Document ID: EPA-R07-OAR-2023-0201-0003
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2023-04-26T04:00Z

MO-458
                                                           EPA-R07-OAR-2023-XXX
                                                                               
MEMORANDUM

SUBJECT:	Technical Support Document for Partial Approval/Partial Disapproval to the State Implementation Plan (SIP); State of Missouri-Evergy Lake Road Amendment #2 to Administrative Order on Consent 
	
FROM:		Allie Donohue
			ARD/Analysis, Grants and Partnership Programs Branch

TO:			EPA-R07-OAR-2023-XXX; MO-458

THROUGH: 		Amy Algoe-Eakin, Branch Supervisor
			ARD/Air Permitting and Planning Branch

The Environmental Protection Agency (EPA) is proposing to partially approve and partially disapprove revisions to the Missouri State Implementation Plan (SIP). The EPA received the Missouri Department of Natural Resources' (MoDNR) submission on February 17, 2022, requesting EPA to approve revisions to an Administrative Order on Consent (AOC) for controlling sulfur dioxide (SO2) emissions at the Lake Road Generating Station (Lake Road).

In its submission, MoDNR requested that a 2016 Administrative Order on Consent (hereinafter referred to as "2016 AOC") between the MoDNR and Evergy (formerly Kansas City Power & Light) and Amendment #1 be replaced with Amendment #2 to the AOC in Missouri's SIP. The Lake Road AOC Amendment #2 consolidates all requirements into a single document, adds new fuel restrictions, removes SO2 emission rate limits that are no longer needed due to the updated fuel restrictions, and streamlines reporting requirements. 
 
 The EPA is proposing to approve replacing the 2016 AOC and Amendment #1 in the SIP with Amendment #2, except for paragraph 12.A. of Amendment #2. The changes proposed for approval meet the requirements of the Clean Air Act. The EPA is proposing disapproval of Amendment #2 paragraph 12.A. because it potentially allows fuel oil with a sulfur content greater than the sulfur content limit to be burned on a temporary basis. Paragraph 12.A is not included in the 2016 AOC or Amendment #1 and is therefore severable from Amendment #2.

This technical support document (TSD) discusses our review and analysis of the Lake Road AOC Amendment #2 and provides support for our proposed action.
 
Background

In 2000, MoDNR issued a Consent Decree to the company that owned Lake Road at the time, St. Joseph Light & Power Company. The purpose of the 2000 Consent Decree was to
support a 2001 attainment demonstration for the 1971 24-hour SO2 National Ambient Air Quality Standard (NAAQS) in the area surrounding Lake Road. EPA approved the 2000 Consent Decree into Missouri's SIP in November of 2001.

Since the issuance of the original Consent Decree, Lake Road implemented multiple changes, including changing ownership from St. Joseph Light & Power Company to Kansas City Power and Light (KCPL). MoDNR incorporated many of these changes into an AOC that was issued to KCPL in 2016 (2016 AOC) and subsequently amended the AOC in 2018 (Amendment #1). EPA approved the 2016 AOC and Amendment #1 into Missouri's SIP in August of 2019.

Evergy became the current owner and operator of Lake Road after KCPL and Westar Energy merged to become Evergy in 2018. In 2021 MoDNR and Evergy revised the AOC for Lake Road by issuing Amendment #2 that consolidates all requirements into a single document, lowers the fuel oil sulfur content limit from 500 ppm to 15 ppm, eliminates SO2 emission limits that are no longer necessary due to the more stringent fuel oil sulfur content limits, makes the retirement of Boiler No. 3 permanent and enforceable, and streamlines reporting and record keeping requirements. Amendment #2 does not revise the SO2 emission rate limit of 1.349 pounds per million British thermal units (lb/MMBtu) for Boiler No. 5. Amendment #2 also adds language in paragraph 12.A. that allows MoDNR to grant temporary exemptions to the fuel oil requirements due to unforeseen circumstances. 

