CCGT

CCGT stands for Combined Cycle Gas Turbine, a method of electricity generation that improves the efficiency of a gas-fired plant by using two thermodynamic cycles in sequence. In a typical CCGT plant, natural gas is burned in a gas turbine, whose hot exhaust gases are directed to a heat recovery steam generator (HRSG). The steam produced by the HRSG then drives a steam turbine, generating additional electricity from the same fuel source. The combination yields higher overall efficiency than a simple cycle gas turbine.

Layout and configuration: most plants employ one or more gas turbines with one or more HRSGs feeding one or more steam turbines; arrangements may be single-shaft or multi-shaft. Duct firing or supplemental firing can boost steam production and output. Plants are often designed to operate in a flexible load range, from partial to full capacity, to support grid reliability.

Performance: overall plant efficiencies commonly range around 50-60% (net, LHV basis), with modern high-efficiency units achieving somewhat higher under optimal conditions. CCGTs are known for fast start-up and flexible ramping, making them well suited to balancing intermittent renewable energy sources and providing mid-merit or baseload support in many grids.

Environmental and fuel considerations: the principal fuel is natural gas, which emits less CO2 per megawatt-hour than coal. Emissions of NOx are controlled with selective catalytic reduction or other measures. The technology can be adapted to other gaseous fuels and, in development, to hydrogen blending or biogas.

Global usage and economics: CCGT plants are widely deployed worldwide for new generation due to efficiency and flexibility, with capacities ranging from several hundred megawatts to over a gigawatt per site. Capital costs are offset by lower fuel use and operational flexibility.