reason as yet, from a climatic viewpoint, to be concerned about the utilization of coal (or other fossil fuels) at least over a period of a few decades. Nevertheless, a judgment about the climatic impacts of fossil fuel utilization will have to be made soon enough to ensure that other sources of energy will be developed if the carbon dioxide "greenhouse" effect appears to be a large problem. It should be noted that this is a global, not just a U.S. problem. Currently, the United States contributes only about 27 percent of the carbon dioxide produced by combustion of fuel and this share is likely to decline to approximately 10 percent by the year 2000.

The second conclusion of the report is that "there are profound uncertainties about the carbon cycle, climate and their interdependence." The report, states that "these uncertainties can be resolved only by a well-coordinated effort of a profound interdisciplinary character." It then recommends that a comprehensive research program be undertaken now and continued over the next several decades to resolve these problems. Making the right decision in such a context of persistent uncertainty will demand a great deal of wisdom and luck.

Sulfur oxides. An environmental problem of more immediate interest relates to the control of sulfur oxide emissions from coal combustion. This issue has been under debate and consideration now for nearly fifteen years, but major problems about the state of control technology still remain. At present, about twenty-five flue gas scrubbers are in operation, covering about 3 percent of all coal-fired electric utility capacity.

In addition to the scrubbers now in operation, about twice as much capacity is under construction and much more capacity is planned. Although lime and limestone scrubbers represent 90 percent of all capacity in operation, and most of that under construction, a number of the plants that are being planned intend to use some type of regenerable scrubbing process that creates a useful by-product instead of a waste. Even after a decade of use, lime and limestone scrubbers continue to be less reliable than the electric utility companies would like.

The federal budget for sulfur oxide research will decline in 1978 but a very large supplemental budget increase has been requested in order to study second generation scrubbing technologies. The development of advanced technologies, most of which would recover the sulfur in the coal instead of throwing it away in the limestone sludge, should have high priority. However, there is a rub: unless new uses are found for sulfur, recovering all of the sulfur would result in a glut of sulfur on the market. For this reason, additional methods of disposing of the sludge from "throwaway processes" must continue to receive attention.

Additional issues. Another problem related to coal is the loss of fine particles in the air during transportation. Approximately 50 percent of all coal is moved by rail, with the rest being transported by river (16 percent), ship (6 percent), truck (12 percent), and other means (16 percent). Under some circumstances coal could be shipped by slurry pipeline at a lower cost than if other transport modes were used. However, while coal slurry pipelines have less adverse environmental effects than conventional coal transport methods, they require the use of relatively large volumes of water. This could cause problems in water-short coal producing areas, such as Wyoming. It certainly would not be a welcome development in the western coal areas. The problem could be resolved if the water were returned to the source after it was separated from the coal at the discharge end. The added cost would be about 40 percent.

The National Energy Plan projects coal consumption to double between 1976 and 1985, from 660 million to 1.3 billion tons per year with consumption by industry other than utilities increasing more than 2.5 times. This can occur only if much of the existing industrial capacity is shifted to coal from oil and gas, if nearly all of the new capacity that will be constructed is designed to use coal. Such developments could cause serious adverse environmental impacts unless provisions are made to prevent them. Doubling coal production would require massive land reclamation efforts if adverse effects on the land are to be avoided. New rail systems and equipment will be needed and their construction could have major adverse environmental effects.

The most troublesome potential adverse environmental problems will arise from small industrial plants, which will have to use coal, if the president's energy goals are to be met. Many small plants in the industrial sector use only a small quantity of fuel. Consequently, they normally have short stacks for discharging flue gases to the atmosphere. As a result, the pollutants are not diluted as are flue gases emitted from tall stacks, so that per unit of fuel consumed the ambient air quality is much more adversely affected.

The technology that is used for air pollution control at large utility or industrial boilers—electrostatic precipitators for particulates, and limestone scrubbing for sulfur oxides—will not be technically or economically usable at small installations. New research programs are needed to develop means to control particulates that do not require a trained mechanic to operate and maintain. Of even greater urgency is the need to find a method of controlling sulfur oxides that will not require the use of a scrubber. In addition, the disposal of the resulting sludge would be very difficult at small plants which are mainly located in or near urban areas. Government R&D programs directed toward these particular problems are needed urgently. Past efforts to encourage the industries which require control devices to voluntarily undertake major research efforts to develop improved control technology have not been very successful. Until methods are found that will give such industries incentives to conduct the research, a large part of the effort will continue to be borne by government.