The HL-class’ combined cycle efficiency of over 63 percent is impressive. “In order to increase efficiency and improve performance, gas turbines have to be operated at even higher combustion temperatures – that’s the key,” explains Zhao. “We identified five levers to make higher firing temperatures possible.” Thus, his team developed an advanced combustion system that allows for higher firing temperatures, and at the same time more operational flexibility. Innovative, heat-resistant multi-layer coatings have been used to protect the blade material against the increased heat. But for the blades, Zhao points out, the inner values prove just as important: Superefficient internal cooling features have been engineered to improve the cooling process and hence efficiency. Furthermore, optimized sealing minimizes the leakage of cooling air. Finally, evolutionary 3D blading improved the compressor’s aero-efficiency.
Following this technology leap, is it time to take a rest? “On the contrary!” Ever the restless innovator, the CTO explains that, in the meanwhile, Siemens has already set its sights on the new threshold of 65 percent efficiency. “Speed in technology development is driven by digitalization, by additive manufacturing, by better collaboration,” he says. “And it has been rapidly gaining momentum: It took us ten years to break the 60 percent efficiency barrier, then another six years to improve to 61.5 percent. Now we’re taking the next step to 63 percent and beyond in under two years.” But as Zhao knows well, for Siemens’ customers, it’s not only about speed and efficiency – the solutions have to be above all reliable and cost-effective.