T166 Coal Combustion Products and Impacts on the Society

Tuesday, 11 October 2011
8:00 AM - 12:00 PM
Room M100BC

LIFE CYCLE ANALYSIS OF USING COAL COMBUSTION PRODUCTS IN SUSTAINABLE CONSTRUCTION

Paper number: T166-10
Program: Technical Sessions
Time: 10:25 AM – 10:40 AM

Authors

Abstract

Use of coal as an energy source has increased over the last 30 years and coal will continue to be an important fuel for the foreseeable future. As a result of increased coal use and new air emissions controls, the production of coal combustion products (CCPs) is also increasing. Electric utilities produce around 130 million tons of CCPs annually. Approximately 50 million tons are used in a variety of applications. This study examined the environmental and cost benefits associated with the most common uses of CCPs in construction activities. Life cycle analysis programs were used to quantify benefits of using CCPs in sustainable construction. The analysis focused on the most common CCPs (fly ash, bottom ash, and flue gas desulphurization gypsum) and their most common applications (concrete production, wallboard manufacturing, and geotechnical applications) as identified through an analysis of industry CCP use data. Comparisons were made between energy consumption, water use, and greenhouse gas (GHG) emissions associated with conventional materials and procedures and those using CCPs. Cost savings were also quantified.

Beneficial use of CCPs reduced energy consumption by 63 trillion Btu, water consumption by 5.9 billion gallons and GHG emissions by 10 million tons CO2e. Cost savings ranged from $2.4-7.8 billion. The reduction in energy consumption is commensurate with energy consumed by 0.7 million homes (a large US city), the water saved is equal to 56% of the annual domestic water use in Arizona, and the reduction in GHG emissions is comparable to removing 1.8 million automobiles from the roadway.

The greatest benefits in sustainable construction are currently realized by using fly ash in concrete production. Use of fly ash as a cement substitute saved more than 55 trillion Btus of energy and reduced GHG emissions by 9.6 million tons CO2e. Using CCPs for geotechnical applications also resulted in significant energy savings (4.3 trillion Btu) and large reductions in water consumption (0.17 million gal) and GHG emissions (0.3 million tons CO2e). Smaller savings are achieved in energy consumption (0.3 trillion Btu) and GHG emissions (0.03 million tons CO2e) using FGD gypsum in wallboard production. Avoided CCP disposal resulted in savings of 3.7 trillion Btu of energy and a reduction of CO2e emissions by 0.3 million tons in 2007.