Status of Alternative Reference Methods for Mercury Emission Measurements – Part 1 Scott Hedges, USEPA, CAMD EPRI CEM Users Group Meeting Phoenix, AZ May , 2007

Need for Alternative Reference Methods uReference methods will significantly help in performing RATAs of the mercury CEMS and sorbent trap monitoring systems required by CAMR uThe currently-available reference method – Ontario Hydro – uses wet chemistry techniques and typically requires 2-3 weeks of laboratory analysis before the test results are known uThe alternative reference methods should allow for RATA results to be known while the test team is on-site. uAs such, timely alternatives to the lengthy and complex Ontario Hydro reference method are strongly desired uIn fact, these alternative reference methods are needed as soon as possible –Most Hg CEMS and sorbent trap monitoring systems will need RATAs in 2008 to meet 1/1/2009 deadline –Many utilities are also planning RATAs this year

Evaluation and Validation of Alternative Reference Methods u EPA and industry (EPRI and others) are completing remaining field validation tests for the instrumental and sorbent trap-based reference methods u An instrumental reference method (IRM) that provides timely RATAs with immediate, real-time results is easier to implement than OH and is consistent with NO X and SO 2 trading programs u A sorbent trap reference method is considered another viable alternative method. When it combines thermal desorption / direct combustion techniques, it allows for onsite analysis u EPA and EPRI are currently completing sorbent trap method comparison studies using a modified EPA Method 301 which compares existing data from sorbent trap systems against data from the Ontario Hydro reference method. –Body of sorbent trap data has been favorable (i.e., good agreement with Ontario Hydro)

Availability of Alternative Reference Methods EPA is preparing a rule package for both the instrumental and sorbent-based reference methods -Process being expedited through direct final rule making effort -Final rule tentatively scheduled for early August publication in the Federal Register -Would become final in October if no adverse comments are received -Methods will be made available at

Mercury Instrumental Reference Method (IRM) uTimely (real-time) uPerformance-based –Amenable to multiple and new technologies –Test program-specific verification of data quality –Agency committed to performance-based methods (Federal Register Notice of Intent 62 FR 52098, 10/6/97) uConsistent w/ SOx & NOx instrumental methods uKey elements –Calibration error/linearity –System integrity/conversion efficiency –System response time –Interference test –Dynamic spiking (gaseous method of standard additions)

Mercury IRM Development u Used Methods 6C (SO 2 ) and 7E (NO x ) as starting point and factored in lessons learned from Hg CEMS demonstrations u Drafted Conceptual IRM and posted 2/28/06 at: u Evaluated in field by EPA/ORD, EPRI, and others

Planned Modifications to 2/28/06 Version of IRM u Requiring only pre-test dynamic spiking and making optional until 1/1/09 u Relaxing Hg 0 calibration error criteria u Simplifying Hg 2+ calibration to a system integrity check u Relaxing drift criteria u Making interference test optional u Waiving Hg stratification testing until 1/1/09 and adding a “low emitter cutoff”

Sorbent Trap Reference Method for Mercury uPerformance-based –Amenable to new sorbents, equipment, and analytical technologies »Lab verification of sorbent performance and analysis »Test program-specific verification of data quality uCapability for timely results uDescription –Known volume of stack gas is sampled through paired, in-stack 2-section sorbent traps (e.g., iodated carbon) –Analysis by any suitable system that can meet performance criteria (e.g., leaching, digestion, thermal desorption/direct combustion coupled with UV AF, UV AA, XRF)

Sorbent Trap Reference Method for Mercury, cont. uKey QA Elements –Laboratory »Matrix interference test (for wet digestion analyses) »Minimum sample mass determination »Analytical bias test (Hg 0 and Hg 2+ ) –Field (for each test) »Paired train agreement (assess precision) »Sorbent trap second section breakthrough »Field recovery test (assess bias)

Questions? Comments? THANK YOU!