Duke plans new capacity at Suwannee, Hines plants

Duke Energy Florida on May 27 petitioned the Florida Public Service Commission for a determination that it has a need for additional generation capacity prior to 2018 and that its Suwannee Simple Cycle and Hines Chillers Power Uprate projects are the most cost-effective alternatives to meet that need.

The utility, which is a subsidiary of Duke Energy (NYSE: DUK), filed separately on May 27 with the PSC for approval of the 1,640-MW, gas-fired Citrus County combined-cycle project, to be built next to its Crystal River power plant and fully operating by the end of 2018.

The Suwannee Simple Cycle and the Hines Chillers Power Uprate projects are the most cost-effective options to fulfill DEF’s capacity and energy needs prior to 2018, the utility said.

The Suwannee project leverages use of existing land, gas, and transmission infrastructure at the company’s existing Suwannee power plant site and will have low air emissions using proven combustion turbine technology. In addition, the F class combustion turbine technology used for the Suwannee Simple Cycle project is well suited to peaking capacity needs with both fast-start capability and high reliability.

The Hines project meets the company’s need for reliable peaking capacity through an increase in the efficient power output of the existing natural-gas fired, combined cycle power plants located at the Hines Energy Complex (HEC), providing customers the savings associated with achieving reliable summer peaking capacity at combined-cycle generation efficiency without having to build additional peaking capacity at another site on DEF’s system.

The company currently has a total summer net generation capacity resource of 11,275 MW. This generation capacity resource includes utility purchased power (413 MW), non-utility purchased power (1,704 MW), combustion turbine (2,471 MW), fossil steam (3,410 MW), and combined cycle plants (3,277 MW).

Suwannee to get two new F Class turbines to replace existing capacity

The Suwannee Simple Cycle project involves two dual-fuel F class combustion turbine generators that will be purchased and installed together with two generator step-up transformers to generate an estimated 320 MW. The project will also include fuel oil and demineralized water storage tanks, and related balance of plant facilities.

The Suwannee site has existing combustion turbines fired by gas and oil and existing steam units with supporting pipeline and transmission infrastructure.

One of the F class combustion turbines will be connected to the existing 115-kV transmission switchyard and the other F class turbine will be connected to the existing 230-kV transmission switchyard. Limited transmission network upgrades estimated at $15.7m are needed to reliably integrate the additional generation to the electric grid.

Natural gas will be supplied to the two F class combustion turbines by the Florida Gas Transmission (FGT) pipeline and a local gas lateral to the existing site metering and regulating station on site.

The existing Suwannee steam units will be retired, thus modernizing the fleet and reducing the site environmental impacts.

The Suwannee Simple Cycle Project is expected to have an average summer full load heat rate and operate at a capacity factor range consistent with its peaking generation capacity role on DEF’s system. The plant will have low air emissions using proven dry, low NOx combustors with water injection when operating on fuel oil.

DEF estimates that it will cost about $197m, including the Allowance for Funds Used During Construction (AFUDC), to build the Suwannee Simple Cycle project. This estimate includes: the cost to purchase the combustion turbine generators and step-up transformers, along with other equipment for the project; the engineering, procurement, and construction contract costs to build the project; owner costs; and the transmission switchyard and transmission network upgrades to connect the project to the grid.

The Suwannee Simple Cycle project is scheduled for commercial operation in June 2016.

Chillers to provide frigid boost to Hines capacity

The Hines Chillers Power Uprate project involves the installation of a chiller system on all four existing natural-gas fired, combined-cycle power blocks, Hines Units 1-4, located at the Hines plant in Polk County. Hines Units 1-4 are four 2×1 F class combined-cycle power blocks with a total installed capacity of about 1,900 MW. The chillers project will increase the summer capacity by approximately 220 MW.

The Hines Chillers Power Uprate project consists of chiller modules for the existing power block units, a large chilled water storage tank, an auxiliary power system, pumps and chilled water supply and return piping, and gas turbine air inlet chiller coils. The project will also involve modifications of the existing air inlet ducts on the power block units. The chiller system is designed to cool the gas turbine inlet air, which significantly increases the combined-cycle plant summer capacity while maintaining combined-cycle fuel efficiency.

The Hines Chillers Power Uprate project meets the company’s need for reliable capacity by the summer of 2017, the utility noted.

“Existing generation and site infrastructure will support this power uprate,” the utility wrote. “As a result, DEF is able to achieve an increase of approximately 220 MW in its summer capacity by utilizing an existing site and power block, saving customers the increased costs and time of building new generation at another existing site or a Greenfield site to achieve the same reliable summer capacity. The project will provide additional combined cycle summer capacity and fuel efficiency saving customers fuel costs.”

The estimated cost of the project is $160m.

Retirement of existing capacity helps drive this need

A major driver in the company’s need for additional generation is the retirement of capacity. In February 2013, the company decided to retire its Crystal River Unit 3 nuclear plant (CR3). CR3 accounted for approximately 790 MW of summer capacity. The company’s plan for compliance with the U.S. Environmental Protection Agency’s Mercury and Air Toxics Standards (MATS) at Crystal River Unit 1 (CR1) and Crystal River Unit 2 (CR2), which involves the use of new low-sulfur coal, will result in a reduction in their capacity of about 130 MW beginning in the spring of 2016, with the units to be retired around 2018, when the new Citrus County plant goes on-line.

The company also plans to retire some of its oldest combustion turbines in its fleet and its three 1950s vintage oil- and gas-fired steam generation plants at the Suwannee power plant site in 2016. These retirements account for 261 MW of summer generation capacity.

The company’s need now is approximately 280 MW of summer generation capacity commencing in 2016 that increases to 470 MW in the summer of 2017. DEF selected the Suwannee Simple Cycle and Hines Chillers Power Uprate projects to meet this need.

DEF said it needs the Suwannee Simple Cycle and Hines Chillers Power Uprate projects in the summer of 2016 and 2017, respectively, to meet its 20% reserve margin commitment. With the installation of the Suwannee Simple Cycle Project in 2016 and the Hines Chillers Power Uprate Project in 2017, the company’s reserve margin will be 20.4% in the summer of 2016 and 20.7% in the summer of 2017, respectively. Without these generation capacity additions, DEF’s reserve margin will decrease to 16.9% in the summer of 2016 and to 14.9% by the summer of 2017.

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.