1. Sustainable Air Quality Michael Roberts February 4, 2002

2. Background Fossil fuels are consumed largely by industry. Sulfur and Nitrogen compounds are major fossil fuel pollutants. Elements such as carbon, sulfur, and nitrogen are redistributed by the industrial metabolism. These elements can be harmful if doses are high and for lengthy periods. In order to understand the benefits and/or effects of fossil fuels, a material flow diagram should be produced for the ecosystem analogue for humans. The process of this diagram starts with the mining process, then goes to the consumers and finally reaches the recyclers. Combustion of oil and coal products and the smelting of metals, are responsible for the majority of anthropogenic sulfur and nitrogen emissions. Since the 1880’s, fuel consumption has steadily increased.

3. Background Since 1850’s, the fuel source has changed throughout the years. Throughout history, fuel consumption has increased, but depending on the time period, a certain energy source may increase dramatically or decline dramatically.

4. Sulfur Production & Emissions After combustion, sulfur is transformed into SO2 & SO3. The environmental impact of sulfur begins at the mining process and continues to the atmosphere as sulfurous haze. There are three (3) main coal mining regions: the appalachians, the midwest (interior), and the west. Each region has a different amount of sulfur imbedded into the mined coal. For sulfur contaminant’s, we can figure out the sulfur contaminate by the equation Mi=CiPi where Pi is production rate and Ci is mass contaminate. Western coal has a significantly lower sulfur content than Midwest coal. Coal has been in use since about 1920. Even though coal production has increased significantly, the sulfur emission has only risen by 12%. Before 1945, coal was distributed among electric utilities, residential, railroad, and commercial. Today, coal is used mainly by electric utilities.

5. Sulfur Production & Emissions Sulfur mobilization from combustion oil products can be determined from production or consumption data. Sulfur mobilization increased untill about 1960 and then levels off at about 3-4 million tons per year. Methods have been used to reduce sulfur mobilization in crude oil. The by-product of recovering sulfur from crude oil is sulfuric acid. About 4 million tons of sulfuric acid is recovered yearly from crude oil. About 50-70% of sulfur oxides are removed from copper smelting. Since the turn of the century, sulfur emissions from metal smelting fluctuate between 0.5 & 1.5 million tons per year.

6. Nitrogen Oxides Emissions Nitrogen can be found in both the natural atmosphere and the biosphere. Transportation is responsible for almost half of all nitrous oxide emissions. The combustion temperature determines the NOx production. Nitrogen oxide is formed by fixation of atmosphere nitrogen at high temperatures of combustion rather than by oxidation of nitrogen in fuel. NOx emissions are calculated through the amount of fuel consumed and multiplying by an emission factor. Since 1970, NOx emission output has stayed relatively constant.

7. Summary National sulfur contaminates have fluctuated between 8 and 16 million tons per year. Since 1970, coal is responsible for the majority of sulfur oxides and nitrous oxides are a result of internal combustion engines. Today, coal is used primarily for boilers in the electric utility facilities. To control sulfur oxides, sulfur will have to be removed from the fuel and flue gases. To control nitrous oxide, technology will have to improve the combustion process.

8. What I learned Technology will have to reduce NOx. There isn’t much we can do. The Midwest mined coal is the highest sulfur content among the U.S. Even though coal production has increased, the sulfur pollutant hasn’t increased by the same amount that the production has increased by. The by-product of oil products is sulfuric acid.