Sustainable Air Quality

Michael Roberts

February 4, 2002

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.

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.

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.

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.

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.

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.

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.