Combustion (gas) turbines are key components of advanced systems designed for new electric power plants in the United States. With gas turbines, power plants will supply clean, increasingly fuel-efficient, and relatively low-cost energy.
Advanced turbine based cycles like Supercritical CO2-based power cycles have shown the potential for increased heat-to-electricity conversion efficiencies, high power density, and simplicity of operation compared to existing steam-based power cycles. The sCO2 power cycle utilizes small turbomachinery, is fuel- and/or heat-source neutral, and efficient.
The U.S. DOE continues its efforts to push the limits of turbine performance in response to the nation’s increasing power supply challenges by focusing on the underlying factors affecting combustion, aerodynamics/heat transfer, and materials for advanced turbines and turbine based power cycles. Temperature continues to be the barrier for increasing turbine efficiency. Research being pursued by the program will enable turbines to operate in excess of 3100°F, with low NOx emissions, increased power output, and efficiencies over 65%. Some of the technologies that will enable this transformational jump in capabilities include ceramic matrix composites (CMCs) for airfoils and combustion components, advanced low-NOx micro-mixer combustion system that can efficiently fire multiple fuels at different loads while keeping emissions low, and pressure gain combustion. Pressure gain combustion is an alternate form of combustion that increases pressure through the combustor compared to standard combustion techniques that result in a pressure loss. Integrating this technology into a combustion turbine could provide further performance increases.
Supercritical CO2 power cycles using advanced turbomachinery could offer efficiency and performance improvements for some fossil energy cycles. The turbines for these cycles are unique in that they will have high power density, lower peripheral speeds, high blade loading, and high shaft speeds, all of which will factor into the final turbine designs. The high pressure, relatively high temperature, uncertainty of the CO2 state near the critical point, and high power density create design challenges for the supercritical CO2 turbomachinery.