POWER July 2016 - 27

ENVIRONMENTAL ISSUES
Simplify MATS Compliance with
Particulate Matter Continuous
Emission Monitors
Courtesy: Gail Reitenbach
Now that power plant operators have some experience under their belts related
to Mercury and Air Toxics Standards (MATS) compliance, it's time to reevaluate
the options for demonstrating compliance.
Rick J. Krenzke
S
tarting with the Clean Air Act of 1970
and its updates, compliance for utility
and industry stationary sources has
only increased in complexity. The Environmental
Protection Agency (EPA) has targeted
many industries that emit criteria pollutants
and hazardous air pollutants (HAPs) and has
written regulations to ensure that affected
industries control the release of pollutants
by implementing the most effective control
technologies.
Most recently, the Mercury and Air Toxics
Standards, known as MATS, has been added
to the list of regulations. MATS establishes
emission limits for three HAP categories:
mercury, non-mercury metals, and acid gases.
Importantly, particulate matter (PM) is a
surrogate for non-mercury metals.
This article focuses on the EPA's requirement
for Maximum Achievable Control
Technology (MACT) as it applies to electric
generating units (EGUs). An EGU must demonstrate
compliance with the MATS limits,
and MATS offers options for demonstrating
compliance. An EGU can use continuous
emission monitoring systems (CEMS) or a
combination of CEMS and periodic testing
using conventional reference methods. By
understanding these options, source owners
can implement strategies that allow facilities
to set their source-specific operating limit
July 2016 | POWER
closer to their PM compliance limit, which
will help limit the risk of noncompliance.
MATS was promulgated in February 2012
and the industry had three years to demonstrate
compliance (with a possible one-year
extension in some cases). Coal- and oilfired
source operators had to analyze the
regulations and define a strategy for mercury,
non-mercury HAP metals, and acid gases
compliance, based on the type of existing
equipment they operated and the potential for
add-on abatement equipment.
When considering non-mercury metal
HAPs, the choice of PM as a surrogate simplified
the strategy for many sources. Given
that many PM monitor vendors were developing
monitors to comply with this new regulation
and historic data using PM monitors
for compliance demonstration purposes in
the U.S. was limited, many source owners
defaulted to the quarterly PM stack testing
option until PM monitor data, history, and
resources could be researched.
Now, four years into the MATS compliance
era, enough historic data and improved monitors
exist to potentially change the PM compliance
strategy to one that uses a PM monitor
instead of quarterly PM stack testing.
CEMS vs. CPMS
To comply with the non-mercury HAP metwww.powermag.com
als
limits, an EGU can conduct quarterly
manual reference method testing for metals
or manual reference method testing for PM,
the surrogate for non-mercury metal HAPs.
Alternately, if the EGU chooses to use PM
as a surrogate, it can install a continuous PM
monitor and operate it as either a CEMS or
a continuous parametric monitoring system
(CPMS).
If the PM monitor is operated as CEMS,
a correlation curve must be generated by
statistically comparing CEMS data to reference
method data as set forth in Performance
Specification 11. If the PM monitor is operated
as a CPMS, reference method PM testing
is used to demonstrate compliance with
the MATS PM limits at normal operation.
The response of the PM monitor that corresponds
to this reference method PM testing
is recorded and is considered to be the
source-specific operating limit. As long as
the 30-day rolling average output of the PM
monitor stays below the source-specific operating
limit, the source is considered in compliance
with MATS for non-mercury metal
HAPs using PM as a surrogate.
The Changing Role of Pollutant
Monitors
Pollutant monitors play a critical role in
demonstrating continuous compliance.
27
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POWER July 2016

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