Coal-fired power plants atmospheric emissions

Figure 12 shows the quantity of CO2 emitted into the atmosphere from two geothermal power plants in Iceland and how it compares with CO2 emission from fossil fuel plants. At Krafla, the quantity of C02 emitted per MW-year (MWy) is 8401, which is only about 10% of that from a typical coal-fired power plant (8760 t/MWy, Armannsson Kristmannsdottir 1992). The... 

Kowalczyk, G. S., "Emission and Atmospheric Impact of Trace Elements from a Reconverted Coal-Fired Power Plant," Preprint for 77th Annual Meeting of the Air Pollution Control Association, San Francisco, CA, June 24-29, 1984. 

Our goal is to gradually replace all coal and fossil fuel power plants with renewable energy ones, but while they exist (and probably will for most of this century), it is very important to reduce the damage they cause by optimizing their operation. In the United States, there are about 1000 coal preparation plants and coal-fired power plants. One key consideration in operating coalburning facilities is the control of C02 and sulfur dioxide (S02) emissions to the atmosphere. The characteristics of coal are monitored for environmental protection, quality assurance, and process control purposes. 

The phosphor production plant located near the power station of Borssele, produces phosphor oven gas (mainly consisting of CO and H2, which was partially used on this industrial site and partly flared. By creating the possibility of co-combustion in the coal-fired power plant a reduction in atmospheric emissions of CO2, SO2 and NOx was obtained for this industrial region. The gas cannot be stored and must therefore be used at the power station the moment it cannot be applied at the phosphor production plant. In practice, this means that co-combustion mainly takes place during nighttime, when the unit is operated at half load. A concern at the start of the project was whether the quality of the fly ash for concrete production could be influenced by substantial amounts of phosphate. The residual amounts of phosphor in the delivered gas however, turned out to be so low that no adverse effects were observed. 

The concept, presented in the paper, forecasts a big profit when using new coal-fired power plants without any atmospheric emissions and injection of high pressure carbon dioxide, produced in the plant, into old oil fields for almost total oil extraction. With a capacity of 14 GW in Europe it is possible to extract 300 Mt of oil. The concept is undoubtedly worth being funded for further studies for the design of a demonstration plant. 

Norway, with a tax as high as 54.00/t of C02, is currently gaining attention for its massive sequestration project, the sole purpose of which is to avoid atmospheric emissions. At the Sleipner Field, Statoil of Norway separates C02 associated with natural gas production from even deeper geological strata at the same site. Statoil annually injects one million metric tons of C02 into a capped geological formation 1000 meters below a shallow sea inlet. To provide a basis for comparison, this is approximately the C02 output from a 120-MW electric coal-fired power plant. 

If this development continues, there is little doubt that more regional problems will appear. Incidents of "red tide" are reported from the North Sea area. This is an over-growth of toxic algae which follows excessive deposition of nitrates by precipitation and kills the fish. Watersoluble mercury compounds in the atmosphere, partly due to emissions from coal-fired power plants and partly due to an oxidation of the natural mercury vapour, have resulted in a serious contamination of freshwater fish in Scandinavia. Already fish from many lakes cannot be marketed in Sweden, because the mercury content exceeds 1 mg/kg. 

Antimony oxides are released into the environment from smelters, coal-fired power plants and volcanoes (Zoller 1984). Lantzy and Mackenzie (1979) estimated that 3.8x 10 g per year were released globally into the environment from anthropogenic activities. Another important source is vehicle emissions (Dietl etal. 1996). Antimony is transported in the atmosphere over long distances - for instance, from Central Europe to Norway - and accumulates there in soils, plants, mosses, etc. (Steinnes 1997). About 4 tons of antimony are deposited on the Arctic from northern Europe annually... 

Mercury emission from electric utilities is the largest uncontrolled source of mercury release into the atmosphere, and globally it accounts for up to 59% of the total annual atmospheric loading of mercury from both natural and anthropogenic sources. Coal-fired power plants are now considered the greatest source of environmental mercury in the U.S., and the only significant source that continues... 

Sulfur and nitrogen oxides are not the only output from coal combustion that may leave a detectible environmental impact. Particulate matter (fly ash) is also released during coal combustion and can be detected near coal-fired power plants (Flanders, 1999 Godbeer and Swain, 1995 Kapicka et al, 1999). The focus of the present study was to test whether these particulate emissions have produced a detectible impact on the geochemical landscape downwind from power plants. It is already known that atmospheric inputs can be detected in lake and reservoir sediments (Locke and Bertine, 1986 Norton, 1986), and we sought to further test whether atmospheric coal fly ash inputs could be identified and quantified. 

The sulfur gas produced by burning coal can be partially removed with scrubbers or filters. In conventional coal plants, the most common form of sulfur dioxide control is through the use of scrubbers. To remove the SO2, the exhaust from a coal-fired power plant is passed through a mixture of lime or limestone and water, which absorbs the SO2 before the exhaust gas is released through the smokestack. Scrubbers can reduce sulfur emissions by up to 90%, but smaller particulates are less likely to be absorbed by the limestone and can pass out the smokestack into the atmosphere. In addition, scrubbers require more energy to operate, thus increasing the amount of coal that must be burned to power their operation. 

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