| Project Detail |
Gas turbines produce approximately 35% of the total electricity generation in the U.S. Improving their efficiency is important for reducing energy usage and carbon emissions. Similarly, higher efficiency aviation and other industrial turbines would improve the economics and reduce greenhouse gas emissions in these sectors. Gas turbine efficiency largely depends on the gas temperature at the inlet; the higher the temperature, the higher the efficiency. Gas turbine operational temperature is currently limited by its component materials, particularly those in the path of the hot gas such as turbine blades, vanes, nozzles, and shrouds. Turbine blades experience the greatest operational burden because they must concurrently withstand the highest temperatures and stresses. Currently, turbine blades are made of single crystal nickel (Ni)- or cobalt (Co)-based superalloys. After many years of refinements, their development has plateaued. There is a need to discover, develop, and implement novel materials that work at temperatures significantly higher than that of the Ni or Co superalloys if further efficiency gains are to be realized.
Project Innovation + Advantages:
Current Ni-based alloys used in turbine blade applications are operating at 1100°C, which is approximately 90% of their melting temperatures. Refractory alloys, such as niobium (Nb) alloys, can withstand higher temperatures. Oak Ridge National Laboratory (ORNL) will use computational modeling tools and advanced characterization to develop two classes of Nb alloys for use in a tri-layered turbine system consisting of a core high strength Nb-alloy layer, an intermediate layer consisting of a more oxidation resistant Nb alloy compatible with a core layer, and an external thermal barrier/coating such as a commercially available silicide coating designed to provide oxidation resistance. The alloys will be able to continuously operate at 1300°C with coatings. This capability will enable gas turbine inlets of 1800°C or higher.
Potential Impact:
Combining development of new ultrahigh temperature materials with compatible coatings and manufacturing technologies has the potential to increase gas turbine efficiency up to 7%, which will significantly reduce wasted energy and carbon emissions. |
