“The thing that’s special about our invention is that the new cooling system is inherently safe, meaning that it doesn’t need its own active drive units,” explains Wechsung. The cooling system can therefore never break down and is always on when the steam turbine is in operation. The higher the steam’s temperature, the more effectively the steam turbine generates electricity. The critical aspect of steam turbines is their high temperature of about 600 degrees Celsius, which is brought to bear on the blades by the hot steam. Most of the materials used for the blades, bolts, valves, and seals cannot withstand this heat and therefore need to be cooled. To solve this difficulty, Wechsung and his colleagues came up with the idea of diverting some of the steam that had already cooled off a bit on its way through the turbine and using it to cool the areas that are subject to particularly high temperatures. When the recirculated flow of steam encounters the parts to be cooled, it reduces their temperature from 600 degrees Celsius to about 520 degrees Celsius.

“The new principle has made it possible to work with fresh steam temperatures of 600 degrees Celsius in the steam turbines without having to use expensive and untried new materials,” explains Wechsung. This is the only way that new steam turbines can be made using conventional materials. Another factor that is of particular importance for ensuring the steam turbine’s flexible operation is that the walls of the turbine would have to be much thicker without the new cooling system. This would make starting or shutting down the turbine much slower, as the thermal stresses would otherwise be too great. Instead of the rather sluggish baseload power stations of the previous generation, the changed electricity market now urgently needs “high-speed” steam turbines that can quickly supply electrical power.

The first power station to feature the new steam turbine design was constructed in China, where the blocks went into operation in 2006 and 2007. Each of the Yuhuan power plant’s four blocks has an output of 1000 megawatts and an efficiency of 45 percent. The plant’s operator, Shanghai Turbine Company, a Siemens licensee, now has about 50 similar facilities on order, under construction or already in operation. Six ultra supercritical steam turbine power stations featuring Wechsung’s invention are being planned or are under construction in Europe. Four of these are in Germany (two in Westphalia and one each in Lünen and Mainz), while two blocks are in Eemshaven, Netherlands.

Wechsung has registered a total of 19 inventions which have resulted in 56 granted individual patents and 14 IPR families. He has made inventions for the fast cooling of steam turbines, for example, as well as for improving operating flexibility, optimizing the steam supply for cogeneration purposes, and capturing and storing carbon dioxide (CCS). Wechsung has most recently begun to address a very hot topic. He and his team have developed initial steam turbine designs for solar thermal power plants, in which solar energy produces steam that drives a turbine. The solar power plants use many mirrors to focus the sun’s rays to generate the steam that drives the turbines which produce electrical energy. The power stations incorporate the experience gained from the development of steam turbines for a wide range of well-known applications. The solar power stations are a key component of the Desertec project, which will conduct electricity generated in various desert regions to Europe via “electric highways.”

Wechsung attended school in the former GDR, where he was also trained in parallel as a power plant technician. He subsequently studied power plant engineering in Odessa, USSR (now Ukraine) before commencing his professional career at Siemens’ steam turbine production facility in Mülheim, Germany.