Lessons for Policy, Industry and Science
Edited by Martin Junginger, Wilfried van Sark and André Faaij
Ric Hoefnagels, Anna Bergek and Paul Lako INTRODUCTION 11.1 The gas-fired Combined Cycle Gas Turbine (CCGT)1 plant is a combination of a gas turbine, a steam turbine and a Heat Recovery Steam Generator (HRSG), which makes use of the exhaust gas latent heat from the gas turbine to raise steam for the steam turbine. The first Combined Cycle plants were constructed in the late 1960s (Bergek et al., 2008). Before this time, gas-fired power plants were based solely on either steam (Rankine) cycles or gas turbines (Brayton cycle). Apart from Combined Cycle plants, gas turbine technology is still used in single cycle mode, predominantly for peaking plants. Other applications include Combined Heat and Power (CHP), re-powering projects and Integrated Gasification Combined Cycle (IGCC). With ~450 GWe of cumulative experience in 2004 (Figure 11.1), CCGT is considered a mature technology. CCGT technology has several advantages over coal-fired power or nuclear power plants. These include (Claeson Colpier and Cornland, 2002): ● ● ● ● ● ● ● ● High thermal efficiency, currently up to 60 per cent; Low emissions of NOx, SO2, etc.; Relatively low specific investment costs; Short construction schedule (generally three years); Low space requirement compared to, for example, nuclear or coalfired power plants; Relatively moderate capacities, up to 480 MW; Fast start-up capability of the gas turbine; the time needed for a cold start-up of the CCGT plant is about three hours, with a ‘ramp rate’ of 7 per cent / minute (NPPC, 2002); Economically attractive over (coal-based) fluidized bed boiler technology (Watson, 2004). 139 140...
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