New York ISO says shutdown of two coal plants can be worked around

The New York ISO sent an Oct. 30 letter to the New York State Public Service Commission saying that grid fixes can compensate for the shutdown of the coal-fired Dunkirk and Huntley power plants.

On Aug. 28, the comission requested that NYISO determine whether the proposed retirement of NRG Energy’s (NYSE: NRG) Huntley plant, effective March 1, 2016, and the mothballing of NRG Energy’s Dunkirk units, effective Jan. 1, 2016, would have an adverse impact on the reliability of the New York State transmission system. The NYISO and National Grid responded on Sept. 24 that further analysis was necessary and a follow-up response would be filed by Oct. 30.

“A coordinated analysis by National Grid and the NYISO has been performed to determine impacts to reliability on both the local transmission system and the Bulk Power System,” said the Oct. 30 letter. “Based upon the expectation of the timely completion of the National Grid upgrades (noted below) and that no other changes occur to the current and planned status of the New York electric system, reliability will be maintained through at least the year 2020 if Dunkirk is mothballed January 1, 2016 and Huntley is retired March 1, 2016.

“National Grid informed the NYISO of an update to its local transmission plan to install capacitor banks at the Huntley 230 kV station by June 1, 2016. National Grid also informed the NYISO of possible system configuration changes and relay adjustments associated with the 23 kV load station. With various possible combinations of capacitor banks, system configurations, and relay settings, there would be no reliability violations. Prior to the update of National Grid’s local transmission plan, National Grid and the NYISO identified post-contingency low voltage issues associated with a 23 kV load connected to the 230 kV system adjacent to the Huntley station. These voltage issues would be observed on the existing system under high load conditions if Huntley were retired; the status of the Dunkirk generating units 2, 3, and 4 does not materially affect the observed voltage issues.

“National Grid has proposed adding series reactors to the most constraining 230 kV lines north of Huntley, with a planned in-service date of June 1, 2016, to improve the total Niagara Power Project and Ontario import energy deliverability. An important operational consideration related to the proposed retirement of Huntley and mothballing of Dunkirk is the impact to the Niagara Power Project and Ontario import energy deliverability under normal day-to-day transfer criteria. NYISO studies indicate that the total Niagara Power Project and Ontario import energy deliverability would be reduced to approximately 2,000 MW under forecast peak load conditions, a reduction of over 800 MW compared to the existing system. These constraints would be much greater under transmission outage (N-1-1) conditions.

“The series reactors would improve the total Niagara Power Project and Ontario import energy deliverability, but there would still be a reduction compared to the levels of energy deliverability that exist today with Dunkirk Unit 2 and both Huntley units available. This reduction in energy deliverability will persist until permanent solutions are in place, to be addressed in response to the Western New York Public Policy Transmission Need. In the interim, the NYISO and National Grid are considering a temporary operating procedure to allow the constraining National Grid 230 kV lines to be secured to the higher short-term emergency ratings, similar to the existing NYPA Niagara runback procedure, thus improving Niagara Power Project and Ontario import energy deliverability.

“The NYISO also assessed the resource adequacy of the overall system with Huntley retired and Dunkirk mothballed. Based on the NYISO 2014 Comprehensive Reliability Plan and accounting for the National Grid upgrades, it is expected that the one-day-in-ten-years Loss of Load Expectation (LOLE) criterion, which measures the probability of disconnecting firm load due to a resource deficiency, will not be exceeded through at least the year 2020.

“National Grid’s installation of the capacitor banks and modifications associated with the 23 kV load station are necessary to maintain reliability in the near-term. The NYISO has requested National Grid to provide bi-weekly status updates regarding the progress of that work until it is complete, and will continue to assess whether a Reliability Need will arise on the Bulk Power System or local transmission system. In order to minimize potential reductions in Niagara Power Project and Ontario import energy deliverability, the NYISO also recommends that National Grid advance the completion of the proposed series reactors provided this work does not affect the in-service date for the capacitor banks.”

Huntley was the subject of an Aug. 25 shutdown notice

The PSC’s inquiry was at least in part prompted by an Aug. 25 notice from NRG Energy that it intends to retire Huntley Units 67 and 68, located in Tonawanda, New York, effective March 1, 2016. Also, NRG advised the commission on Aug. 25 that it will mothball the remaining Dunkirk unit, beginning Jan. 1, 2016. National Grid and NRG currently have a Reliability Support Service Agreement (RSSA) for Dunkirk Unit 2 that expires Dec. 31, 2015.

Said the Aug. 28 letter from the PSC ordering a study: “Specifically, one study should assess the retirements of Huntley Units 67 and 68, combined with the mothballing of all Dunkirk units. The second study should assume that the Huntley Units 67 and 68 remain in-service after March 1, 2016, and that all the Dunkirk units are mothballed after January 1, 2016. Finally, a third study should assume that the three Dunkirk Units (2, 3, and 4) are in-service after March 1, 2016, and the Huntley Units 67 and 68 are retired, effective March 1, 2016.

“Further, in light of NRG’s decision to put on hold the [coal-to-gas] refueling project of three of its Dunkirk generating units and in order to better understand the changed circumstances, if any, in Western NY affecting National Grid’s transmission system and to ensure that electric customers receivesafe and reliable electric service, National Grid should explain electric system changes or developments that have occurred that affect the need and timing for the transmission projects that were considered avoidable, assuming the Dunkirk refueled units are in-service in September 2015.”

Huntley Units 67 and 68 are coal-fired units, with 218 MW of nameplate capacity apiece, that began operating in 1957 and 1958, respectively. The units are located in Tonawanda, N.Y., and are interconnected to the National Grid system in NYISO’s Zone A.

“The current power prices and market conditions in New York State are such that it is no longer economical for NRG to continue operating the Units,” said the Aug. 25 notice from NRG. “Thus, because the facility is not currently economic and is not expected to be economic, NRG intends to retire the units. Should circumstances change, NRG will notify all parties to this notice.”

Dunkirk Power owns and operates a coal-fired station in Dunkirk, New York, made up of a (nameplate) 100-MW Unit 1, a 100-MW Unit 2, a 217.6-MW Unit 3, and a 217.6-MW Unit 4, and is a generation-owning entity that sells its energy, capacity and ancillary services in the New York ISO-administered wholesale power market.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.