NTE pursues Connecticut okay for 550-MW Killingly combined cycle project

NTE Connecticut LLC applied Aug. 17 at the Connecticut Siting Council for a Certificate of Environmental Compatibility and Public Need for the construction, maintenance, and operation of a 550-MW, dual-fuel combined cycle facility and associated electrical interconnection switchyard located at 180 and 189 Lake Road, Killingly, Connecticut.

The Killingly Energy Center (KEC) is designed to competitively serve the existing and future demand for electricity generation in Connecticut and throughout the New England regional transmission system. The 73-acre site located off of Lake Road in the Town of Killingly (the KEC Site) is considered uniquely qualified for several reasons, said the application:

  • Existing electric transmission infrastructure extends immediately adjacent to the KEC Site;
  • An interstate natural gas pipeline is located approximately two miles to the north of the KEC Site, with the opportunity to utilize an existing right-of-way that extends in proximity to the KEC Site;
  • Connections to sufficient water and sewer resources are available within approximately 3,100 feet;
  • The power generation elements of the KEC Site are just west of the Town of Killingly’s industrial park, in an area identified in the Town of Killingly’s Plan of Conservation and Development for future industrial use;
  • Development at the KEC Site will result in low air emissions impacts and minimal impact on cultural or other environmentally sensitive areas; and
  • Local officials have been open to the KEC proposal and support economic development.

A 63-acre parcel north and west of Lake Road will support the electric generating facility (the Generating Facility Site), including a 150-foot tall exhaust stack. The electrical switchyard (Utility Switchyard) will be constructed on a 10-acre parcel (the Switchyard Site), located immediately across the street from the Generating Facility Site, south and east of Lake Road. The Utility Switchyard will ultimately be owned and operated by Eversource, and an easement will be granted by NTE to Eversource for the underlying property and access road. Both properties are immediately adjacent to and west of an existing Eversource electric transmission line right-of-way (ROW).

The primary source of fuel for KEC will be natural gas, extending from existing service approximately two miles to the north of the KEC Site. During times of natural gas curtailment or service interruption, KEC will operate on ultra-low sulfur distillate (ULSD) as a backup fuel.

NTE proposes to install one Siemens SGT6-8000H combustion turbine generator (CTG) that will produce approximately 300 MW (nominal). The CTG will incorporate NOX combustion control technologies, including dry-low NOX (DLN) combustors during natural gas firing and water injection during ULSD firing.

Waste heat in the CTG exhaust will be recovered to generate steam in a heat recovery steam generator (HRSG) to power the steam turbine generator (STG). The HRSG will be a multi-pressure, horizontal unit with reheat capabilities and natural circulation. The HRSG will be designed for horizontal gas turbine exhaust flow through vertical tube heat transfer sections, and will have supplemental fuel firing provided by an approximately 920 million British thermal units per hour (MMBtu/hr) natural gas-fired duct burner. The natural gas-fired duct burners will generate additional steam for the STG during periods of high electricity demand.

Selective catalytic reduction (SCR) technology, widely recognized as the most stringent available control technology for NOX emissions from combustion sources, will be installed to control NOx emissions. An oxidation catalyst will be installed to control carbon monoxide (CO) and volatile organic compound (VOC) emissions. The SCR and oxidation catalyst will be located within the HRSG downstream of the CTG and duct burners. Exhaust gases from the HRSG will be released to the atmosphere through a 150-foot tall stack.

The STG will be a 3,600 rpm, tandem compound, reheat steam turbine with a high pressure/intermediate pressure section and double flow low pressure section design. The STG will generate an additional approximately 250 MW of electric power at International Organization for Standardization (ISO) conditions with supplemental duct firing of the HRSG. The STG will be designed to run continuously, but will be capable of operating as a cycling unit to respond to fluctuations in electricity demand. The STG will be located in the turbine building with the CTG.

To minimize the water requirements of KEC, steam from the STG will be condensed in an air-cooled condenser (ACC) with the condensed water sent back to the HRSG. A multi-fan ACC will cool and condense the exhaust steam from the STG. The ACC relies on indirect heat transfer with the ambient air, thereby eliminating the need for substantial water requirements typical of many water-cooled power generating facilities, in which conventional forced-draft wet cooling towers with direct contact with the ambient air results in substantial evaporative water losses. An ACC-equipped facility utilizes approximately 95% less water than a conventional wet-cooled facility, and eliminates a significant source of visual water vapor plume.

