Coal utilization, environmental concerns

Beyond the ATS program, the DOE is looking at several new initiatives to work on -with industry. One, Vision 21, aims to virtually eliminate environmental concerns associated with coal and fossil systems while achieving 60 percent efficiency for coal-based plants, 75 percent efficiency for gas-based plants, and 85 percent for coproduction facilities. Two additional fossil cycles have been proposed that can achieve 60 percent efficiency. One incorporates a gasifier and solid oxide fuel into a combined cycle the other adds a pyrolyzer with a pressurized fluidized bed combustor. Also under consideration is the development of a flexible midsize gas turbine. This initiative would reduce the gap between the utility-size turbines and industrial turbines that occurred during the DOE ATS program. 

The disposal of coal combustion residues must take into account the nature and amount of the products to be disposed, as well as the nature of the disposal environment. It is a characteristic of coal utilization that many historic wastes exist that lack, or almost totally lack, characterization data. Only in recent decades, with concern over the environmental impacts of present and future accumulation of wastes, have characterization studies been made. The principal types of waste are described in Table 5. 

Fynes G British Coal Corporation Coal Research Establishment Stoke Orchard, Cheltenham, England Emissions of Environmental Concern from Coal Utilization European Coal and Steel Community (ECSC) British Coal Corporation Department of Trade and Industry... 

Trace Elements of Environmental Concern. In a list prepared by a panel o scientists and engineers involved with environmental aspects of coal utilization, As, B, Cd, Hg, Mo, Pb, and Se were considered to be of primary environmental concern (8j. The elements Cr, Cu, Ni, V, and Zn were of moderate concern, while Ba, Co, Ge, and toi were believed to be of minor concern. Despite the toxicity of Ag, Be, Sn, and Tl, the panel believed concentrations of these elements in coal and coal residues are negligible and that the likelihood of health hazards associated with these constituents is remote. This list served as a guide in choosing the elements to be determined in raw and treated coals in this study. However, some of the elements, such as B, were not studied in this work due to the inherent difficulties with the analytical procedures and instrumental methods employed. 

More efficient coal utilization can be realized with combined power plant cycles. For instance, the post combustion gases of a conventional combustor or an advanced MHD system can be further utilized to drive a gas or steam turbine. However, the sustained durability of downstream turbine or heat exchanger components requires minimal transport of corrosive fuel impurities. Control of mineral-derived impurities is also required for environmental protection. For the special case of open cycle-coal fired MHD systems, the thermodynamic activity of potassium is much higher in the seeded combustion gas (plasma) than in common coal minerals and slags. This results in the loss of plasma seed by slag absorption and is of critical concern to the economic feasibility of MHD. 

Besides, Nanzhuang Coal Mine stored the drained methane and then utilized these gases for economic and environmental concerns, and these will be presented in the next section. 

Concerns about the environmental effects of emissions resulting from the combustion of fossil fuels, particularly coal, continue to increase as the utilization of these fuels grows. The large amounts of sulfur dioxide and nitrogen oxides emitted into the atmosphere and the attempts to tie these fossil-fuel-derived pollutants directly to the undeniably difficult problem of acid rain have caused heated debates, numerous research studies, government actions, and serious efforts to reduce pollution. The issues are extremely complex, and our understanding of the origin, properties, behavior, and effects of these pollutants is incomplete. Often, theories are contradictory. 

Concern for supplies of low sulfur coals, and other coals which can meet environmental requirements through chemical processing and other technologies, is compounded by enormously increasing needs for energy fuels by electric utilities, the extent to which low sulfur coals are held and used for coke production for steelmaking (both at home and abroad), and the relative availabilities of the other energy sources. 

Coal mine gas (called Coal bed Gas) is a kind of associated gas from the coal seam in coal mine exploitation process in different forms, which is one of the main reasons of the coal mine accident. As the first fatal factor in coal mine, the gas accident not only causes a large number of casualties and huge economic losses, and imperils the safety of coal mine production seriously once it occurs. Gas concerns the major issues of environmental pollution, the greenhouse effect and the future of new energy. It can be used after recovered rapidly if the coal mine gas develops, storages and transports high-efficiently in moderate environment. Meanwhile it will be reduced that the cost, the hidden safety trouble and the gas emission pollution to the environment. Thus it is badly in need of a new type of gas utilization technology to make up for the current technical defects. Hydrate method is an optional way. 

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