First horizontal, six-nozzle Pelton turbine in successful operation

23 January 2023

Loading of the 54-ton turbine housing at the Voith Hydro plant in St. Poelten

Voith Hydro has announced it has reached a new milestone in Pelton technology, with trial operation of the first horizontal, six-nozzle Pelton turbine having run successfully at the Gerlos 1 pumped storage power plant in Tyrol, Austria.

In the Pelton turbine, which is especially suited to plants with high heads, the water is directed by forming free jets at very high velocity from one or several nozzles to the Pelton runner. Until now, Pelton turbines with more than three nozzles have always been designed with a vertical shaft. The main reason for this was that it allowed higher efficiency than a horizontal arrangement. Voith Hydro said it has now successfully eliminated this drawback, as demonstrated in the Gerlos 1 power plant, where for the first time, an efficiency level comparable to that of the vertical configuration has been achieved.

The plant, which is operated by Verbund in the Ziller Valley in Tyrol with an annual output of 326GWh, saw four existing vertical Pelton turbines successfully replaced by one six-nozzle horizontal Pelton wheel.

According to Voith, 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, it said. The associated potential reduction in the number of turbines can likewise lower future maintenance costs. For new systems, as it requires less excavation and is more compact with a smaller footprint than conventional solutions, it could offer a shorter installation time, reducing overall investment costs, said Voith.