Coal for power generation

As a result of the Brown Coal Evaluation Program, the understanding of the variability of Victorian brown coals and its implications for utilization have improved substantially. It has become apparent that certain chemical properties can have important consequences for utilization of the coal for power generation, liquefaction and other applications. 

Environmental Protection Agency (EPA) recently stated that about half of the new state standards limit the sulfur content of coal to less than 0.8%, even though it noted at the same time that not enough low sulfur coal supply is projected to meet these requirements. Accordingly, there will be limited supplies of low sulfur coal for power generation and other purposes unless it is determined that environmental standards need not be as stringent in some areas as initially considered. 

Treatment of many materials results in the liberation of the trace elements into the environment, which can have an impact on health. Coal is a particularly useful example of a major source of trace elements poured into the environment from coal combustion. Coal contains an alphabet soup of trace elements, including arsenic, mercury, uranium, selenium, and chromium. Pyrite is a ubiquitous mineral found in coal, but coal can also contain a variety of other mineral phases. West Virginia coal, for example, includes clay minerals such as kaolinite (35%) and illite (35%i), quartz (18%i), pyrite (7%), and calcite (3%). A number of projects that utilize coal for power generation while minimizing the impact on the environment have been described. An excellent example is the SNOX (trademark owner Haldor Topsoe) demonstration project, which utilizes high-sulfur coal (2.8%). The demonstration project of this technology, equally funded by the U.S. Department of Energy and participants at a total cost... 

In addition, for the more conventional uses of coal for power generation and production of coal tar and coke (Part 11), a number of processes have been developed by which solid coal can be converted to a liquid or gaseous form for use as a fuel. Conversion has a number of advantages. In a liquid or gaseous form, the fuel may be easier to transport. Also, the conversion process removes a number of impurities from the original coal (such as sulfur) that have environmental disadvantages. 

The use of coal as a fuel and the varied, often detrimental, effects of the mineral matter on the fuel properties of coal has been a source of concern for consumers (Alpern et al., 1984). Even the interactions of the mineral constituents themselves (Table 7.9) have directed interest toward the mineral constituents of coals but with the tendency to an increased use of coal for power generation as well as for gasification and conversion plants that will enable coal to act as a source of liquid and gaseous fuels. Therefore, methods by which the mineral matter can be evaluated have been a constant target for quantitative and qualitative improvement. 

Yegulalp TM, Lackner KS, Ziock HI (2001) A review of emergiug technologies for sustainable use of coal for power generation. Int J Surf Mining Reclamation Environ 15 52-68. doi 10.1076/ijsm.l5.1.52.3423... 

Iyengar, R. and Haque, R. (1991) Gasification of high-ash Indian coals for power generation. Fuel Processing Technology, 27 (3), 2A7-262. 

Other Regions. In AustraUa, Victoria has the largest reserves, although smaller ones occur in southern AustraUa, western AustraUa, Tasmania, and Queensland (28). The main deposit consists of many thick seams in about 500 km of the Latrobe Valley. The YaHourn coal field provides most of the fuel. The top coal seam is 65 m thick and is covered with 13 m of overburden. Most of this coal is used for electric power generation. It is very moist (55—72%), but has less than 5% ash. The lignitic coal found in South AustraUa is, for the most part, too deep for economic recovery. However, some of the better deposits are mined for power generation. 

G. W. Roberts, N. K. Dicciani, J. Klosek, Conference on Coal Gasification and Synthetic Fuels for Power Generator, San Francisco, Calif., Apr. 14—18,1985. 

If all these process and economic advantages are reahzed, the cost of electricity l be lowered, making circulating PFBC an extremely attractive coal-fired option for power generation. 

The use of coal for electricity generation is responsible for about 32% of anthropogenic carbon dioxide emissions in the U S. 11 As shown by France, it is possible to displace virtually all the coal used in electricity generation. Thus, France in 1997 obtained about 78% of its electricity from nuclear power and only about 5% from coal. Further reductions in carbon dioxide emissions could be made by the electrification of other sectors of the energy economy, including buildings, and eventually perhaps much of transportation. 

CAFB [Chemically active fluidized-bed] A coal-gasification process intended for producing gas for power generation. Coal particles are injected into a shallow bed of lime particles that trap the sulfur dioxide. The bed particles are regenerated in a second fluidized bed, releasing the sulfur dioxide. Developed in the 1970s by the Esso Petroleum Company, UK, but not commercialized. 

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