First horizontal, six-nozzle Pelton turbine – Voith Hydro sets new benchmarks at Gerlos 1 power plant

In addition to this application, the technology is of particular interest for upgrades of existing hydropower plants where single- or double-nozzle horizontal units are already installed. This is because the turbine can be replaced without major structural works, which significantly reduces civil costs and installation times. At the same time, there is enormous potential for increasing efficiency. The associated potential reduction in the number of turbines can likewise lower future maintenance costs. The new development is also a winning solution for new systems, as it requires less excavation and is more compact with a smaller footprint than conventional solutions. This is also associated with a shorter installation time, which substantially reduces the overall investment costs. 

The interaction between the water jet and the buckets of the Pelton wheel is extremely short, often just a few milliseconds. This is why the flow simulation of Pelton turbines is by far the most complex and difficult of all hydraulic turbomachinery simulations. Voith Hydro has refined the methods in recent years such that the housing flow can now also be analyzed. This important advance also made a significant contribution to the development of the new concept. 

Since the beginning of the 20th century, Voith Hydro has supplied thousands of Pelton turbines in a wide range of sizes and outputs all over the world. For many years now, the company in Germany has been conducting intensive research on the concept of multi-nozzle, horizontal Pelton units. The resulting developments of all horizontal Pelton turbines with more than three nozzles are grouped under the designation “HP3+”. 

Last year, Voith Hydro experts presented the technology at a leading hydropower conference in Vienna. This world premiere was preceded by extensive tests and pilot programs at the company’s own R&D center in Heidenheim. The first customers, including Austrian utility Verbund, are already using the innovative design. 

The Gerlos 1 power plant is a pumped storage facility in the Ziller Valley in Tyrol. Commissioned in 1949, it has an annual output of 326 GWh, allowing it to supply renewable energy to more than 70,000 four-person households. 

Even before the new unit was commissioned, the spectacular transport operation for the turbine housing was already causing a stir. At the beginning of April 2022, this 54-ton giant left the grounds of the Voith Hydro plant in St. Poelten, Austria. Apart from its weight, the dimensions of the unit were also impressive: just under nine meters long, more than six meters wide and over four meters high. This logistical masterstroke could be accomplished by means of a heavy transport operation taking an entire three nights.