Fuels combustion, environmental impacts

Over the past decades, advances have been made that reduce environmental impacts of coal burning in large plants. Some arc standard and others experimental. Limestone (mainly calcium carbonate) scrubber smokestacks react with the emitted sulfates from the combustion and contain the chemical products, thereby reducing the release of SO., into the atmosphere by a large factor (of ten or more). Pulverization of coal can also allow for the mechanical separation of some sulfur impurities, notably those in the form of pyrites, prior to combustion. Currently deployed—with more advanced versions in the development stage—are various t yies of fluidized bed reactors, which use coal fuel in a pulverized form, mixed with pulverized limestone or dolomite in a high temperature furnace. This technique reduces sulfate release considerably. There are... 

Coal is one of the major fuels in Ukraine where its environmental impact is much higher than that of nuclear energy, provided that there are no accidents. Yet there is no alternative to coal, for natural gas can only cover the most urgent household and industrial needs, not to mention the country s indebtedness for its imports. The question of environment-friendly combustion of coal is therefore highly topical. 

Desulphurisation of hydrocarbon fuels has traditionally been carried out primarily as part of the refining and upgrading process. Accordingly by far the most advanced and best understood chemistry and technology is to be found in this area. Prior to the advent of major concern for environmental impact of fossil fuel combustion products relatively little was done to desulphurise hydrocarbon fuels (principally coal) prior to combustion and past effects of large scale consumption of high sulphur coals can still be seen in major industrialised areas around the world. 

The recovered sulfur industry exists primarily as a result of the necessity of removing sulfur values from hydrocarbon fuels before combustion so that sulfur emissions to atmosphere are reduced. In the case of sour gas, the principal source of recovered sulfur, the product that results from recovery of the sulfur is clean-burning, non-polluting methane. In the case of refineries handling high sulfur crude the product is low sulfur gasoline and oils. Thus every ton of sulfur recovered is a ton that is not added to the atmosphere. The recovery process itself however, is also the subject of optimization and recent developments in recovery efficiency have further ensured that the environmental impact in the immediate vicinity of these desulfurization facilities will be minimized. 

In the previous chapters, thermodynamic analysis is used to improve processes. However, as pointed out in Chapter 9 (Energy Conversion), the exergy analysis did not make any distinction between the combustion of coal and natural gas and, as a result, could not make any statements regarding toxicity or environmental impact of exploration, production and use of the two fuels. A technique that can do this is LCA. What exactly is life cycle analysis In ISO 14040 [1], life cycle analysis (or life cycle assessment) is defined as "the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product throughout its life cycle."... 

A similar opportunity exists for the public utility industry in the potential of LBG and MBG. The reduced environmental impact of a coal gasification plant which produces a perfectly clean fuel equivalent to natural gas, compared to direct combustion of coal may allow increased use of coal in areas where increased pollutant emission is barred. As these PSD areas increase in number, the advantages of coal gasification become more apparent. The potential of more efficient combined cycle generation systems which can be used with coal-derived gases is an added factor for implementing coal gasification. 

Someday we will run out of fossil fuels and perhaps more importantly, someday the environmental impact of these fuels will catch up with us. Global warming is a real threat, but fossil fuel combustion [burning] also causes local pollution. We need to stop burning things as much as possible ... 

As there is no politically and economically attractive alternative to energy generation by fossil fuels during the next several decades, research is being conducted to reduce the environmental impact of fossil fuel burning by reducing or sequestering the CO2 produced by fossil fuel combustion. 

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