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Technological Alternatives to Reduce Acid Gas and Related Emissions from Energy-Sector Activities in Northeast Asia

David Von Hippel

November, 1996


Acid rain, caused primarily by emissions of nitrogen and sulfur oxides (NOx and SOx), is already having an environmental and economic impact in the countries of Northeast Asia. The problem is regional in scope, as emissions cross national boundaries and can have impacts in other nations. Projected growth in energy consumption in the region, particularly in the now-developing economies, creates the potential for vastly increased emissions in coming decades. This paper reviews a selection of options for reducing NOx and SOx emissions in five categories: post-combustion pollution control, burner modification, fuel pre-treatment, fuel-switching, and energy efficiency improvement. The relative cost per unit of emissions reduction of measures from each category are compared. A number of different options for regional cooperation to address SOx and NOx emissions reduction are suggested, as are particular opportunities for collaboration between the United States and Japan to assist countries of the region in reducing emissions.

Executive Summary

Of the many environmental concerns currently facing the nations of Northeast Asia, the problem of "acid rain" or "acid precipitation" presents perhaps the most potent combination of immediate and ongoing impact and regional scope. Acid rain in Asia has already been implicated in the declining health of some of the region's forests, in the premature weathering of metals and other man-made materials, and in the degradation of irreplaceable cultural monuments. Acid precipitation is primarily the result of the reaction of oxides of sulfur and nitrogen (SOx and NOx) the "acid gases"-with water or water vapor, yielding sulfuric and nitric acids. Acid gases can act as local air pollutants, or, depending on weather conditions and how they are emitted, can be transported for hundreds of kilometer or more. Acid gases are produced primarily when fuels are combusted, although smelting of the ores of some metals is also a significant source of sulfur oxides.

The recent and projected growth in economic output and fuels use in Northeast Asia creates both a challenge and an opportunity. The challenge is that unless changes are made in the way that fuels are used, acid rain and other environmental problems threaten to seriously erode (literally and figuratively) the gains of development. The projected increase in fuels use does, however, provide an opportunity for the countries of the region, in cooperation, to promote a development path for the developing nations of Northeast Asia that takes advantage of a suite of available measures, measures that not only reduce acid gas emissions, but can concurrently provide other environmental and economic benefits.

The types of measures available to reduce the quantities of acid gases emitted from the energy sector include:
Of these categories of measures, fuel-switching and energy-efficiency measures hold the most promise for reducing acid gases at costs that are either relatively low or negative (meaning that the measures pay for themselves with fuel, capital, and operating savings alone) on a net basis. End-of-pipe and burner modification measures are will continue to be important to retrofit the existing equipment in the region and to the extent that growth in coal-fired power will continue to occur. Burner modifications (such as "low-NOx" burners) in new combustion equipment typically add little to the cost of producing the equipment, and should be uniformly applied (as is increasingly the practice in industrialized countries). Coal cleaning will continue to be important to reduce the sulfur and ash content of lower-quality coals, to improve the combustion properties of coal, and to reduce coal transport costs. The reduction of sulfur contents of refined products is not a present widely applicable in China, which now uses mainly low-sulfur crude oil in its refineries, but probably will be in the future as China is forced to purchase more and more higher-sulfur crude oil from the Middle East.

How can regional cooperation help to implement some of these measures? Possibilities include: Some potential starting points for United States-Japan and regional collaboration in reducing acid gas emissions in Northeast Asia might include:
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