With fossil fuels projected to remain the dominant source of energy for decades to come, advanced combustion turbine technology will play a critical role in capitalizing on the nation’s vast domestic resources, and the National Energy Technology Lab (NETL) is working on ways to improve that technology.
NETL said its work to improve advanced combustion turbines seeks to boost overall turbine efficiency, cut the cost of electricity, reduce pollutant emissions and enable more affordable carbon capture options.
NETL’s turbine program focuses on developing advanced components for the next-generation of combustion turbines. By working to improve components, rather than complete turbines, the benefits are realized in a shorter time frame through industry partnerships, it said. The lab’s advances in turbine research can be easily applied to existing and future product lines, leveraging existing equipment and products for component demonstration. Pushing components out to the current fleet during maintenance operations continually boosts efficiency for power customers, without delays for a complete market-ready product.
NETL’s efforts to improve advanced combustion turbines are focused on boosting efficiency beyond 65% for combined-cycle systems using natural gas, which equates to about 60% efficiency for combined-cycle systems using coal. Greater temperatures — around 3,100 degrees Fahrenheit as air enters the turbine — are the key to achieving those efficiencies, the NETL said. However, higher heat introduces new challenges: material limitations, cooling measures, potential for gas leakage, rising manufacturing costs, and increased emissions.
NETL is working with a variety of external partners to improve turbine components by addressing these issues through research and development (R&D) of key technologies, including the following:
• Ceramic matrix composite (CMC) components. Ceramic-based composite materials offer added strength and heat resistance amid the turbine’s harsh temperatures. Turbine components made from these materials curb cooling requirements and increase efficiency, particularly for a combined-cycle system using coal syngas.
• Heat transfer and material systems. Special alloys, advanced airfoil designs, novel cooling techniques and heat-protective coatings help to optimize performance of cooling features and turbine materials at extreme temperatures.
• Advanced transition sections. Changes in the design of the transition area between the combustion chamber and the rotating turbine offer the opportunity to reduce cooling air and leakage, cut nitrogen oxide emissions at higher temperatures, limit aerodynamic losses, and shrink the size of the turbine.
NETL’s goal is to move from bench-scale R&D to small-scale component testing by 2020, have full-scale pilot component testing under way by 2025 and effectively demonstrate 65% efficiency for utility-scale combined-cycle operations using natural gas and coal syngas by 2030 or sooner.
Combustion power plants already offer some of the most cost-effective, efficient and clean fossil fuel power cycles available, NETL said. NETL’s efforts to steadily improve these systems by developing advanced turbine components will help to not only rejuvenate the coal industry and stimulate the nation’s economy, but also promote responsible stewardship of the environment and ensure America’s continued energy dominance.