Coal-fired power plants variability

Variability of Compositions of Particles Released by Coal-Fired Power Plants... 

Particulate emissions data for 21 studies of coal-fired power plants were compiled for use in receptor models. Enrichment factors were calculated (relative to Al) with respect to the earth s crust (EFcrust) and to the input coal (EFcoai). Enrichment factors for input coals relative to crustal material were also calculated. Enrichment factors for some elements that are most useful as tracers of coal emissions (e.g., As, Se) vary by more than ten-fold. The variability can be reduced by considering only the types of plants used in a given area, e.g., plants with electrostatic precipitators (ESPs) burning bituminous coal. For many elements (e.g., S, Se, As, V), EFcrust values are higher for plants with scrubbers than for plants with ESPs. For most lithophiles, EFcrust values are similar for the coarse (>2.5 ym) and fine (<2.5 ym) particle fractions. 

In this paper we have focused on the two largest shale gas resources in the U.S. Many other U.S. shale plays have intermediate characteristics and variability. Therefore, we conclude that substantial GHG reductions and water consumption may result by replacing coal-fired power plants with... 

F, Hg, Mo, Ni, Pb, S, Sb, Se, and Zn. The comparison of partitioning data previously developed for bituminous and subbitum-inous coals with samples of lignite, bottom ash, and fly ash from two Texas lignite-fired power plants showed great variability in results. Therefore few conclusions regarding trace element partitioning as a function of coal rank can be drawn at this time,... 

Ash is the noncombustible residue remaining after the burning of any substance. Although quite variable in physical form and chemical composition, ash is typically composed of silicates, oxides, carbon, sulfur, and metals. Workers may be exposed to ash from coal and oil-fired power plants, ash from ineinerators, ash from wood and other plant materials, and volcanic ash. A significant portion of most airborne ash is in the respirable size range. Fisher et al. (58) and Hatch et al. (59) described coal and oil fly ash, Fruchter et al. (60) described volcanic ash from the 1980 Mount St. Helens eruption in the United States, and Alarie et al. (61) described ash from munieipal incinerators. 

Based on the above description of the coal combustion process several conclusions become apparent. First, the type and amount of ash accumulated during coal combustion greatly depends on the mineralogy of the coal being used, the combustion process, and the presence of emission control devices. Secondly, the chemical forms in which elements are found in ash are affected by coal combustion process variables such as combustion temperature and the mode of combustion (e.g., pulverized-coal fired, fluidized bed, cyclone, stoker). Lastly, the amount of CCPs accumulated by power plants is predominantly a consequence of the presence of emission control devices. The latter is supported by the fact that the total amount of CCPs produced in the US has increased significantly since the use of electrostatic precipitators became prevalent in the early 1970s (Simsiman et al. 1987). 

These examples show clearly that any grid that includes NPPs and/or renewable energy sources must also include fast-response power plants such as gas- and coal-fired and/or large hydro power plants. This is due not only to diurnal and seasonal peaking of demand but also the diurnal and seasonal variability of supply. Thus, for any given market, the generating mix and the demand cycles must be matched 24 h a day, 7 days a week, 365 days per year, independent of what sources are used, and this requires flexible control and an appropriate mix of base-load and peaking plants. 

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