On June 22, 2010, EPA strengthened the SO2 NAAQS by establishing a new 1-hour SO2 standard of 75 parts per billion (ppb). The 2010 SO2 standard is based on the three-year average of the annual 99th percentile of 1-hour daily maximum concentrations. The 2010 SO2 standard replaced the previous 24-hour and annual SO2 standards promulgated in 1971. EPA has designated Buchanan County, where Lake Road is located, as attainment/unclassifiable, meaning the area surrounding Lake Road complies with the 2010 SO2 standard.

Fuel Requirements

In the 2016 AOC and Amendment #1, the fuel oil sulfur content limit for Boiler Nos. 1, 2, 4, and 6, and Combustion turbine Nos. 5, 6, and 7 was 500 parts per million (ppm), or 0.05% by weight. Amendment #2 lowers the allowable sulfur content for the fuel oil in these emissions units to 15 ppm, or 0.0015% by weight. In addition, the previous AOC did not define fuel oil. Amendment #2 specifies that fuel oil includes but is not limited to the following fuels so long as the sulfur content limitation is met:  No 2. fuel oil; diesel fuel; biodiesel; blends of these fuels; and other fuels approved by MoDNR that meet the sulfur content limit of 15 ppm.

Both Amendment #1 of the 2016 AOC and Amendment #2 list low sulfur coal as the
primary fuel for Boiler No. 5. However, Amendment #1 did not include a definition for low sulfur coal. Instead, it included an equation for demonstrating the sulfur content of the coal burned in Boiler No. 5 met the numeric SO2 emission rate limit of 1.349 pounds per million British thermal units (lb/MMBtu). Amendment #2 defines low-sulfur coal as coal with an SO2 emission potential of 1.349 lb/MMBtu, which is unchanged from Amendment #1, and eliminates the equation. 

Amendment #2 removes the fuel requirements for Boiler No. 3 that were in the previous 2016
AOC and Amendment #1 because Boiler No. 3 has been retired. Amendment #2 also prohibits the future operation of Boiler No. 3.

Amendment #2 continues to allow propane to be burned in place of No. 2 oil or coal in Boilers 1, 2, 4, 5, and 6 for light off and flame stabilization during periods of natural gas curtailment and for testing of the propane combustion system. This provision is unchanged from the 2016 AOC and Amendment #1.

Below is a summary table comparing the fuel requirements in the 2016 AOC and Amendment #1 compared to Amendment #2. As stated in Amendment #2 paragraph 12., the terms "primary" and "secondary" are indicators of priority of typical usage but do not restrict the type of fuel combusted.  

  Table 1  - 2016 AOC and Amendment #1 Versus Amendment #2 Fuel Requirements
                                     Unit
                          2016 AOC & Amendment #1
                                 Amendment #2
                                       
                                 Primary Fuel
                                Secondary Fuel
                                 Primary Fuel
                                Secondary Fuel
                          Boiler Nos. 1, 2, 4, and 6
                                  Natural Gas
                     No. 2 Fuel Oil (500 ppm Sulfur Limit)
                                  Natural Gas
                                   Fuel Oil
                             (15 ppm Sulfur Limit)
                                 Boiler No. 3
                                  Natural Gas
                                     None
                                      N/A
                                      N/A
                                 Boiler No. 5
                               Coal (low sulfur)
                            (1.394 lb/MMBtu Limit)
                                  Natural Gas
                                       
                               Coal (low sulfur)
                            (1.394 lb/MMBtu Limit)
                                  Natural Gas
                           Combustion Turbine No. 5
                                  Natural Gas
                                No. 2 Fuel Oil
                            (500 ppm Sulfur Limit)
                                  Natural Gas
                                   Fuel Oil
                             (15 ppm Sulfur Limit)
                        Combustion Turbine Nos. 6 and 7
                                No. 2 Fuel Oil
                            (500 ppm Sulfur Limit)
                                  Natural Gas
                                       
                        Fuel Oil (15 ppm Sulfur Limit)
                                  Natural Gas

Amendment #2 adds a new temporary exemption for fuel requirements in paragraph 12.A. This language is not included in the 2016 AOC or Amendment #1. In discussions between the EPA and MoDNR, the state clarified that the intent of Amendment #2 paragraph 12.A. is to provide flexibility for Lake Road to temporarily utilize fuel oils other than those specified in Table 1, including fuel oils with a sulfur content greater than 15 ppm, due to supply issues or other unforeseen circumstances. Because the new exemption language potentially allows Lake Road to burn fuel oil with a sulfur content greater than the sulfur content limit of 15 ppm, the EPA is proposing to disapprove paragraph 12.A. The language being proposed for disapproval is as follows:

