Kölnbrein Dam

The Malta power plants are a series of hydroelectric power plants in the Austrian state of Carinthia, consisting of the upper with the memory Kölnbrein (largest memory Austria ) and the main and lower level. Operator is the composite Hydro Power AG.

• 4.1 prestore Galgenbichl
• 4.2 compensation memory Gößkar
• 4.3 power plant Rottau

• 5.1 power plant Moelltal

History

The Malta project had a decades-long, shaped by different variants of preparation time. Already in the 1930s, employed the General Electric Company and subsequently the Alps Electric Werke AG with the use possibilities of the outflows of the Malta valley.

In the early 1950s continued the Austrian Draukraftwerke AG as part of the reorientation of the electricity industry continues the studies. The water-and energy- economic studies revealed that the interior of the Malta Valley is one of the wettest parts of Carinthia. The catchment area has strong glaciations, which constitute a valuable reserve runoff in dry summers. There will also be affected by weather events both north and south of the Alps.

On the basis of comparative studies to the nearby and then under construction in winter storage power plant Reißeck Kreuzeckgruppe should be expanded by some Beileitung Malta tributaries. The result finally was in a separate, comprehensive three stages, power plant group in the form of a construction-ready project on the use of Malta and the United streams.

From 1957 studied geologists underground and valley sides at the proposed location of the Kölnbreinsperre. Up to 80 m deep holes returned the rock as a stable base and abutment for the largest dam in Austria, which was cast in the years 1971 to 1978 from 1.6 million cubic meters of concrete: A horizontally and vertically curved vault wall, like an order 90 degrees tilted, flat dome is braced against the solid rock.

This design principle comes with considerably less building mass (concrete ) than any other dam of the same stability ( the approximate withstand six times the pressure of the water at full back ) and thus also saves construction costs. In 1979, the Kölnbreinspeicher first time the full back which exposes the dam by the water pressure of a total force of 5.4 million tons and project pursuant to 12 cm deformed to lock the crown out of the valley.

1978 signaled around 400 built-in measuring points problems: water squeezed through cracks at the base of the highest barrier blocks. Cause according to the expert judgment: overuse of the concrete barrier along the contact surface as a result of work in this area horizontal component of the water pressure, amplified by an unexpectedly large difference in the deformation behavior of the dam and mountains.

In a complex process, the wall of 1989 was restored to 1992 after a design by the Swiss lock experts Giovanni Lombardi and after approval by the dam Basin Commission: On the side of the valley, a 65 m high and 70 m wide support vaults 500,000 cubic meters of concrete and 150,000 m³ bulk was built. The water side lying cracks were sealed with cement and resin injections. The air side arranged stem relieves the barrier by about 22 per cent of acting with full back- water pressure. With this renovation, the construction costs for the power plant group Malta increased by an additional 2 billion shillings ( about 145 million euros ). On 4 October 1993, the full back was finally reached again at spot elevation 1,902 m - and all by then extended to 2,500 measuring points of the dam showed stability of the structure to.

Energy Economic Importance

The great adaptability of the power plant utilization in the short, medium and long -term fluctuations in demand is the most essential quality feature of the Malta power plant group.

While 91 percent of the available water supply in demand weaker summer half of the year and only nine percent occur in the winter months, the production share in the winter half year of nine percent can be increased ( from natural inflow ) to 78.3 percent through the years storage. By Wälzbetrieb contributed short and medium term to a further reconciliation of need Dargebot. In Wälzbetrieb can during the night water from the Möll in the memory of the main stage and the memory Galgenbichl be pumped into the storage Kölnbrein, to then be processed at peak load times. The power range between 406 megawatts and 891 megawatts turbine pump output power amounts to a total of 1,297 megawatts, or about twelve percent of the peak load in Austria. This can be quickly adapted to specific requirements in the interconnected system by the Malta KW electrical power. Due to the high performance and the early availability of Malta should be placed in a position, in case of failure of power plants, not only in Austria but also beyond its borders, with valuable assistance.

Advanced level

The upper level consists of the memory Kölnbrein, Kölnbreinsperre and the associated power plant Galgenbichl.

Memory Kölnbrein

The memory Kölnbrein is the core of the Malta power plants. The draining directly into the memory area is not sufficient alone to fill the annual storage in its entirety. For this reason, the tributaries of the Upper Lieser and several streams in the area of ​​Malta and Gößtales be taken at about 1,700 m above sea level and stored in prestore Galgenbichl. From there it is pumped into the 200 m higher memory Kölnbrein. In addition, water from the Möll is highly promoted around 1,300 m and used to fill the memory.

