Heavy Duty Conveyor Drives at Hydroelectric Plant Construction

Belt Conveyor Drive Systems

Heavy Duty Conveyor Drives at Hydroelectric Plant Construction

Industrial Gear Units at “Linthal 2015” Construction Site in Switzerland
To stabilise the power grid, Swiss supplier Linth-Limmern AG extends its existing Limmern power plant by a pump storage system. Most of the necessary installation is situated underground, and during construction a huge amount of rock material had to be moved from almost 600 m inside the mountain.
(ed. WoMaMarcel - 27/7/2015)
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“Linthal 2015” construction in progress: pumped-storage infrastructure is an invaluable element of assuring reliable power supply.

In an extremely demanding construction project in the Alps, almost 600 m inside the mountain, large chambers have been excavated to form the new, high-capacity pumping station of Switzerland’s largest hydroelectric undertaking in modern times. Mastering a 45 degree incline and a height difference of approximately 180 m, two belt conveyors transported approximately one million tons of excavated material over the course of three years. They were driven by heavy-duty industrial gear units from Nord Drivesystems which, now that their job in the Alps is done, are being recommissioned for their next assignment.

Power consumption typically peaks at midday and in the evening and dwindles down at night. Power distribution networks must therefore be regulated to ensure reliable supply. Complicating this task, the emphasis on developing wind energy plants in coastal regions brings about an increase in the so-called stochastic energy, which cannot be reliably planned due to random wind conditions. In contrast to nuclear power plants and river-based hydroelectric power stations, which are the main source of energy in Switzerland, pumped-storage plants can rapidly respond to changes in demand. Unlike conventional hydropower plants with only an upstream reservoir, pumped-storage stations cannot just generate energy at peak times but also store excess power. They have two reservoirs at different altitudes. Water flowing from the upper reservoir powers turbines connected to generators. The electrical power is fed into the grid while the water flows into the lower reservoir. At low-demand times, it is pumped back into the upper reservoir using power from the grid. For instance, excess wind power generated in off-peak times can be used to pump water back into the upper reservoir. If there is no wind during the day, the pumped-storage stations can cover the power deficit.

Record Infrastructure Project

Swiss energy supplier Axpo is close to finishing the demanding large-scale Linthal 2015 construction project. Switzerland’s largest hydroelectric undertaking will increase the overall output of the existing Linth-Limmern power facility from 480 MW to 1480 MW. A new underground pumping station will pump water from the Limmernboden reservoir at an altitude of 1860 m above sea level into lake Muttsee about 600 m higher up. Kraftwerke Linth-Limmern AG, a member of Axpo Holding AG, is overseeing the project. The scope of Linthal 2015 includes the construction of a new large dam that will increase the storage volume of the upper lake from the present 9 to 25 million m³. The existing compensating reservoir at an altitude of about 800 m is being expanded.

Two conveyors in one tunnel: the upper belt moved downwards and the lower one went upwards.

Work has been carried out at different altitudes, but for the most part inside the mountain where a new underground pumping station and extensive tunnel system are being constructed. The machinery chamber is located at an altitude of about 1700 m and some 600 m into mountain. It is 150 m long and 30 m wide with a maximum height of 53 m. A separate transformer vault is about 130 m long, 20 m wide, and 25 m high. Additionally, there are numerous water tunnels, parallel pressure shafts, and other service tunnels.

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