Details of Chlus hydropower project firmed up: new solution features powerhouse in Trimmis and two interim powerhouses; still a challenge in economic terms

(PresseBox) (Klosters/Poschiavo, ) In September 2012, Repower announced that following a review of the Chlus hydropower project, a new option featuring a single powerhouse in Trimmis would be further developed. The revised project offers better value for money than the original solution. It harnesses the height difference between the existing Küblis power plant and the Rhine, and at the same time will support efforts to upgrade the ecology of the valley's river Landquart.

The previous plan was to have two sets of turbines using the water between Küblis and the Rhine, once in the Chlus and then again in the Rhine near Landquart. However, in the course of planning, it emerged that the project would not be economically viable. The environmental requirements, underground work in the Chlus, the pressure line between the Chlus and the Rhine, and, above all, plans to construct two powerhouses, turned out to be too expensive, and would have involved costs of approximately CHF 450 million. Repower was therefore forced to review the project and assess whether there were any feasible, lower-cost options to the original plan (see 27 April news release). After a thorough review of various options, as Repower announced on September 13 it was decided to concentrate on a single solution requiring only one powerhouse. In the meantime this new project has been further developed, and initial discussions have taken place with various interested parties (local authorities and environmental organisations).

Electricity for 45,000 households

The costs of the new Chlus power generation system will run to around CHF 350 million. The installations will generate around 214 gigawatt hours electricity (214 million kWh) a year, more or less equivalent to the electricity requirements of 45,000 households. In the current environment of very low electricity prices, the new solution remains economically challenging overall.

The main features of the new project are as follows:

Water intakes: Water that has passed through the turbines in Küblis will be fed directly into the new power generation system. Added to this will be water intakes on the river Landquart by Küblis and three side streams, the Arieschbach, Furnerbach and Schranggabach.

Main powerhouse: The plan is to build the main powerhouse in Trimmis industrial zone. There the water will drive the turbines before flowing into the Rhine. The Trimmis powerhouse will have an installed capacity of 55 megawatts. For comparison: The Küblis power plant has an installed capacity of 45.6 megawatts.

Pressure tunnel/pressure line: A 17 kilometre-long underground pressure tunnel will be used to take the water from Küblis on the left-hand side of the valley to a surge tank above Trimmis. Water captured in the three side streams will also be fed to this pressure tunnel. A 1.5 kilometre-long pressure line, also running underground, will take the water through the Molinära area to the powerhouse in Trimmis.

Interim powerhouses: The height difference between the intakes on the Arieschbach and Schranggabach streams and the pressure tunnel will enable two small powerhouses (3 MW installed capacity each) to be built there. These interim powerhouses will boost the efficiency of the system overall.

Equalising reservoirs: Equalising reservoirs will be built at both Küblis and Trimmis. The one in Küblis will serve as a buffer between the Küblis power plant and the Trimmis reach. The plan is to locate a surge reservoir in Trimmis to ensure the environmentally controlled feed of water back into the Rhine.

Taschinas 2

In 2011 Repower commissioned Taschinas power plant, which has been successfully generating electricity ever since. As part of the earlier Chlus project the plan was to use water flowing from the Taschinas powerhouse to drive a turbine at the Chlus powerhouse to generate even more power, rather than feeding it back into the Taschinasbach stream. Now that the Chlus powerhouse is no longer to be built, plans for the Taschinas 2 power plant will be developed independently of the Chlus project. The idea is still to use the water to drive a small powerhouse in the Chlus area.

Environmental investigations under way

The revised project is subject to the same statutory environmental assessment as the previous plans. Repower has the support of external partners in drawing up the environmental impact report, as well as in other areas. Work on the first phase of the environmental impact report is under way. Basically the new project also supports current efforts to upgrade the natural environment of the valley's river Landquart. On the one hand it will be possible to largely eliminate positive and negative surge resulting from human exploitation of the river. At the same time it will be possible to upgrade the two Mülbach streams and make the river passable for fish migration. The project thus supports Canton Graubünden's efforts to enhance the ecological quality of the river. Issues related to habitats for flora and fauna, the design of remediation measures and, generally, minimising the impact on people and the environment are all being taken into consideration.

What's next?

Repower is in close contact with the concession municipalities involved (the same authorities as under the previous plans) and the municipality of Trimmis, where the powerhouse will be located. Compensation for the local communities will be settled in the course of these concession negotiations. The goal is to move forward with negotiations so that the local authorities can present the concession agreements to voters for their decision in the course of 2013.

Once all licences and permits have been obtained and the decision to build has been made, Repower reckons it will take around four years to complete the plant.

Hydropower's contribution to the Swiss 2050 federal energy strategy

Both the federal government's 2050 energy strategy and Canton Graubünden's energy policy place increased emphasis on renewable energy. The Chlus hydropower project could make a substantial contribution to achieving these aims.

On the other hand the revised Chlus project demonstrates that despite calls for additional hydropower capacity in official energy policy, the economic framework can make building this capacity problematic.

A situation where the economic viability of even basically uncontroversial hydropower plants is not assured from the outset brings Repower back to the current support mechanisms for new renewable energy: because subsidies prevent the real generation costs from being reflected in the market price, other forms of generation - such as larger-scale hydropower plants - are put at a disadvantage, which can jeopardise their economic viability. For this reason Repower calls for more market-compatible promotional models that are more closely in line with the 2050 energy strategy than the current rules.

Repower continues to work to ensure that renewable energy generation can be expanded and create an optimum framework for this to happen. To solve the various problems involved, the company is working with all the relevant stakeholders, including environmental organisations in addition to the authorities, and has already presented the revised Chlus project to these parties.


Repower AG
Via da Clalt 307
CH-7742 Poschiavo
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