Traditional PM Emission Factors Being Left in the Dust

Traditional PM Emission Factors
Being Left in the Dust
(ENV-13-10)
Presented by:
Louis Corio & Karen Olson
Zephyr Environmental Corporation
Presented at:
2013 AFPM Environmental Conference
October 21, 2013
Presentation Outline
• Introduction
– Scope of presentation
– Why traditional particulate matter (PM) emission factors need
to be left behind
– Quality of available factors
• PM measurement methods background
• What do we do now?
• Alternate PM emission factors
– Research studies: NYSERDA/API
– Examples of recent approved use of alternate factors
• Summary and concluding remarks
Introduction: Scope of Presentation
• PM emissions from natural gas- and refinery fuel
gas-fired combustion units: boilers, heaters, and
combustion turbines
• PM references include TSP, PM10, and PM2.5
Introduction (cont’d): Why do Traditional
PM Emission Factors Need to be Left Behind?
• Relatively new PM2.5 requirements necessitate a
more rigorous approach to obtain a representative
PM emission estimate
• Air permit applicants:
– Compliance demonstration for restrictive PM2.5 NAAQS
– 10 tpy PM2.5 significant emission rate for PSD and NNSR
applicability
• State and other regulatory agencies need
representative PM2.5 emission inventories for SIP
planning
Introduction (cont’d): Why do Traditional
PM Emission Factors Need to be Left Behind?
• Historically, PM emission rates for gas-fired
combustion units have been estimated base on:
– AP-42 emission factors, which are not considered good
factors even by EPA, or
– Vendors’ PM emissions guarantees, which in most
cases yields a total PM emission factor similar to the
AP-42 factor because of test data methods and desire
to minimize risk
• Based on the above, PM emissions have been
significantly overestimated historically
Introduction: Quality of AP-42
Emission Factors
• EPA AP-42 ratings of emission factors based on
– Quality of data relied upon for factor development
• Is the methodology sound?
• Amount of data with supporting test detail?
– Is the data representative of the variability expected in
the source type?
• EPA AP-42 emission factor ratings:
A - Excellent
B - Above average
C - Average
D - Below average
E - Poor
Introduction (cont’d): Quality of AP-42
Emission Factors
• Boilers/heaters:
– Filterable PM – “B” rating
– Condensable PM – “D” rating
– Condensable PM factor based on
four tests conducted earlier than
the mid-1990s
• Turbines:
– Filterable PM – “C” rating
– Condensable PM – “C” rating
– Filterable and condensable PM factors based on three
tests conducted at one facility in the mid-1990s
Presentation Outline
• Introduction
– Scope of presentation
– Why traditional PM emission factors need to be left behind
– Quality of available factors
 PM measurement methods background
 What do we do now?
 Alternate PM emission factors
– Research studies: NYSERDA/API
– Examples of recent approved use of alternate factors
 Summary and concluding remarks
PM Measurement Methods Background
• Total PM = Filterable PM + Condensable PM
• For gas-fired combustion units, condensable PM is
the dominant component
• Condensable PM is comprised of inorganic and
organic matter fractions; on average, for gas-fired
units, the inorganic fraction predominates
• All condensable PM is in the PM2.5 size fraction
PM Measurement Methods Background
(cont’d)
• EPA’s test methods (TMs) for PM:
– TSP: TM 5 (filterable PM), originally established in 1971
– PM10:
• TM 201/201A (filterable PM), originally established in 1990,
and
• TM 202 (condensable PM), originally established in 1991
• EPA revised TMs 201A and 202 in December 2010
• TMs 201A and 202 were revised to provide more accurate
condensable PM measurement and PM2.5 speciation
PM Measurement Methods Background
(cont’d)
• For gas-fired units, very low levels of PM mass is in
the exhaust, therefore:
– TM established sampling time (one-hour test runs)
results in very small sample mass collected
– Any amount of error introduced during sampling or
analysis could result in significant high bias and
unrepresentatively high PM emissions from test results
PM Measurement Methods Background
(cont’d)
• Therefore, despite EPA’s TM revisions, a significant
amount of potential measurement uncertainty is likely to
result from technique and implementation of the TM,
such as:
– Contamination of sampling train equipment and/or
laboratory apparatus and/or reagent
– Contamination during sample handling
– Errors in analytical procedures (e.g., filter
measurement error)
– PM artifact formation
– Elevated background PM concentration
PM Measurement Methods Background
(cont’d)
• The potential error introduced with sampling and
analytical method implementation must be addressed
before, during, and after the stack test to minimize any
potential bias in emissions
• Historically, until the last few years, these implementation
issues in routine PM stack testing have not received a lot
of attention
• Therefore, the emission factors based on historical test
results are not likely to be representative
What Do We Do Now?
