US DOE targets 65% CCGT efficiency and super- critical CO2 in advanced turbine funding awards

The US Department of Energy has selected 14 advanced technology research & development projects to receive a total of approximately $7 million in federal funding under a funding opportunity aimed at developing advanced components for 65% combined cycle efficiency, supercritical carbon dioxide (sCO2) power cycles and advanced modular heat engines (DE-FOA-0001816).

According to the DOE, the cost-shared research and development projects “will support the goals of The Office of Fossil Energy’s Advanced Energy Systems Program by developing advanced, highly efficient, turbine-based technologies for coal-derived synthesis gas, coal-derived hydrogen, and natural gas.” The National Energy Technology Laboratory (NETL) will manage the projects. DOE summarises the selected projects as follows:

Area of interest 1: advanced combustion turbines for combined cycle applications

• High-temperature additive architectures for 65% efficiency – General Electric (Schenectady, NY) will develop advanced turbine technologies for hot-gas-path inlet components. Enabled by advanced manufacturing, these technologies will result in efficiency improvements. This project will develop novel and innovative component airfoil and end-wall architectures that provide cooling-flow savings while maintaining component durability. (DOE funding: $499 690; non-DOE funding: $232 994; total value: $732 684)
• High-temperature, high AN2 last stage blade for 65% combined cycle efficiency – General Electric (Schenectady, NY) will cultivate a last-stage blade technology by developing rotor system designs and vibration-management strategies. This technology will be necessary to realise the goal of 65% combined cycle efficiency and reduced cost of electricity. Knowledge gained from this project will open design space to move beyond today’s state of the art. (DOE funding: $499 989; non-DOE funding: $241 835; total value: $741 824) 
• Turbine aero-thermal technologies for 65% combined cycle efficiency – General Electric (Schenectady, NY) will create a gas turbine technology development programme that develops mechanically feasible, emerging, aerodynamic, and heat-transfer technologies to optimise the entire turbine system and improve overall gas turbine cycle efficiency. General Electric will select conceptual design configurations that contribute to the 65% efficiency performance goal. (DOE funding: $499 614; non-DOE funding: $238 369; total value: $737 983)
• Additive manufactured metallic-3D Ox-Ox CMC integrated structures for 65% combined cycle efficient gas turbine components – Siemens Energy (Orlando, FL) will develop a metallic additive manufacturing (AM) and 3D oxide-oxide ceramic matrix composites (3D Ox-Ox CMC) based design for advanced vanes. The design will eliminate the need for film cooling and significantly reduce overall cooling requirements. The use of AM-3D Ox-Ox CMC components in all relevant hot turbine stages can reduce total cooling and leakage flow of turbine components by at least 50%. This reduction translates to an increase of approximately 1.5% in combined cycle efficiency. (DOE funding: $494 394; non-DOE funding: $123 599; total value: $617 993)
• Design and development of low-weight, titanium aluminide airfoils for high-performance industrial gas turbines meeting 65% combined cycle efficiency – Siemens Energy (Orlando, FL) will create a prototype titanium aluminide (TiAl) turbine blade design capable of operating in a baseline gas turbine application. This blade will increase the exit annulus area of large frame gas turbines and support the target combined cycle efficiency levels of 65%. The project will establish an understanding of a state-of-the-art cast TiAl alloy, capable of withstanding high temperatures. (DOE funding: $492 183; non-DOE funding: $123 046; total value: $615 229)
• Extension of operating envelope for an extremely low NOx axial stage combustion system – Siemens Energy (Orlando, FL) will develop an optimised design for an advanced high-temperature combustor for gas turbine applications. Proof-of-concept testing on a combination of advanced transition design and distributed combustion system showed significant advantages in terms of NOx emissions. The goal is to maximise the firing temperature while maintaining stable operation within the NOx emission limits so that future commercial power systems can realistically target combined cycle efficiencies of 65% or greater while achieving low NOx emissions. (DOE funding: $499 943; non-DOE funding: $124 986; total value: $624 929)
• Hybrid Ceramic-CMC vane with EBC for future coal-derived syngas-fired highly efficient turbine combined cycle – United Technologies Research Center (East Hartford, CT) will lead the conceptual design of high-pressure turbine vanes that use a novel combination of monolithic ceramics and ceramic matrix composites to increase component efficiencies within the turbine hot section and provide key building blocks for a 65% efficient system. (DOE funding: $499 974; non-DOE funding: $124 994; total value: $624 968)

Area of interest 2: development of oxy-fuel combustion turbines with CO2 dilution for sCO2-based power cycles