      Amendment #2, Paragraph 12.A., Temporary Exemptions for Fuel Requirements  -  
      Evergy may request, and the Department may grant, temporary exemptions to the fuel requirements listed in Table 1 in the event an unforeseen circumstance would cause a fuel not listed in Table 1 to be substantially more reasonable during a temporary time period. For this exemption to apply, Evergy must receive written authorization from the Department prior to the use of such alternative fuel. To qualify for this temporary exemption, Evergy must notify the Department in writing. This notification must include an explanation of the unforeseen circumstance, the alternative fuel they are seeking the exemption to use, and the reason the unforeseen circumstance has made the use of such alternative fuel substantially more reasonable than the fuels listed in Table 1. The notification must also include the actions that Evergy has taken and plans to take to address the issue, and the amount of time for which they are requesting the exemption. The Department maintains the discretion to allow an exemption pursuant to this paragraph, including the duration of such exemption.

EPA Analysis:
With the exception of Amendment #2 paragraph 12.A., the revised fuel requirements in Amendment #2 are more stringent than or equivalent to the SIP-approved fuel requirements in the 2016 AOC and Amendment #1. Amendment #2 paragraph 12.A. potentially allows Lake Road to burn fuel oil with a sulfur content greater than the new fuel oil sulfur content limit of 15 ppm. For these reasons, the EPA is proposing to approve the new fuel requirements in Amendment #2 and disapprove paragraph 12.A. of Amendment #2. 

SO2 Emission Limitations

The 2016 AOC and Amendment #1 included a table with numeric SO2 emission rate limits in both lb/MMBtu and pounds per hour (lb/hr) for the six boilers (Boiler No. 3 included) and the three combustion turbines at Lake Road. The latest version of the SO2 emission rate limit table is Table 1 in Amendment #1. Amendment #2 removes the SO2 emission rate limit table, which eliminates the numeric SO2 emission rate limits for all boilers and combustion turbines, except for Boiler No. 5. Amendment #2 retains the SO2 emission rate limit of 1.349 lb/MMBtu Boiler for Boiler No. 5. Amendment #2 does not include an SO2 emission limit for Boiler No. 3 because it has been permanently retired.

In order to determine if removal of the emission rate limits results in an SO2 emissions increase at Lake Road, the EPA calculated maximum allowable emission rates allowed under Amendment #2 based on the new fuel requirements discussed in the previous section of this TSD. For this analysis, each emission unit was assumed to combust the fuel with the highest potential SO2 emissions listed in Table 1 of this TSD for the unit. Specifically, Boiler Nos. 1, 2, 4, and 6 and Combustion Turbine Nos. 5, 6, and 7 were assumed to combust only fuel oil, and Boiler No. 5 was assumed to combust only coal. 

Potential SO2 emissions in lb/MMBtu were first calculated for the fuel oil units based on EPA's Compilation of Air Emission Factors (AP-42), Chapter 1.3 Fuel Oil Combustion, Table 1.3-1. Criteria Pollutant Emission Factors for Fuel Oil Combustion. SO2 emission rates in pounds per thousand gallons (lb/10[3] gal) were calculated using Equation 1, which is the SO2 emission factor equation for No. 2 fuel oil for boilers > 100 million Btu/hr.

      Equation 1:		SO2 Emission Ratelb103gal=142S

                        Where:  S = weight % of sulfur

Based on the Amendment #2 fuel oil sulfur content limit of 15 ppm (0.0015% by weight), 0.0015 was used as the value of S in Equation 1 for Boiler Nos. 1, 2, 4, and 6 and Combustion Turbines No. 5, 6, and 7. 

