Sustainable Air Quality

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.