Duke wants to add 84 MW of ‘blackstart’ turbines at its Sutton plant in North Carolina

Duke Energy Progress applied April 15 at the North Carolina Utilities Commission for approval of two “blackstart” gas-fired turbines, with a combined capacity of 84 MW, at its Sutton power plant located near Wilmington, N.C.

Mark E. Landseidel, Director of Project Development and Initiation in the Project Management and Construction Department of Duke Energy (NYSE: DUK), said in supporting testimony: “The Sutton Blackstart CT Project will consist of two new nominal 42 MW simple-cycle combustion turbine dual-fuel electric generating units and related transmission facilities to be located at the Company’s existing L.V. Sutton Energy Complex in New Hanover County, approximately four miles north of Wilmington.

“The Sutton Blackstart CT Project will provide peaking generating capacity to the Duke Energy Progress system, along with critical blackstart and fast-start capability services. The Project is scheduled to begin commercial operation in the summer of 2017.

“The Company has three existing CTs at the Sutton Plant totaling 61 MW, which provide peaking generation to the Company’s customers, as well as regional blackstart capability and tertiary backup power services for the Brunswick Nuclear Plant. Sutton CT Unit 1 is a 11 MW blackstart unit that began operation in 1968; Unit 2A is a 24 MW non-blackstart unit that began operation in 1969; and Unit 2B is a 26 MW blackstart unit that began operation in 1969.

“Duke Energy Progress plans to retire Units 1, 2A and 2B after completion of the Sutton Blackstart CT Project. A three-unit 553 MW coal plant at the site was retired in 2013, when the existing 622 MW combined cycle combustion unit began commercial operation. The Sutton Blackstart CT Project will be sited adjacent to the existing combined cycle unit.

“The simple cycle generating facility will use two aero-derivative combustion turbine generators to produce electricity. Aero-derivative turbines were originally developed for aviation jet propulsion and adapted to provide shaft power to an electric generator. Aero-derivative turbines provide fast -start capability, fast ramp rates, greater stop/start flexibility, and better fuel efficiency than large frame gas turbines. The turbines will be capable of burning natural gas or ultra-low sulfur diesel fuel. The facility will be capable of starting in transmission system blackout conditions. The facility will include two 100% redundant ultra-low diesel fired diesel engines to provide blackout starting power.

“The suppliers of the aero-derivative fast-start units in the size range considered (40-50 MW each) are General Electric (‘GE’), PW Power Systems, and Siemens (formerly Rolls Royce). There are over 800 of the GE units in service including two (2) at Duke Energy Carolinas, LLC‘s W.S. Lee site in South Carolina and three (3) in Duke Energy Indiana, LLC. The GE fleet has over 8 million operating hours. With upgrades planned by Piedmont Natural Gas, on-site compression will not be required for the GE units.

“Over 500 PW Power Systems units have been placed in service. To provide the output required, this unit is assembled with two turbines driving a single generator.

“Fewer than 100 Siemens units are in service with a total fleet operating history of less than one million hours. The Siemens unit requires a higher gas pressure than can be provided by the existing Piedmont Natural Gas system at a reasonable cost. If the Siemens model turbines are selected, on-site gas compression would be required as a more cost-effective solution.

“The final selection process considered normalized capital cost in $/kW, performance (output and heat rate), experience, reliability, maintenance cost, and contract terms and conditions. Contract negotiations are currently underway with the top evaluated bidder.”

New units will able to use existing support facilities

Landseidel added: “The units will tie into the existing 115kV switch yard on site and take advantage of transmission capacity on the 115kV system without significant transmission upgrades. In addition to the utilization of the switch yard and transmission capacity, the site provides other cost advantages including reuse of the recent combined cycle project’s already cleared and leveled construction parking and laydown areas, existing fuel oil infrastructure, and existing natural gas infrastructure. There are also operating cost synergies associated with the adjacent combined cycle plant.

“As part of the Sutton Blackstart CT Project, new 115 kV transmission lines will be constructed from the high side of each generator step-up transformer. A single 115 kV transmission line of approximately 1500 feet in length will connect the Sutton Blackstart CT Project to the existing 115 kV Sutton switchyard at a breaker position previously used for the retired coal units. All of the additional transmission facilities will be located on existing Duke Energy Progress property at the Sutton Plant site.

