Turbine blades are currently made of single crystal nickel (Ni)- or cobalt (Co)-based superalloys. After many years of refinements, their development has plateaued. Researchers are hence trying to leverage and integrate recent advances in alloy design and modeling, refractory alloys, advanced manufacturing technologies, and high-throughput testing to realize significant improvements in the operational capability of gas turbines.
Turning up the heat
The temperature capability of current state-of-the-art blade materials has improved steadily over the last few decades to 1100 ºC, through incremental microstructure and chemistry refinement.
The ULTIMATE program targets enabling gas-turbines blades to operate continuously at 1300 ºC in a material test environment—or with coatings, with turbine inlet temperatures of 1800 ºC or higher. ULTIMATE stands for Ultrahigh Temperature Impervious Materials Advancing Turbine Efficiency, and is part of the ARPA-E program series.
The use of novel materials can boost temperature and potentially increase gas turbine efficiency up to 7%, improving power plant economics. By 2050, such a 7% efficiency improvement in gas turbines used for U.S. electricity generation could save up to 15-16 quads of energy, researchers said. For aircraft turbines the energy savings could be 3-4 quads.
Research will be conducted in two phase, covering proposed for a maximum of 18 and 24 months. In phase I, project teams will demonstrate proof of concept of their alloy compositions, coatings, and manufacturing processes through modeling and laboratory scale tensile coupon (sample) testing of basic properties. In phase II, approved project teams will investigate selected alloy compositions and coatings to evaluate a comprehensive suite of physical, chemical, and mechanical properties as well as produce generic small-scale turbine blades to demonstrate manufacturability.
Propping up manufactures
Natural gas turbines currently produce an estimated 35% of the electricity generated across the United States. The DOE research grant can help turbine developers to trial and commercialize new turbine coatings to enhance their sales in the current difficult economic environment.
According to ARPA-E Director Lane Genatowski, the novel ultrahigh-temperature alloys in conjunction with coatings are meant to boost efficiency of gas turbines, used both for power generation and aviation.
“Developing new, innovative technologies under the ULTIMATE program will allow us to better utilize gas turbines across multiple power sectors, from electricity generation to transportation and aviation,” said DOE Undersecretary of Energy Mark W. Menezes. In the long-run, the DOE-aided research is mean to help “making all of these industries more efficient,” he concluded.