The newly built small hydroelectric power plant “Lavant” of Verena and Wolfgang Pichler has been generating clean energy in the Styrian “Zirbenland” for more than a year now.

The operators are completely satisfied with the plant, which was realised both technically and visually in an exemplary fashion, and can annually generate around 2 GWh of green power. A 3-nozzle Pelton turbine of the manufacturer ANDRITZ Hydro with a maximum output of around 450 kW is used as an energy supplier. In the interest of the value creation chain, the know-how of regional companies was relied upon to a great extent for the construction of the project. In addition to the aspect of effective current production, the operators attached great importance to a structural realisation of the control centre and the weir in a manner as natural as possible that was also adapted to the landscape.

The so-called “Zirbenland” in the area of the upper Murtal, with its varied hiking options in a natural mountain land­scape, is a popular destination for those seeking leisurely relaxation and athletic challenges. The heavily forested region is known for its high quality products made of wood and the aromatic cones of the Zirben pine. Not least, the landscape with its many streams offers optimal conditions for hydroelectricity. This potential was also recognised by Verena Pichler, who began examining initial concrete ideas for the construction of a diversion plant on the Lavant. “While the first construction applications were rejected in 2013, following an aquatic ecology revaluation of the Lavant carried out in the following year, the responsible authorities finally gave a green light in 2015 for the planned power plant”, says Verena Pichler.

PROVEN STYRIAN COMPANY UP AT BAT
The Guster Gottfried GmbH was commissioned with the entire structural and civil ­engineering, as well as with the manufacture of the pressure pipeline. At the local inspection in mid-January with temperatures eight degrees below zero, the managing director appeared to be very satisfied with the project completed a few months ago. “Nobody is really surprised when a power plant fails to operate under such icy conditions, but power production continues uninterrupted here”, builder Guster praised the power plant, which commenced operations for the first time in September.

WEIR WITH SIDE EXTRACTION
The water catchment of the Lavant power plant basically consists of a classic diversion structure with side water extraction. A 4 m wide and 1.6 m high back-up flap with a ­hydraulic drive is used to dam the water. The infeed guard at the end of the fish ladder, as well as the flushing gates and gatehouse ­guards are also moved hydraulically. Coarse and fine screens including an automatic ­telescopic screen cleaner ensure an optimal flow prior to the start of the penstock, while a subterranean desanding basin serves to discharge the fine sediment.

CAST PIPELINE
A total of 1,749 m of cast-iron pipes of the JINDAL SERTUBI brand with a clear width of DN600 were laid for the production of the pipeline. Due to the route along complex terrain, the operators decided in ­favour of the proven robust material. The ­extremely durable pipe system, with its user-friendly socket system, stands for the best laying conditions and also convinces with its robust material properties with a long service life and pressure resistance. The high quality pipes were delivered by the Upper Austrian sales specialists Geotrade from Ried in the Riedmark.

CONSTANT ENERGY PRODUCTION IN THE DEEPEST WINTER
When choosing the electromechanical equipment for its new power plant, the Pichler family decided in favour of a highly efficient 3-nozzle Pelton Turbine of the ANDRITZ Hydro brand. When the complete extraction water quantity of 450 l/s is available to the turbine equipped with electrically regulated drive nozzles at the commencement of the snow thaw in spring, this can achieve a maximum output of 449 kW with a gross drop of approx. 120 m. A synchronous generator from the manufacturer Hitzinger coupled directly with the turbine shaft serves as a current transformer. Analogously with the turbine, this turns at exactly 750 rpm and has a rated apparent power of 500 kVA. The on-­site appointment of zek Hydro proved that the turbine also reliably generates power even with a considerably reduced flow and significant icing of the upper water layer. Despite temperatures well below the freezing point and a fraction of the extraction water quantity, the machine set was consistently on the grid with an output of nearly 80 kW. The operators anticipate energy production of around 2,000,000 kWh in an average year. The generated current is fed entirely into the public power grid.

ELECTRICAL TECHNOLOGY FROM THE PROS
Another Austrian company, the MBK Energietechnik GmbH, was also able to distinguish itself with the delivery and proper installation of the entire electrotechnical equipment to the powerhouse and weir. The scope of services of MBK also includes the commissioning of the energy distributor and the programming of the fully automated plant control system. The machine was synchronised with the grid for the first time on 29th September 2016 and has since then provided energy for the public grid. Except for a few grid disruptions in the course of the winter, there were no production interruptions – not even the dry autumn and the quite frosty winter could have a significant effect on the plant.

RESIDENTS PROFIT FROM CONSTRUCTION WORKS
A highly welcome auxiliary effect for the residents of a small settlement near the power plant was the creation of the new, subterranean power route for energy diversion. “As a result of these in any case necessary construction measures, the residents received a reliable connection to the public power grid. Failure due to storms or line damage as a consequence of snow load are thus no longer a problem”, says Verena Pichler. In order to also optimally mediate the practical implementation of local green energy production on location to passing hikers, the operators want to erect an illustrative information panel explaining the function of the power plant prior to the start of the tourism season. The project realised in an exemplary fashion deserves this attention, plant operator and builder agree.