For years, gas turbine manufacturers faced a barrier that, for all practical purposes, capped power generating efficiencies for turbine-based power generating systems.
The barrier was temperature. Above 2300 degrees F, available cooling technologies were insufficient to protect the turbine blades and other internal components from heat degradation. Since higher temperatures are the key to higher efficiencies, this effectively limited the generating efficiency at which a turbine power plant could convert the energy in the fuel into electricity.
The Department of Energy's Office of Fossil Energy took on the challenge of turbine temperatures in 1992, and nine years later, its private sector partners produced "breakthrough" turbine systems that pushed firing temperatures to 2,600 degrees F and permitted combined cycle efficiencies that surpassed the 60 percent mark - setting the current world record for turbine efficiency.
Moreover, the advanced turbines achieved the higher firing temperatures while reducing the amount of nitrogen oxides formed to less than 10 parts per million (NOx is a product of high temperature combustion), without any post-combustion cleanup.
Among the innovations that emerged from the Department's Advanced Turbine Systems program were single-crystal turbine blades and thermal barrier coatings (TBC) that could withstand the high inlet temperatures, along with new firing techniques to stabilize combustion and minimize nitrogen oxide formation.
The GE H System Turbine
On February 18, 2000, GE Power Systems unveiled the first gas turbine slated for the U.S. market that would break through the temperature barrier and push efficiencies to unprecedented levels. Using advanced materials and revolutionary new steam-cooling technology, the new turbine is capable of operating at 2600 degrees F.
The H System is GE's most efficient gas turbine combined cycle product and is the first platform designed with the capability to reach 60 percent thermal efficiency. The H System's higher fuel efficiency provides power producers and end users lower cost of electricity through fuel conservation while adhering to strict environmental requirements for natural gas fired power plants. The revolutionary H System was funded in part through the U.S. Department of Energy's Advanced Turbine System Program.
The innovative, closed-loop steam cooling system and advanced coating materials are key technology enablers to achieving the higher firing temperatures required for its increased efficiency. Higher efficiency also translates into improved environmental performance. For every unit of electricity produced, the H System uses less fuel and produces fewer greenhouse gases and other emissions when compared to other large gas turbine combined-cycle systems.
Baglan Bay Power Station in Cardiff, Wales, U.K., is the site of the world's first installation of H technology. The plant is capable of producing 480 megawatts of electricity, enough to meet the needs of half a million households. It is supplying power to the Baglan Energy Park, with the remaining electricity going to the U.K. national grid.
Siemens Westinghouse W501G Advanced Gas Turbine
The partnership between the Department of Energy and Siemens Westinghouse, under the Advanced Turbine Program, has resulted in a suite of advanced gas turbine technologies that today are operating in over 165 gas turbines in North America and helping them to be more efficient, more environmentally friendly, and more reliable.
The suite of technologies that have been developed and commercialized under the program include the following:
- High Efficiency Compressor
- Advanced Low NOx Combustion Technology
- First Application of Closed Loop Steam Cooling in an Industrial Gas Turbine
- Advanced Turbine Blade and Vane Materials
- High Temperature TBC and Abradable Coatings
- Advanced Row 4 Turbine Blades
- 3-D Aero Technology
- Advanced Brush Seals