Transcript Monitoring and Controlling Mercury Emissions

Mercury Monitoring Approaches
for Small Units Under CAMR
Ruben Deza, PhD
Clean Air Markets Division
U.S. Environmental
Protection Agency
Introduction – Why Monitoring is
Important
 Monitoring and reporting of an affected source’s emissions are
integral parts of a cap and trade program, such as the one
described in the Clean Air Mercury Regulation (CAMR)
 Emissions monitoring establishes a “level playing field”, ensures
the integrity of the allowances, and instills confidence in the
trading program
 There is considerable variability in the type, size, operation and
fuel mix of sources affected by CAMR
Introduction – Why Monitoring is
Important (cont’d)

Emissions from the larger units must be monitored
continuously with rigorous quality assurance and quality
control requirements, to meet the emission reduction goals
and ensure the value of allowances and emission control
investments.

For smaller units, less rigorous monitoring and QA may be
appropriate
Mercury Monitoring Under CAMR
(The Basics)
 Required continuous monitoring for CAMR units:
 Hg concentration
 Stack gas flow rate
 Moisture---if needed
 Diluent gas (CO2 or O2)---if needed for heat input
 Monitor certification deadlines
 For existing units--- January 1, 2009
 For new units---90 operating days or 180 calendar days after
commencement of commercial operation
What Hg Monitoring Options are Available
Under CAMR ?
 Continuous Emissions Monitoring System (CEMS)


Similar to current CEM systems used in the Acid Rain & NOx budget
programs
Measures “real-time” vapor phase Hg concentration in the stack
 Sorbent Trap Monitoring System



Continuously samples the stack gas---collects vapor phase Hg on
sorbent media (e.g., activated carbon)
Hg accumulates in the sorbent traps over an extended period of time,
e.g., a few days or weeks
Lab analysis of the traps is required at the end of the data collection
period
 Alternative Monitoring System (via petition process under §75.66)
 Low Mass Emitter Option



Available only to units with very low annual Hg mass emissions
Requires the use of conservative Hg emission factors derived from
stack testing.
Also requires continuous monitoring of the stack gas flow rate.
Mercury CEMS -Status
 There are several Hg CEMS available in the market: Tekran,
Horiba/Nippon, Durag, Opsis, Thermo, Lumex, Forney/Genesis, and
GE/PSA
 Most manufacturers have made significant improvements to these
instruments in recent years, to correct problems identified in field
demonstrations.

While the reliability and accuracy of Hg CEMS continues to
improve, some technical issues still remain, e.g., probe
“survivability” on wet stacks, unexplained calibration error test
failures.
 CEMS are the preferred Hg monitoring option for large utility boilers
because of operational similarities to SO2, NOx and CO2 instruments
Mercury Sorbent Trap - Status
 Sorbent trap systems generally have performed well in field
demonstrations
 The capital investment required for these systems is smaller than for
CEMS but the operation and maintenance requirements are timeintensive.
 Remaining issues associated with sorbent trap systems include the
limited availability of sorbent materials and analytical laboratories,
and the length of time required for lab analysis of the traps
 Note that a new manufacturer of sorbent trap systems is now in the
market and will be participating in EPA’s field demonstrations
Mercury Monitoring at Smaller Units,
The Basics
 CAMR provides as much flexibility in Hg mass emission
monitoring as possible, while maintaining the high data quality
needed to run a market-based program
 CAMR requires Hg mass emissions monitoring in accordance
with Subpart I of 40 CFR Part 75
 Any affected unit may use an Hg CEMS or a sorbent trap
system.
 Consistent with the SO2 and NOx cap-and-trade programs,
sources may also petition to use an alternative monitoring
system (AMS), under Subpart E of Part 75


For an AMS, other monitoring approaches or variations may be
proposed to meet the performance requirements in Part 75.
However, the requirements for an AMS are very rigorous. The AMS
must provide data of the same precision, reliability, accessibility, and
timeliness as a CEMS.
Mercury Monitoring at Smaller Units,
The Basics-(cont’d)
 A less rigorous monitoring approach (§75.81(b)) may be used
for low emitting units—may be a good option for smaller units
 For a unit to qualify as a low emitter, the owner/operator must
perform Hg emission testing to demonstrate that the unit’s
potential to emit is < 29 lbs/yr of Hg.

If the unit qualifies, a default Hg concentration is used for reporting,
i.e., the greater of: the highest concentration from the testing or
0.50 µg/m3

Periodic retesting is required, using a two-tiered approach


Semiannual testing if potential to emit is > 9 lb/yr but < 29 lb/yr
Annual testing if potential to emit is < 9 lb/yr
Cumulative HG Emission Distribution Based on 1999 Hg ICR
(1120 Total Sources)
120000
Note: Total of Cumulative Emissions: 95,975 lbs
20% Hg Emissions
Unit Cutoff: 76 lbs/yr
724 Units
Cumulative Hg Emissions (lb)
100000
10% Hg Emissions
Unit Cutoff: 46 lbs/yr
565 Units
80000
5% Hg Emissions
Unit Cutoff: 29 lbs/yr
435 Units
60000
1% Hg Emissions
Unit Cutoff: 9 lbs/yr
228 Units
40000
20000
0
1
101
201
301
401
501
601
Number of Units
701
801
901
1001
1101
Other Issues
 Demonstrations
 IRM
 NIST
 Rulemaking changes
 Additional rule info