VIsiting the nation's first greenfield commercial IGCC power plant

POWER-GEN International 2010 got off to a quick start Monday morning when I, along with 45 other show and conference attendees, had the opportunity to tour the 260 MW Polk Power Station, the nation's first greenfield integrated coal gasification combined-cycle (IGCC) power plant.

The Tampa Electric Co.-owned Polk Power Station was constructed on a 4,300- acre piece of land that was once used for phosphate mines. The IGCC plant, referred to as Unit 1, is a first-of-its-kind combination of two technologies, coal gasification and combined-cycle, that began commercial operations in 1996.

Oxygen-blown gasification, a technology originally developed by Texaco and then purchased by General Electric, combines coal that is stored on-site in two 5,000 tons silos at the Polk plant with oxygen in the 40-foot-tall GE gasifier to produce the fuel syngas. After processing, the clean coal gas is used in the GE 7FA combustion turbine to produce electricity.

To generate even more power at the same plant, the combined-cycle design takes the "waste" exhaust heat from the 7F turbine, recovers it in the HRSG to produce high-pressure steam that then passes through GE D11 steam turbine. When firing with syngas, the IGCC heat rate at Polk is about 9,300 Btu/kWh.

Vernon Shorter, a consultant for TECO who led the plant tour, said power providers “should consider this technology because of the environmental benefits and efficiency.”

Built with $140 million of support from the U.S. Department of Energy as part of its Clean Coal Technology program, the Polk station operates at 90 percent availability with over 98 percent SO2 reduction, and 90 percent NOX control. The plant is also considered zero process water discharge, which DOE recognized as among the world’s cleanest. The combined-cycle technology requires less cooling water than conventional technology and TECO was able to modify the existing mine cuts to act as the plant’s cooling reservoir. And in March 2009, TECO established an agreement with the City of Lakeland and the Southwest Florida Water Management District to supply Polk Power Station with up to five million gallons of treated reclaimed water daily that would otherwise be discharged into Tampa Bay.

For TECO to meet summer demand, the Polk station has four additional simple cycle GE 7FA combustion turbines on site that were brought online between 2000 and 2007. Unit 2 and Unit 3 are 180 MW duel fuel turbines that are fired with natural gas and distillate oil, while the 160 MW Units 4 and 5 operate using only natural gas.

The Polk IGCC station has operated on over 20 different fuels, including coals, coal blends, coal/petroleum coke blends and coal/coke/biomass blends.

“This plant has produced more megawatts than any other IGCC plant in the world,” said Shorter.

Although the plant was not in operation the day we toured it due to a problem with the sulfur removal plant, an occurrence that is rare, added Shorter, the tour was informational. It was my first tour of an IGCC facility, along with many of the other visitors, and I recommend visiting the facility if the opportunity ever becomes available.