The ETV Advanced Monitoring Systems Center, operated in cooperation with Battelle, has verified the performance of four mercury emission monitors for determining mercury in stack gas at a coal-fired power plant. In collaboration with the Illinois Clean Coal Institute, and with assistance from the Northern Indiana Public Service Co., ETV verified the following four monitors: Sorbent-Based Mercury Sampling System, developed by Apex Instruments Inc.; HG-324K System, developed by Environmental Supply Co.; Series 3300 Mercury Continuous Emissions Monitoring System, developed by Tekran Instruments Corp.; and Thermo Electron Mercury Freedom System, developed by Thermo Electron Corp.

The monitors were evaluated in terms of relative accuracy, linearity, seven-day calibration error, cycle time, data completeness and operational factors (ease of use, maintenance and data output needs, power and other consumables use, reliability, and operation costs). Under the Clean Air Mercury Rule issued by the EPA in 2005, most power plants are required to monitor their mercury emissions using such systems beginning Jan. 1, 2009. Verification reports and statements for these systems will be available soon on the ETV website at www.epa.gov/etv/verifications/vcenter1-11.html.