• Summary of the Issue: The use of AP-42 emission factors and or
equivalent vendor guarantees can be expected to over-estimate PM
emissions, especially for condensable PM:
– AP-42 emission factors based on a limited number of stack tests
– Condensable PM measurements based on “old” version of EPA
Test Method 202 conducted during method infancy
• Solution:
– Short-term: Develop alternate emission factors based on recent
available test results and research study findings for similar
combustion units on a case-by-case basis
– Long-term: EPA and State agencies should establish more
representative emission factors in AP-42 and/or guidance
Alternate PM Emission Factors
• Wealth of PM stack test data exists for external
and internal combustion units firing a variety of
fuels, but most is not easily accessible for case-bycase analyses for developing alternate emission
factors
• For this analysis, focus is on the New York State
Energy Research and Development
Authority/American Petroleum Institute
(NYSERDA/API) research program findings
Alternate Emissions Factors (cont’d):
NYSERDA/API Research Studies - Background
• NYSERDA/API testing program sponsored by several government and
private organizations with GE Energy and Environmental Research
Corporation providing lion’s share of technical management
• PM emissions testing of natural gas-fired boilers (3), heaters (3), and
combustion turbines (3) occurred over the 2000-2004 period
• Well-controlled testing using EPA Reference and Conditional TMs
– For some of the tests, concurrent measurements made using
Dilution Sampling Method
– Test run sampling time for all methods: 6 hours
• Series of technical reports published in 2004 and available to public
through NYSERDA’s Environmental Monitoring, Evaluation, and
Protection publications website
Alternate Emission Factors (cont’d):
NYSERDA/API Results – Natural Gas-Fired Units
Unit Type
EPA Test Methods
Unit Size
(MMBtu/hr)
Unit
Load
(%)
Dilution
Sampling
Method Total PM2.5
(lb/MMBtu)
Filterable
PM2.5
(lb/MMBtu)
Condensable
PM
(lb/MMBtu)
Total PM2.5
(lb/MMBtu)
C
62.5
70
0.000056
0.000068
0.0012
0.0013
Delta
65
28-39
0.00053
NM
NM
NM
Charlie*
300
95-100
0.00016
0.000055
0.0010
0.0011
0.00025
0.000062
0.0011
0.0012
Test Site
ID
Boiler
Heater
External Combustion Unit Average:
Bravo**
NA
85-100
0.00024
0.00009
0.0030
0.0031
Echo**
NA
59-100
0.00013
NM
NM
NM
0.00019
0.00009
0.0030
0.0031
Turbine
Internal Combustion Unit Average:
Notes: NM = No Measurement; NA = Not Available
*Equipped with SCR, which was in operation during tests
**Equipped with oxidation catalyst and SCR, which was in operation during tests
Alternate Emission Factors (cont’d):
NYSERDA/API Results – RFG-Fired Units
EPA Test Methods
Unit Size
(MMBtu/hr)
Unit
Load
(%)
Fuel S
Content
(ppmv
H2S)
Dilution
Sampling
Method Total PM2.5
(lb/MMBtu)
Filterable
PM2.5
(lb/MMBtu)
Condensable
PM
(lb/MMBtu)
Total PM2.5
(lb/MMBtu)
Unit
Type
Test
Site
ID
Boiler
A
650
57
42
0.00036
0.000025
0.0097
0.0097
Alpha
184.9
85-91
2.8
0.000052
0.00043
0.0079
0.0083
B
114
44
7.7
0.000054
0.00022
0.0046
0.0048
0.00020
0.00023
0.0075
0.0077
0.00029
NM
NM
NM
Heater
External Combustion Unit Average:
Turbine
Golf**
NA
99
28
Notes: NM = No Measurement; NA = Not Available
**Equipped with oxidation catalyst and SCR, which was in operation during tests
Alternate Emission Factors (cont’d):
Revised PM Emissions for 2002 NEI
• In August 2005, EPA stated they would revise PM emissions
in final 2002 National Emissions Inventory (NEI)
• Reason for adjustment was EPA’s belief that AP-42
emission factors for condensable PM were too high
• EPA based their adjustments on the NYSERDA/API research
program results for gas-fired units
• Specific information on assumptions and methodologies
were not made available
Alternate Emission Factors (cont’d):
Revised PM Emissions for 2002 NEI
Emission Factors
2002 NEI
Source Type
PM Emission
Component
(lb/MMft3)
(lb/MMBtu)*
External
Combustion
Units
Filterable PM2.5
Filterable PM10
Condensable PM
0.11
0.2
0.32
0.00011
0.0002
0.00031
AP-42
(lb/MMBtu)
0.0019
0.0019
0.0056
Combustion
Turbines
Filterable PM2.5
Filterable PM10
Condensable PM
0.11
0.2
0.32
0.00011
0.0002
0.00031
0.0019
0.0019
0.0047
