High-strength materials for power turbines

The DOE has selected two proposals from Texas A&M and the University of Pittsburgh to study ways to improve the materials in a key section of future power plants – the turbine.

High-strength materials will be one of the critical requirements for the high-tech power plants of the future, so the US Department of Energy will use the third and final round of its current ‘Vision 21’ competition to concentrate on two projects that will help improve the strength and durability of tomorrow’s metals.

Vision 21 is a US Energy Department research and development effort that looks to the day when energy plants – including those that use coal – would be practically emission free. In two competitions to date, the Department has selected a wide array of advanced technologies that ultimately would form the ‘building blocks’ for this ultra-clean futuristic power plant.

Now, the department has selected proposals from Texas A&M University, College Station, TX, and the University of Pittsburgh, Pittsburgh, PA, to study ways to improve the materials in a key section of the future plant – the turbine.

The two universities will focus on making the blades of Vision 21 turbines capable of withstanding the high operating temperatures needed to achieve the superior performance levels envisioned for these new plants.

Future Vision 21 plants will be designed to run on a variety of fuels – clean natural gas as well as fuels with more impurities, such as coal or possibly a combination of feedstocks such as biomass, municipal wastes, or petroleum coke.

To boost overall fuel-to-energy efficiencies, a Vision 21 plant would likely convert these fuels into gaseous form that would be fired in high-temperature, high-efficiency gas turbines. The blades must be made strong and durable enough to withstand the harsh, often corrosive effects of the hot gases. When impurities are present in the high-velocity gases, the technical challenge of protecting the turbine blades is even greater.

For their part, Texas A&M researchers will develop a model that describes the way single-crystal turbine blades respond to high temperatures. An especially important part of the project will be to observe how defects form at high temperatures and move through the structural lattices of the turbine blades.

The university researchers will be joined in the 3-year project by engineers from the New Jersey Institute of Technology, Newark, NJ, and GE Research, Niskayuna, NY. The Energy Department will provide nearly $354,000 of the project’s $443,000 total cost. The rest will come from the private sector participants.

While University of Pittsburgh researchers will work on improving the durability of turbine components with a goal of making them strong enough to withstand the effects of impurities that may be present in the high temperature gases. Pitt researchers will apply a dense overlay of aluminium oxide on the surface of turbine blades to create a corrosion-resistant coating.

The Energy Department’s share of the $504,000 project, also planned to run over three years, will be approximately $333,000, with the remainder contributed by the University and its research partners.