Coal Age

MAR 2017

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16 March 2017 coal-fired power continued erations. Thus, power and fuel stock com- panies in coal-rich countries have sent emissaries to the plant to learn its secrets. "There's been a lot of interest from other users, scientists, academia and around the world," Mark Hornick, director of en- gineering and project management for TECO, said. "We've hosted groups from every continent, excluding Antarctica." Polk 1 is now the eldest IGCC facility in the world. Surrounded by natural gas- fired turbines, it stands as a testament to a previous era. Polk Remembers Built on reclaimed oak and slash pine bar- rens, Polk 1 started out as a gleam in the eye of the federal government. Dubbed the Tampa Clean Coal Technology Project, it "was selected by the U.S. Department of Energy (DOE) in December of 1989 as a Round III Demonstration Project for the Clean Coal Technology (CCT) Program," the NETL reported. "Construction began in October of 1994, followed by operation- al startup in September of 1996." For four years it was a demonstration. Coal was supplied by truck from TECO's transload- ing facility in Apollo Beach. The NETL provided operational spec- ifications. "The plant uses General Elec- tric Energy's (formerly owned by Texaco) commercially available, entrained-flow, oxygen-blown gasifier to produce syngas from coal, which feeds a combined-cycle turbine system to produce electricity. Each day, 2,200 tons of coal are first ground, combined with recycled and makeup pro- cess water to form a slurry, then partially oxidized in the gasifiers with 95% pure ox- ygen supplied by an air separation unit," the NETL reported. "The gasifier produces a high temperature and pressure, medi- um-British thermal unit (Btu) synthesis gas, which has a heat content of 267 Btu per standard cubic foot. Most — 95% — of the carbon contained in the coal is converted on a mass basis. Molten ash collects in the bottom of the gasifier before solidifying in a water-filled sump. The non-leaching slag is sold for use as construction material." All-in costs for launch and presumably the demonstration hit $303 million, the NETL reported, with $152 million coming from TECO and $151 million coming from the DOE. The NETL summarizes the early failures and snafus, clogs and corrosion, that caused outages or mandated repairs and represented unforeseen expenses. In 2000, TECO released an executive report to the government, summarizing the history of operations, compiling lessons learned, and providing predictions for the plant and the technology. It stated, "O&M costs have been much higher than expected. Sever- al expensive capital improvements have been required, and more renovation is in progress and planned. Fortunately, there have been no station reliability impacts." And reliable is now a term oft-used to describe Polk 1, Hornick said. The growing pains of the late 1990s are history. "Polk 1 is an integral part of our power-generation fleet," he said. "It is very competitive." It has an operating heat rate of 9,650 Btu per kilowatt-hour, "which is better than most conventional coal-fired plants," the NETL reported. Having "put the nail in the coffin" of the challenges accompanying the demo, the plant now runs "as we would expect it to run. Our overall average onstream factor has been 78% and we've had years as high as 82%," Hornick said. "It produced 27 mil- lion MW-hours through to the end of 2016. It has more cumulative generation than any other facility in the world." In 2000, TECO started adding natural gas-fired units to the facility. Eventually, the IGCC unit was accompanied by four natural gas units. In 2006, Polk 1 celebrat- ed its 10 th anniversary. By then established and reliable, it was "typically one of the lowest cost units in our system in terms of incremental costs," Hornick said "So it dis- patches very early in our fleet." Which begs the question why the natural gas units? Hornick said due consideration of a number of factors ensured Polk 1 was for a time an only child. "We look at the whole range of costs over the life cycle of the facility," he said. "You have to use fuel price forecasts for coal and natural gas." Perhaps equally importantly, construct- ing a syngas plant is almost prohibitively expensive, a recurring reality illustrated by Polk's sister plants. "We did look at build- ing one similar to Duke Edwardsport back in the mid-2000s," Hornick said. "We actu- ally changed our mind when we saw that the capital costs were getting higher. We decided to do a natural gas unit instead." All-in launch and demo costs were summarized in TECO's 2000 report. "The direct cost for a new single train 250-MW IGCC plant on the Polk site in Polk's cur- rent configuration incorporating all the lessons learned would be about $1,650/ kW." The report added that fully imple- menting the lessons learned could shear off 20%. However, Hornick said, those numbers would now need to be adjusted for inflation, if not for the lessons gleaned in the 16 years since. Nonetheless, both the NETL and TECO describe Polk 1, and IGCC in general, as Duke Energy's Edwardsport IGCC Project, above, with two gasifiers and engineered for eventual carbon capture for EOR, replaced a 160-MW pulverized coal-fired plant and came online in 2013. (Photo: Duke Energy)

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