UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                                   REGION 1
                        5 Post Office Square, Suite 100
                            Boston, MA  02109-3912

Memorandum

Date: 		March 21, 2017
	
Subject:	Technical Support Document (TSD) supporting removal of Rhode Island NOx Budget Trading Program (NBP) from Rhode Island SIP

From: 		Alison Simcox, PhD, Environmental Scientist/Engineer

Thru: 		Anne Arnold, Manager
      Air Quality Planning Unit

To: 		Docket for Removal of Rhode Island NOx Budget Trading Program
		(EPA-R01-OAR-2016-0092)

The Environmental Protection Agency (EPA) is taking action on a request from the Rhode Island Department of Environmental Management to remove Air Pollution Control (APC) Regulation 41, "NOx Budget Trading Program" (NBP), from its State Implementation Plan (SIP).  This request was submitted on October 6, 2014, as a formal SIP revision. This technical support document (TSD) gives EPA's analysis of maximum NOx emissions allowed under the applicable sources' Title V permits, which contain SIP-derived NOx emissions limits, for the five sources that were subject to Rhode Island's NBP: Ocean State Power, Pawtucket Power Associates, Dominion Energy Manchester Street, Inc., Tiverton Power Inc., and Entergy Rhode Island State Energy, L.P. (Table 1).

Example Calculation
 
This example calculation is for the first facility shown on Table 1 below.  Ocean State Power has four permitted emission units: G001, G002, G003 and G004.  Each of these consists of a 105 megawatt (MW) combustion turbine capable of burning #2 fuel oil and natural gas (NG). Under the facility's Title V permit, during oil firing, the four turbines can collectively emit up to 4000 pounds (lbs) of NOx each month. During NG firing, the maximum NOx emission rate from each flue = 37.4 lbs/hr when both turbines in a combined cycle system are operating.

Under the Title V permit, however, oil firing is only allowed from 1 October to 30 April (i.e., not during the ozone season).  Therefore, assume NG firing in all four turbines for the entire ozone season.
1 ton = 2000 lbs
1 day = 24 hours
Ozone season (May 1  -  September 30) = 153 days

Therefore,
Max NOx emissions during ozone season = ((4*37.4)*24)/2000)*153 = 274.7 tons

Table 1  -  Maximum NOx Emissions allowed under Title V operating permits
          (permits included in docket)

                                 Facility Name
                                   Unit ID #
                                   Type Unit
                               NOx Control Tech
            Permit Allowable Ozone Season (OS) Emissions (NOx tons)
          Title V permit citation to Rhode Island SIP emission limits
                                   Comments
Ocean State Power
G001, G002, G003, G004, 
Each unit: 105 MW combustion turbine; NG & Oil
                                     SCR**
                                     274.7
PSD permit:
RI-PSD-1(A)(1)(a)(2)


Oil firing only allowed from 1 October to 30 April (i.e., not during ozone season). Max NOx emission rate from each unit = 37.4 lb/hr (149.6 lb/hr from 4 turbines).
Max OS NOx = (((4*37.4)*24)/2000)*153
Pawtucket Power
C0001
68 MW combustion turbine combined cycle unit w duct firing; burns #2 fuel oil and NG
                                      SCR
                                     41.6
Approval Nos.
948 & 950(A)(2)(a)(2), (A)(1)(a)(2) and (B)(1)
The permit limits oil firing to 3,614,000 gallons (about 1000 hours or 42 days).
Max OS NOx = 
((((17.4*24)/2000))*111)+(((36.5*24)/2000)*42)

Dominion Energy Manchester Street
G009, G010, G011, 
Each unit: 119.05 MW combustion turbine; burns #2 fuel oil and NG
                                      SCR
                                     261.6
PSD permit:
RI-PSD-4(A)(1)(a)(2)

NG: Max NOx from stack = 47.5 lb/hr; 
Oil firing only allowed from 1 October to 30 April (i.e., not during ozone season).
Max OS NOx = (((3*47.5)*24)/2000)*153
Tiverton Power
G001
190.55 MW combustion turbine; burns NG
                                      SCR
                                     41.8
PSD permit:
RI-PSD-5(A)(1)(d)

Max NOx from flue = 22.76 lb/hr; max heat input rate = 1943.4 mmBTU/hr. 
Max OS NOx = (((22.76*24))/2000)*153 
Entergy Rhode Island State Energy
G001, G002
Each unit: 185 MW Combustion turbine; burns NG
                                      SCR
                                     62.4
PSD permit:
RI-PSD-6(A)(2)(a)(2)



Max with duct burners firing = 17.0 lbs/hr.  
Max OS NOx = ((((17.0*2)*24))/2000)*153
Total
 
 
                                       
                                    682.1*

 

*Actual NOx emissions for the five sources for the 2016 ozone season totaled 221 tons, as reported by EPA's Clean Air Markets at https://ampd.epa.gov/ampd/.
** SCR = Selective Catalytic Reduction


