Duke Energy nears air permit for Hines ‘chiller’ project

The Florida Department of Environmental Protection on Dec. 12 put out for comment a draft air permit covering a “chiller” project that will add generating capacity in Florida’s hot summer conditions at the Hines Energy Complex of Duke Energy Florida.

This Duke Energy (NYSE: DUK) subsidiary was approved this past fall by the Florida Public Service Commission for both the Hines chiller project and the construction of the new, 1,640-MW Citrus combined cycle facility. Incidentally, the DEP on Dec. 16 issued the final air construction permit for the Citrus project.

Duke Energy Florida (DEF) operates the Hines Energy Complex, which is located on an approximate 8,000-acre site in southwest Polk County that was previously a phosphate mine. 

  • Power Block 1 consists of a “two-on-one” combined cycle unit with a nominal capacity of 500 MW; a 99 million Btu per hour (MMBtu/hour) auxiliary boiler; and a 97,570 barrel fuel oil storage tank.
  • Power Blocks 2, 3 and 4 are also “two-on-one” combined cycle units, each with a nominal capacity of 530 MW. Emissions from each combustion turbine (CT) and heat recovery steam generator (HRSG) combination are vented through a single stack. 

Each “two-on-one” power block includes two combustion turbine-electrical generators (CTGs), two heat recovery steam generators and one steam turbine-electric generator (STG).

Chiller systems can cool the inlet air, thus increasing its density and energy production at the given ambient temperature. The cooling is accomplished by drawing CTG inlet air across cooling coils, in which chilled water is circulated. The additional power at a given ambient temperature does not change the maximum power that is possible at a given compressor inlet temperature, the DEP noted. The net effect is to increase power production during the middle of summer (or whenever the ambient temperature is high).

Duke Energy Florida will install water-cooled inlet air chillers on all eight CTGs to decrease the compressor inlet temperature during high ambient temperature days. The method primarily uses less-expensive off-peak power at night to generate the chilled water for inlet air cooling during peak demand periods during the day. The four blocks of chillers will come into service in alignment with future plant outages. All systems will be in service by the summer of 2017. According to the Florida PSC approval, the project will add 220 MW of summer capacity and cost of about $160m.

The current plan is to install a single three-cell cooling tower to service all the chillers. The total maximum makeup flow rate for the cooling tower is projected to be 1,216 gallons per minute (gpm) and the maximum cooling tower recirculation flow rate is projected to be 44,000 gpm.  

“In 2013 DEF completed the conversion of the nominal 1,100 MW Anclote Power Plant (conventional steam units) to exclusive natural gas service,” the DEP wrote. “According to discussions with company representatives, reductions in future emissions from Hines are related to changes in the operating dispatch order, particularly following the construction of the Citrus Combined-Cycle Plant and the increases natural gas prices that are projected for the future. DEF System-wide combined cycle natural gas supply and use will significantly increase by 2019-2020 when the nominal 1,640 MW Citrus Combined Cycle Project displaces production from two conventional coal-fueled units at the DEF Crystal River Energy Complex.”

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.