Equation 2 was then used to convert the emission rate to an energy basis (lb/MMBtu) by dividing the emission rate in lb/10[3] gal by the heating value (HV) for No. 2 fuel oil. AP-42 Chapter 1.3 suggests a default HV of 140 MMBtu/10[3] gal for No. 2 fuel oil.

      Equation 2:		  SO2 Emission RatelbMMBtu= SO2 Emission Rate lb103 galHV

					Where:  HV=heating value (MMBtu/103gal)

The final step was to calculate maximum hourly SO2 emissions in lb/hr for the fuel oil units and combustion turbines by multiplying the emission rates in lb/MMBtu by the maximum hourly design rates (MMBtu/hr) for each unit as shown in Equation 3. 
      
Equation 3:		SO2 Emission Rate lbhr= SO2 Emission RatelbMMBtu* Hin 
 
                        Where:  Hin=Max Hourly Design Rate MMBtuhr

The maximum hourly heat input rates for each boiler and combustion turbine were obtained from the Lake Road Title V Operating Permit Number OP2007-005. These values are summarized in in Table 2.

                         Table 2  -  Heat Input Rates
                                     Unit
                        Max Heat Rate Input (MMBtu/hr)
                              Boiler Nos. 1 and 2
                                      192
                            Boiler No. 3 (retired)
                                      238
                                 Boiler No. 4
                                      311
                                 Boiler No. 5
                                      336
                                 Boiler No. 6
                                      980
                           Combustion Turbine No. 5
                                      876
                           Combustion Turbine No. 6
                                      275
                           Combustion Turbine No. 7
                                      296

Using Equations 1 through 3, example calculations based on Boiler Nos. 1 and 2 combusting fuel oil with a sulfur content of 15 ppm (0.0015% by weight) are as follows:

Example 1:	     SO2 Emission Ratelb103gal=142*0.0015=0.213 lb103gal
SO2 Emission Rate lbMMBtu=0.213 lb103gal140 MMBtu103 gal=0.00152 lbMMBtu

         SO2 Emission Rate lbhr= 0.00152 lbMMBtu*192 MMBtu/hr=0.29lbhr
                                       
For Boiler No. 5, Amendment #2 includes an SO2 emission rate limit of 1.349 lb/MMBtu, which is unchanged from the 2016 AOC and Amendment #1. In this analysis, the 1.349 lb/MMBtu limit was converted to maximum hourly emissions (lb/hr) using Equation 3. The calculation is shown in Example 2 below.

Example 2:	     
SO2 Emission Rate lbhr= 1.349 lbMMBtu*336 MMBtu/hr=453.26lbhr

Table 2 presents a summary of EPA's analysis and compares the emission rate limits in the 2016 AOC and Amendment #1 to the calculated maximum allowable SO2 emission rates under Amendment #2. Note that Boiler No. 6 previously only had an hourly emission rate limit (lb/hr) in the 2016 AOC and Amendment #1. Maximum allowable SO2 emission rates under Amendment #2 were not calculated for Boiler No. 3 because it has been permanently retired.

      	Table 3  -  2016 AOC and Amendment #1 Emission Rate Limits Versus 
                 Amendment #2 Maximum Allowable Emission Rates
                                     Unit
                           Fuel Assumed in Analysis
                          2016 AOC & Amendment #1
                                 Amendment #2
                                       
                                       
                           SO2 Emission Rate Limits 
                                  (lb/MMBtu)
                       SO2 Emission Rate Limits (lb/hr)
Maximum Allowable SO2 Emission Rates & Boiler No. 5 SO2 Emission Rate Limit (lb/MMBtu)
                 Maximum Allowable SO2 Emission Rates (lb/hr)
Boiler Nos. 1 and 2
                                   Fuel oil
                                    0.0524
                                     10.06
                                    0.00152
                                     0.29
Boiler No. 3
N/A  -  permanently retired, so not included in max allowable emission rate calculations
                                    0.0006
                                     0.15
                                      N/A
                                      N/A
Boiler No. 4
                                   Fuel oil
                                    0.0524
                                     16.29
                                    0.00152
                                     0.47
Boiler No. 5
                                     Coal
                                     1.349
                                    453.26
                                     1.349
                                    453.26
Boiler No. 6
                                   Fuel oil
                                    ------
                                     1400
                                    0.00152
                                     1.49
Combustion Turbine No. 5
                                   Fuel oil
                                    0.0511
                                     44.30
                                    0.00152
                                     1.33
Combustion Turbine No. 6
                                   Fuel oil
                                    0.0511
                                     14.05
                                    0.00152
                                     0.42
Combustion Turbine No. 7
                                   Fuel oil
                                    0.0511
                                     15.12
                                    0.00152
                                     0.45