• Development of oxy-fuel combustion turbines with CO2 dilution for sCO2-based power cycles – Southwest Research Institute (San Antonio, TX) will develop a conceptual design for a sCO2, coal syngas, or natural gas-fired oxy-fuel turbine, leading to high cycle efficiencies, smaller footprints, reduced cost, and more power output with the potential for use with various energy sources, including fossil energy. This project assesses the development of a thermodynamic cycle with natural gas as the fuel and a sCO2 turbine, including the development of a nominal engine component; conceptual development of an oxy-fuel sCO2 combustion turbine; thermal management options and concepts; and material selection for the hot sections of the cycle. (DOE funding: $499 693; non-DOE funding: $126 922; total value: $626 615)

Area of interest 3: turbine-based modular hybrid heat engines for fossil energy applications

• Turbo-compound reheat gas turbine combined cycle – Bechtel National (Reston, VA) will develop its turbo-compound reheat gas turbine combined cycle for small-scale demonstration. The system is modular, scalable, fuel-flexible, highly efficient, and amenable to distributed generation and cogeneration. This cycle is based on a combination of technologies to enable thermodynamic cycle performance, including constant volume combustion, reheat, and waste recovery. (DOE funding: $499 823; non-DOE funding: $124 956; total value: $624 779)
• Integrated optimisation and control of a hybrid gas turbine/sCO2 power system – Echogen Power Systems (Akron, OH) will define a hybrid gas turbine sCO2 power cycle design to achieve improved steady-state and transient performance relative to a baseline gas turbine/sCO2 combined cycle plant. The cycle optimisation code will be extended to include the gas turbine system. With this approach, an integrated optimisation process can be used to obtain higher thermodynamic efficiency for the overall plant. The commercial embodiment of this system could benefit microgrid and remote power installations by improving their efficiency and load-following characteristics. (DOE funding: $500 000; non-DOE funding: $125 000; total value: $625 000)
• Advanced modular sub-atmospheric hybrid heat engine – Gas Technology Institute (GTI) (Des Plaines, IL) will develop a turbine- based advanced modular sub-atmospheric hybrid heat engine for fossil energy applications. The engine will be developed as a modular unit that can be used with modular coal or biomass gasifiers, distributed power generation systems, large power plants composed of multiple generating units, and with natural gas compression stations. This hybrid heat engine can achieve greater than 65% net electrical or mechanical power-conversion efficiency based on lower heating value of the fuel and provide ultra-low pollutant emissions at a competitive cost. (DOE funding: $499 997; non-DOE funding: $127 230; total value: $627 227
• A modular heat engine for the direct conversion of natural gas to hydrogen and power using hydrogen turbines – Gas Technology Institute (Des Plaines, IL) will design, test, and demonstrate a modular heat engine system for clean and efficient conversion of natural gas to power, hydrogen, and carbon dioxide. The concept centres on clean power generation using hydrogen produced from GTI’s compact hydrogen generator (CHG), combined with an existing gas turbine modified for hydrogen combustion or with an advanced hydrogen turbine. Using the CHG technology, GTI predicts a greater than 15% reduction in hydrogen cost. (DOE funding: $500 000; non- DOE funding: $125 000; total value: $625 000)
• Novel modular heat engines with sCO2 bottoming cycle utilising advanced oil-free turbomachinery – General Electric (Niskayuna, NY) will evaluate a highly-efficient heat engine for natural gas pipeline compression. The project is centred on the conceptual design of a novel, hermetically sealed oil-free sCO2 bottoming cycle for a natural gas combustion turbine used for pipeline compression. The successful implementation of a sCO2 bottoming cycle can save 41.8 billion cubic feet of natural gas annually, equating to approximately $120 million in annual fuel cost savings and a 2.5-million-ton annual reduction in CO2 emissions. (DOE funding: $499 795; non-DOE funding: $125 000; total value: $624 795)
• Advanced gas turbine and sCO2 combined cycle power system – Southwest Research Institute (San Antonio, TX) will create a modular, highly-efficient combined cycle power system that will offer reduced operating costs and footprint, cleaner and more fuel- efficient operation, and enhanced load-following capability. The technology couples a supercritical-CO2-based waste-heat recovery system (WHRS) to the discharge of an existing gas turbine package. The sCO2 WHRS technology is believed to increase the efficiency and environmental performance of existing gas turbine installations, including natural gas compression stations. (DOE funding: $500 000; non-DOE funding: $125 000; total value: $625 000)