“The Project will be dual fuel capable of burning pipeline natural gas or ultra-low sulfur diesel fuel from on-site storage facilities. Piedmont Natural Gas’ system capacity will be upgraded to serve the Project by compressor additions at an existing Piedmont compression facility. A new meter and regulation station (M&R Station) is planned to serve the Project at a location adjacent to the Project. Duke Energy Progress will enter into an interruptible transportation service agreement with Piedmont to provide gas transportation service for the Project.

“The plant gas supply will be served initially from Transco utilizing Duke Energy Carolinas existing gas transportation service agreements and supply portfolio. In the future, the proposed Atlantic Coast Pipeline (‘ACP’) will tie into Piedmont’s system in Robeson County and will be able to provide gas supply to the Sutton facility.

“The fuel oil unloading and storage facilities built for the combined cycle plant at Sutton will be used to also serve the new simple cycle facility. The onsite fuel oil storage can provide nearly two weeks of continuous full load operation for the new simple cycle units or three days of continuous full load operation for the combined cycle and simple cycle units.”

This project fits into the utility’s latest integrated resource plan

Glen A. Snider, employed by Duke Energy Carolinas as Director of Carolinas Resource Planning and Analytics, said in April 15 testimony that the Duke Energy Progress 2014 integrated resource plan (IRP) identifies the need for an additional 619 MW of new resources to meet customers’ energy needs by 2020 and 3,569 MW by 2029. As reflected in the 2014 IRP, Duke Energy Progress has determined that the Sutton Blackstart CT Project is needed in the 2017 timeframe to provide critical blackstart and fast-start capabilities, regional voltage support, as well as system capacity. The Duke Energy Progress 2014 IRP Short Term Action Plan includes the 84 MW Sutton Blackstart CT Project as the replacement for the existing 1960s vintage 61 MW Sutton CT Units 1, 2A and 2B.

Under the Base Case in the 2014 IRP, the portfolio consists of 602 MW (1,187 MW nameplate) of compliance and non-compliance renewable generation, 2,598 MW of new natural gas combined cycle capacity, 1,398 MW of new natural gas combustion turbine capacity (including the Sutton Blackstart CT Project), 34 MW of nuclear uprates capacity, 579 MW of Demand-Side Management (DSM), and 571 MW of Energy Efficiency (EE).

Snider wrote: “As reflected in the 2014 DEP IRP, over the last several years, aging, less efficient coal plants have been replaced with a combination of renewable energy, EE, DSM, and state-of-the-art natural gas generation facilities. In addition, the Company has retired 144 MW of old, inefficient CT units over the past three years and has identified an additional 794 MW of CT generation that will need replacement in the 2017-2027 timeframe, including the 1960s vintage obsolete Sutton CT units that will be retired and replaced as part of the Project.”

Snider added: “There are several quantitative and qualitative reasons Duke Energy Progress concluded that the Sutton Blackstart CT Project is the best resource addition for our customers’ benefit. An important function of the existing Sutton blackstart CT units is for transmission system restoration in the event of a blackout and to restore offsite power to the Brunswick Nuclear Plant necessary to achieve and maintain safe shutdown of both nuclear reactors in the event of a plant blackout. The Sutton Blackstart CT Project will have the capability to fulfill the blackstart function that the units to be retired have, in addition to providing the incremental reliability and functionality attendant with this new technology as compared to the 1960s vintage technology that is being replaced. For example, the Sutton Blackstart CT Project will also provide fast-start capability that the retiring units do not have, thereby providing additional resource capability for Duke Energy Progress to meet applicable North American Electric Reliability Corporation (‘NERC’) contingency reserve requirements. The Project will also provide voltage support in a critical area of the DEP transmission system.

“The Duke Energy Progress 2014 IRP projects that a total of approximately 1,078 MW (nameplate) of rated compliance and noncompliance renewable energy resources will be interconnected to the Company’s system by 2020, with that figure growing to approximately 1,187 MW (nameplate) by 2029. These resources help the Company comply with renewable energy mandates and provide important energy benefits to DEP’s customers; however, the inherent intermittency of these resources does not allow the capacity to be dispatched or contribute to reliability the same as a traditional resource such as a combustion turbine. Thus, the load following/fast-start capability of the Sutton Blackstart CT Project provides additional system flexibility to help accommodate the impacts resulting from the increasing amounts of intermittent resources being added to the Duke Energy Progress system.” 

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.