%
Reduction
from AP-42
Factor
94
89
94
94
89
93
*Converted from lb/MMft3 to lb/MMBtu assuming a natural gas heat content of 1,020 Btu/ft3
Alternate Emission Factors (cont’d):
WRAP’s Regional Haze Rule Analysis
• Western Regional Air Partnership
(WRAP) is a voluntary organization of
western states, native tribes, and federal
agencies
• WRAP Stationary Sources Joint Forum
used EPA-adjusted NEI factors to develop
baseline and future (2018) PM10 and
PM2.5 emission inventories for regional
haze rule assessments
• State’s regional haze SIPs submitted to
and approved by EPA in 2007-2012
timeframe
Alternate Emission Factors (cont’d):
Minor Source Permitting of Combustion Units
• New Mexico:
– Application for new natural gas-fired simple cycle combustion
turbine equipped with SCR submitted to NMED-AQB in 2010
– NYSDERA/API research studies results used as the basis for
developing alternate total PM (filterable PM + condensable PM)
emission factor
– Alternate emission factor based on analysis of recent stack test
results for same type of turbine, with criteria:
• Lack of any reported unknown contamination or residue in the tests
• Extended run times to collected more PM mass for measurement (ideally,
multiple hours per test run)
– NMED-AQB issued construction permit in June 2011
Alternate Emission Factors (cont’d):
PSD Permitting of Combustion Units
• North Dakota:
– Application for new natural gas-fired combustion turbine
submitted to NDDH in 2012
– NYSDERA/API research program results used as the support for
developing alternate condensable PM emission factor
– Condensable PM emission factor assumed to equal 50% of AP-42
emission factor
– Filterable PM emission rate based on manufacturer’s guarantee for
turbine
– NDDH issued construction permit in February 2013
Emission Factors Summary
Emission Factors (lb/MMBtu)
NYSERDA/API Studies
Unit Type
External
Combustion
Unit
(Boiler or
Heater)
Combustion
Turbine
PM Emission
Component
Natural Gas-Firing
RFG-Firing
EPA 2002
NEI
AP-42
North
Dakota
New
Mexico
DS
Method
EPA TMs
DS
Method
EPA TMs
Filterable PM2.5
-
0.000062
-
0.00023
0.00011
0.0019
-
-
Filterable PM10
-
0.000089
-
0.00042
0.0002
0.0019
-
-
Condensable PMa
-
0.0011
-
0.0075
0.00031
0.0056
-
-
Total PM2.5
0.00025
0.0012
0.00020
0.0077
0.00041
0.0075
-
-
Total PM10
-
0.0012
-
0.0079
0.00051
0.0075
-
-
Filterable PM2.5
-
0.00009
-
-
0.00011
0.0019
0.0051*
0.0012
Filterable PM10
-
0.00029
-
-
0.0002
0.0019
0.0051*
0.0012
Condensable PMa
-
0.0030
-
-
0.00031
0.0047
0.0023
0.0028
Total PM2.5
0.00019
0.0031
0.00029
-
0.00041
0.0066
0.0074
0.0040
Total PM10
-
0.0033
-
-
0.00051
0.0066
0.0074
0.0040
Notes: RFG = Refinery Fuel Gas; DS = Dilution Sampling; TM = Test Method; NEI = National Emissions Inventory
* Based on manufacturer’s guarantee, not on testing results analysis
Concluding Remarks
• The regulated community as well as regulators recognize that
AP-42 emission factors for PM are not the most representative
factors for gas-fired combustion units
• NYSERDA/API research program results, together with actual
stack test data for similar combustion units/fuels, provide good
support for the development of alternate PM emission factors,
especially for condensable PM from low-sulfur fuel-fired units
• Precedent exists for the use of alternate, approvable PM
emission factors for permit applicants
• Efforts need to be made to help regulators understand the need
to establish new, alternate emission factors and guidance so
case-by-case work can be minimized
Concluding Remarks (cont’d)
• For permit applicants, developing and using an alternate,
representative emission factor requires balancing:
– The need to demonstrate compliance with PM2.5
NAAQS in the application, with the need to
demonstrate compliance with permit emission limits in
the future
– The expectation that testing to demonstrate
compliance with permit limits will require careful
method implementation involving extended test run
times, with the associated higher cost of such testing
Thank you!
Louis Corio
[email protected]
Phone: (410) 312-7912
Karen Olson
[email protected]
Phone: (512) 879-6618
Zephyr Environmental
Corporation
Visit us at www.ZephyrEnv.com
and www.HazMatAcademy.com