Optimizing Technology to Reduce Mercury and Acid Gas Emissions from Electric Power Plants: A GIS Study of Coal Chemistry

Sponsoring Organization: Utah Geological Survey
Point of Contact: Roger Bon (rogerbon@utah.gov)

Background
In December 2000, the U.S. EPA determined that regulation of mercury emissions from coal-fired electric power plants is appropriate and necessary to protect the public health. The EPA regulations will be proposed by December 2003, finalized by December 2004, and enforced by January 2008.

Objective
We will investigate how the geographic variation of coal chemistry relates to mercury and acid gas emissions from conventional coal-fired electric power plants.

Rationale
Despite proven emission control technology, burning low-sulfur coal is the most popular method to reduce sulfur emissions. Because technology to reduce mercury emissions is considerably less certain, burning low-mercury coal is a likely method to reduce mercury emissions. Like sulfur, the amount of mercury in U.S. coal shows substantial geographic variation. Furthermore, mercury emissions from similar types of power plants are largely correlated with the amount of mercury in the coal.

However, unlike sulfur, mercury emissions also vary with the abundance of other elements in the coal such as chlorine and sulfur, which influence the amount of mercury removed by emission control technologies. Consequently, mercury emission factors vary according to the relative abundance of several elements in the coal and are specific to different emission control technologies.

Approach
This 24-month project will create 10 or more detailed maps of the contiguous U.S. to show where coals with low mercury and acid-gas emissions might be found. We will use recently published coal quality data (~ 75,000 data records) and Geographic Information System technology (ArcView GIS) to create a series of maps that show the geographic variation of mercury and acid-gas precursors (sulfur, chlorine, fluorine) in coal.

The series will also include maps showing mercury emission factors calculated for groups of power plants classified by boiler type and flue gas emission controls. Although each map will cover the entire lower 48 states, the data will be aggregated by county-of-origin to show local variation of coal chemistry within different coal-producing regions. To make the results accessible to industry, presentations will be made at industry meetings and both the raw data and the derived maps will be posted on a project web site.

Removing mercury from flue gas is a technically complex task – different technologies will be required for different coals. Maps showing the geographic variation of mercury and acid gas emission factors for U.S. coals will locate the best coals for each technology and may help to identify the best technologies for each coal.