Public Service ofNewHampshire Schiller Station 400 Gosling Road, Portsmouth,NH 

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A. Introduction Final NOxRACT ORDER ARD-06-001 August 4, 2006

This NOx RACT Order is issued by the NewHampshire Department ofEnvironmental Services, AirResources Division, to Public Service ofNewHampshirepursuantto RSA 125-C.

B. Parties 1. The New Hampshire Department of Environmental Services, Air Resources Division ("DES"), is a duly constituted administrative agency ofthe State ofNew Hampshire having its principal offices at 29 Hazen Drive, Concord, NH 03302-0095, telephone number (603) 271-1370. 2. Public Service of New Hampshire (PSNH), a subsidiary ofNortheast Utilities, is a New Hampshire Corporation, having a mailing address of 780 North Commercial Street, Manchester, NH03101. C. Statements ofFact and Law 1. PSNH operates the Schiller Station Power Facility (Schiller Station) located at 400 Gosling RoadinPortsmouth,NH. 2. Schiller Station is a 153 megawatt fossil fuel fired electric generating facility, owned and operated by PSNH. The power generating equipment is comprised of three utility boilers (Units #4, 5, and 6), one combustion turbine operating as a load shaving unit, and an emergency generator. 3. On January 30, 2004, PSNH applied for a TemporaryPermitto replace the Unit#5 coal-fired boiler with a new 50 megawatt utility boiler and a secondary coal crusher at Schiller Station. The newutility boiler ("NWPP Boiler") will be a circulating fluidized bed (CFB) design and will be capable of combusting wood or coal. The NWPP Boiler will utilize the Unit #5 generator and turbine. To preheat the furnace fluidized bed material priorto combusting the solid fuel, a natural gas-fired burner system will be used during startup. The startup burner system consists ofone natural gas-fired duct burner.Public Service of New Hampshire ARD-06-001 August4, 2006 Page 2 o(4 

### 4. Effective May 20, 1994, DES adopted New Hampshire Administrative Rule PART Env-A 1211 NITROGEN OXIDES (NOx). Effective October 31, 2002, DES revised and adopted New Hampshire Administrative Rule PARTEnv-A 1211 NITROGEN OXIDES (NOx). 5. Env-A 1211.03 establishes NOx emission limitations for specific types of utility boilers. Env-A 1211.03 does not establish emission limitations for CFB type boilers; therefore, PSNH was required to submit a request for Alternative RACT Emission Limits pursuant to Env-A 1211.15. 6. On May 28, 2004, PSNH submitted a request for alternative RACT emission limit pursuant toEnv-A 1211.15 7. Pursuant to Env-A 1211.15(c)(l), PSNH conducted a study of the technological and economic feasibility of NOx control techniques, including low NOx burners, overfire air, flue gas recirculation, natural gas reburn, burners out of service, use of alternative fuels, selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). PSNH proposes the use ofthe circulating fluidized bed technology, which is recognized as a low emission, advanced solid fuel combustion technology. The formation ofNOx in the CFB boileris reduced as aresult ofthe lowcombustiontemperatures and low excess air withinthe fluidized bed. While both natural gas rebum and flue gas recirculation are theoretically technically feasible for wood and oil fired boilers, the CFB boilertechnology is not designed to utilize such methods ofNOx reduction. The use oflow-NOx burners and burners out of service are nottechnically feasible as NOx control options for the proposed CFB boiler. The use ofalternative fuels is also not an optionfor NOx control from the boiler. 8. PSNH contends that the only two technically feasible control techniques available for the CFB are SCR and SNCR. PSNH concluded that SCR would be economically infeasible because the high particulate loading in the gas stream would require increased capital, operating and maintenance costs to pretreat the particulate upstream ofthe SCR. The only viable NOx control technique is SNCR because it can operate effectively with a gas stream with high particulate loading. 9. PSNH proposes to use an SNCR system where urea will be injected into the boiler furnace, where it is converted to ammonia. The NOx will react with the ammonia and form nitrogen gas and water. 10. Although PSNH did not specifically address the use of ERCs or DERs as an em1sswn reduction strategy, it is an economically viable option. However, the use of a control technique, such as SNCR, will result in a greater overall reduction inNOx. 11. In 

### PSNH's Request for Alternative RACT Emission Limits, PSNH proposes to use circulating fluidized bed boiler technology with SNCRresulting in aNOx emission factor of 0.075 lb!MMBtu.Public Service of New Hampshire ARD-06-001 

### D. Order August4, 2006 Page 3 of4

Baseduponthe above findings and determinations, DES hereby orders PSNH Schiller Station as follows: 

### 1. Install and operate the CFB boiler. 2. Install and operate the SNCR as necessaryto comply withtheNOx emissionrate whenthe CFB boiler is inoperation. 3. Comply with a 0.075 lbiMMBtuNOxemissionrate for the CFB boiler. 4. Conduct initialperformance tests in accordance withEnv-A 802 and 803 within 60 days of achieving the maximumproductionrate, butno laterthan 180 days from start-up (first firing ofsolid fuel). 5. Use the continuous emissions monitoring systems to determine continuous compliance with theNOx emissionrate. 6. Continueto comply withthe NOxRACT OrderARD-98-001 Conditions D.l.c. andD.l.d., i.e., non-ozone seasonNOx cap of8,208 tons and ozone seasonNOx cap of3,727tons for the combinedNOx emissions from MK1, MK2, NTI, SR4, SR5, and SR6. 7. Comply withthe recordkeeping andreportingrequirements ofEnv-A 900. Please address any correspondence and communication inreference to this Orderto the following: Douglas C. Laughton NHDES, Air Resources Division Bureau ofPermitting & Environmental Health 29 HazenDrive P.O. Box 95 Concord, NH 03302-0095 (603) 271-!370

Robert R. Scott,Director Department ofEnvironmental Services AirResources DivisionPublic Service of New Hampshire ARD-06-001

cc: Timothy Drew, PIP Office David Conroy, US EPA Town Selectmen, Portsmouth RRS/dcl

Final NWPP NOx RACT Order August 4, 2006 August4, 2006 Page 4 o(4