The water surface is at full back in 1902 meters above the Adriatic and can be lowered to 1,750 m. A full storage provides for the Malta power stations an energy content of 588.3 GWh.

The dam is a double curvature arch dam with air-side supporting vaults. 2,500 measuring points, of which 800 with direct connection to a process computer, monitor the dam.

Memory Kölnbrein at low tide

Kölnbreinsperre

The Airwalk

Monitoring tunnels in the Kölnbreinsperre

Measuring point for sliding gauge in the Kölnbreinsperre

Measurement point with solder in the Kölnbreinsperre

Establishment of the support arch Kölnbreinsperre (View from the lock crown, 1990)

Power plant Galgenbichl

The pumped storage power plant Galgenbichl generated in the turbine operating with the water of Kölnbreinspeicher Reservoir electric power, pump operation is pumped back excess energy water from the prestore Galgenbichl for energy storage in the memory Kölnbrein.

The power plant consists of two isogyre pump turbines ( Francis turbines ) in a horizontal arrangement. They drive two generators with a nominal apparent power of each 70 MVA. With an average gross head of 198 m and with a flow capacity of 70 m³ / s they can either deliver up to 120 MW of electrical power or up to 116 MW for pumping into the storage Kölnbrein spend ( rated power). The annual standard capacity is 76.0 million kWh. The power plant was 1977/1978 put into operation.

The machine hall of the power station Galgenbichl

Main stage

The main stage of the Malta power plants consists of the memory Galgenbichl, the memory Gößkar and the power plant Rottau.

Prestore Galgenbichl

The water already used the memory Kölnbrein and leads high-alpine streams are collected in memory Galgenbichl. This has two locking buildings, a gravel -fill dam with asphalt concrete surface seal and a concrete gravity dam.

Compensation memory Gößkar

Additional storage capacity provides the communicatively connected, around 10 km away Gößkar memory. This is also much closer to the leading to the power plant penstocks, so that unnecessary flow head losses can be in the 9.4 km long tunnel Malta avoided.

Butterfly Valve

Power plant Rottau

The machines of the Malta main stage Rottau in Kolbnitz in Moelltal are driven by water with extremely high pressure, which comes from the 1,100 meters higher saving. From memory Gößkar the path of the water through the 9.7 km long Göß and Hatteberg tunnels and a 1,850 m long, two-stranded penstock to the power plant.

The power plant has four jet Pelton turbines in a vertical arrangement. They drive four generators with a rated power of 220 MVA. Two of the generators are motor generators powering the two -stage and four -flow centrifugal pumps. At an average height of 1,106 m pipe case and with a flow capacity of 80 m³ / s can be either up to 730 MW of electrical power supplied or up to 290 MW are returned by pumping into the storage ( rated power). The annual standard capacity is 715 million kWh.

Kraftwerk and equalization tanks Rottau

Lower school

Power plant Moelltal

In the power plant Malta sub- stage, the water is used for the third time within the Malta power plants for generating electric power.

In balancing reservoir Rottau is the worked off water from the main stage and water from the Möll. At least 5 m³ / s of this water flow either through the weir Rottau or by a turboprop engine with 630 kW rated power in the Möll. All other water passes through the open, about 2.5 km long headrace channel and the Saxons path tunnel, at a height of 45 to a design flow of 110 m³ / s and m, the power station Moellbruecke. This is 3.9 km straight line from the beginning and 1.2 km from the end of the headrace. There, it is processed through two Kaplan turbines with a vertical shaft. The annual standard capacity is 120 million kWh.

The water still comes before the actual Möllmündung in the Drava, where it is used again for power generation in Carinthia ten run power plants. The Möll loses on the upstream channel a substantial amount of water, which is why only a fraction more than the natural river bed flows into the Drava River.

Lock in Rottau, behind the natural riverbed of the Möll

End of the headrace and the beginning of the underground Sachsenwegstollens

Power plant Moelltal

Tourist importance

In addition to the energy industry, especially the reservoir Kölnbrein also has tourist importance.

The 14.3 km long Malta High Alpine Road takes you past spectacular waterfalls, which dry up during the night because the water is diverted into the storage lakes. Through the tunnel leads to the mountain restaurant and hotel Malta, next to the Kölnbreinsperre. The tower-like building houses next to the restaurant and 60 beds also show information about the power plant group, a collection of minerals, and an information exhibition on the National Park Hohe Tauern.

It serves as a starting point for hikes and mountain tours. From the crest of bungee jumping jumps are organized. The up to 4.3 km long reservoir is also used in the summer months of the rowers from Germany aft for high altitude training in preparation for the World Championships and Olympic Games.