The CTG and STG are rated at a nominal 300 MW and 250 MW, respectively. The total of approximately 550 MW of generation will be integrated into the ISO New England electric grid via an electrical interconnection with the existing 345-kV transmission system.

NTE Connecticut is an affiliate of NTE Energy LLC, which is focused on the goal of developing, constructing, owning, and operating power projects across the United States.

Plant will interconnect to the Eversource system

The plant switchyard will consist of two high voltage 345-kV circuit breakers, disconnect switches, and associated bus structures, and will serve to consolidate the output from both synchronous generators (i.e., the full KEC facility) to a single point. From this point, a short three-phase transmission line segment will cross Lake Road, originating from a vertical tangent structure in the collection yard located on the Generating Facility Site, and terminating at a vertical tangent structure located within the Utility Switchyard located on the Switchyard Site, south of Lake Road.

The proposed Utility Switchyard will be located immediately adjacent to Eversource’s 115-kV and 345-kV transmission line ROW, eliminating the need for any new transmission corridor or ROW to supply KEC’s output from the Utility Switchyard to the regional transmission system. The Utility Switchyard will be designed in a three-breaker ring bus configuration to allow for an in-and-out tap of the existing 345-kV transmission line, such that the power generated by KEC can flow through the existing line. The existing Eversource ROW includes two 115-kV transmission lines immediately adjacent to the Switchyard Site, with two 345-kV lines on the opposite side of the ROW. KEC will connect to Eversource’s 345-kV Line 3271, which was installed in 2015.

KEC’s firm delivered natural gas fuel supply will be sourced directly from Algonquin Gas Transmission Co. (AGT) interstate natural gas pipeline, through a firm natural gas fuel supply agreement with Emera, a major New England natural gas fuel supplier. The natural gas interconnection will include a natural gas pipeline lateral approximately 2.8 miles in length, connecting the existing AGT pipeline to KEC within an existing natural gas line lateral ROW owned and operated by Yankee Gas

A project contact is: Mark Mirabito, Vice President, NTE Connecticut LLC, 24 Cathedral Place, Suite 300, St. Augustine, FL 32084, mmirabito@nteenergy.com. 

In addition to NTE, the KEC team of professional firms contributing to this application included: Tetra Tech Inc.; Mott MacDonald LLC; PA Consulting Group Inc.; Killingly Engineering Associates LLC; F.A. Hesketh & Associates Inc.; Haley & Aldrich Inc.; REMA Ecological Services LLC; and Exponent Inc.

The estimated total construction cost for the project is $537 million.

This is one of three new projects for NTE

NTE Energy announced April 15 that it is developing a next round of three natural gas-fired power plants: the Killingly Energy Center, located in Killingly, Conn.; the Reidsville Energy Center, located in Rockingham County, N.C.; and the Pickaway Energy Center, located in Pickaway County, Ohio. The Killingly Energy Center and the Reidsville Energy Center projects are approximately 500 MW each in size, and the Pickaway Energy Center will be approximately 1,000 MW.

These facilities are scheduled to begin construction between 2017 and 2018, and are expected to reach full commercial operation between 2020 and 2021.

Incidentally, NTE Carolinas II LLC on July 29 applied to the North Carolinas Utilities Commission for a Certificate of Public Convenience and Necessity authorizing the construction of the Reidsville Energy Center.

“Following the commencement of construction on NTE’s Kings Mountain Energy Center and Middletown Energy Center, we are excited to announce the next three projects in our portfolio,” said Seth Shortlidge, CEO of NTE Energy, in the April 15 announcement. “We look forward to developing efficient power to fulfill the growing demand for clean, reliable generation.”

NTE’s Kings Mountain Energy Center, located in Cleveland County, N.C., and Middletown Energy Center, located in Butler County, Ohio are currently under construction, with expected commercial operation in 2018. NTE’s Pecan Creek Energy Center, located in West Texas, is expected to commence construction in the fall of 2016.

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.