EPA Analysis:
Based on the new, more stringent fuel oil sulfur content limits in Amendment #2, the maximum allowable SO2 emission rates for all units that combust fuel oil are less than the respective SO2 emission rate limits in the 2016 AOC and Amendment #1. The SO2 emission rate limit of 1.349 lb/MMBtu for Boiler No. 5 in Amendment #2 is unchanged from Amendment #1, so it follows that the calculated maximum allowable hourly emission rate for this unit is equivalent to the hourly emission rate limit in Amendment #1. For these reasons, the EPA proposes to conclude that removing the table of SO2 emission rate limits contained in the 2016 AOC and Amendment #1 from the SIP will not result in increased SO2 emissions at the Lake Road facility. 

Reporting and Recordkeeping Requirements

The 2016 AOC and Amendment #1 required Lake Road to sample every coal shipment received to determine the sulfur content and calculate the SO2 emission potential of the coal for Boiler No. 5.  Fuel suppliers were also required to certify the sulfur content of all fuel oil shipments. Lake Road was required to submit this information to MoDNR every calendar quarter. 
Amendment #2 eliminates the requirement for both Lake Road and the fuel suppliers to sample every fuel oil and coal shipment received. It also eliminates the requirement for Lake Road to calculate the SO2 emission potential for Boiler No. 5. Instead, Amendment #2 requires records from the fuel suppliers to be used to demonstrate compliance with the fuel requirements. Amendment #2 requires Lake Road to maintain records demonstrating the sulfur content of all coal shipments and fuel oil deliveries meet the sulfur content requirements of the AOC and submit them to MoDNR on an annual basis.

EPA Analysis:
The EPA is proposing to approve the reporting and record keeping provisions in Amendment #2 because they continue to require Evergy to maintain sufficient records to demonstrate compliance with the AOC requirements for Lake Road.

Lake Road SO2 Emissions

In its submission, MoDNR included an analysis of SO2 emissions from the Lake Road facility between 2002 through 2020. MoDNR's analysis, presented in Figure 1 below, demonstrated that Lake Road SO2 emissions have decreased by 94.8 percent from 2002 through 2020, primarily attributable to the 2000 Consent Decree and the fuel requirements provided in the 2016 AOC, Amendment #1, and Amendment #2. MoDNR states that Amendment #2 will ensure the SO2 emissions decreases at Lake Road over the past 20 years remain permanent and further assist with maintenance and attainment of both the 1971 and 2010 SO2 NAAQS. 

 
Figure 1. Lake Road SO2 Emission Trend (Source:  MoDNR)
 
 EPA Analysis:
 The EPA reviewed the MoDNR's Lake Road SO2 emissions analysis and determined the trend is consistent with available data in the National Emissions Inventory and the EPA's Clean Air Markets Division (for Boiler No. 6). The EPA proposes to conclude that Amendment #2, with the exception of paragraph 12.A., will not result in an increase in SO2 emissions at the Lake Road facility. The EPA proposes to disapprove Amendment #2 paragraph 12.A. because it potentially allows the facility to burn fuel oil with sulfur content that exceeds the 15 ppm sulfur content limit on a temporary basis.

Record of Rulemaking

                 Table 3  -  Amendment #2 Record of Rulemaking
                             Record of Rulemaking
                   Missouri Department of Natural Resources
Notice of Proposed Action
November 1, 2021
Public Hearing
December 2, 2021
Adopted by Missouri Air Conservation Commission (MACC)
January 27, 2022
Effective date of AOC Amendment #2
October 18, 2021

SIP Submittal sent to EPA Region 7 by MoDNR
February 17, 2022
Rule package received by EPA
February 17, 2022