Vågaåna power plant

The Vågaåna power plant is located in Vindafjord municipality, Rogaland county. The operating waterway was constructed using new drilling technology. Learning experiences gained from this project open for new opportunities to build waterways through mountains, even for smaller projects.

History

The Våga farm is located by Hustoftvannet lake, between Imsland and Skipavåg in Vindafjord municipality. It has little arable land, but the larger outlying area is comprised of farms and a steep river.

The new power plant has an intake just below Vågastølen.The intake is located on property owned by many other farms at Hustoft and Skipavåg.

In 2003, a contract was signed with Småkraft, which assumed the risk, the work with the licensing process and the development itself. NVE granted a licence in 2007. The construction work began at the turn of the year, 2008/2009. In October 2012, the power plant ready to deliver its contribution in the form of new renewable energy and local business revenues.

The water from the Vågaåna river has previously been used for business purposes. In addition to the power plant, the river currently supplies a hatchery, Vågafossen Settefisk AS, located at the river’s outlet to the sea.

With its natural stone walls and a glass façade, the station building has an attractive exterior and has been nicely adapted to the terrain near the highway to Ryfylke. The Vågaåna power plant has become a facility both the landowners and Småkraft can be proud of!

The project

The implementation of the construction project has had its challenges. Construction in this steep terrain required a waterway through mountain.Småkraft chose to solve these challenges through a collaboration with Norhard, which carried out rock drilling as a pilot project for its directional drilling technology.

There is an advantage to drilling waterways through mountains, in that the solution ensures less encroachment on nature, and it may involve lower costs compared to the conventional tunnel/shaft solution. The project on the Vågaåna river has provided a great deal of learning experience and knowledge of how to complete future projects based on directional hard rock drilling.
In a pilot project like this, it is especially important to be able to tackle challenges as they come up. Experienced contractors along with experienced project management has undoubtedly been essential for tackling unforeseen problems during the project.

Technical information

The Vågaåna power plant has inflow from a catchment field of 5.1 km2. The intake at elevation 465 and the power station at elevation 38 gives a fall height of 427 metres. Power production is an estimated 9.8 GWh in a normal year. This corresponds with electricity consumption for 490 households. Minimum water flow is 50 l/s throughout the year.
The Pelton turbine has 4 nozzles with a maximum flow rate of 0.98 m3/s. It runs a 3800kVA 6600 v generator. All power is converted to 22 kV which is delivered to the grid. The intake dam is built as a blasted pool with a low dam in reinforced concrete, with a “shark cage” (prefabricated) as an intake construction. The intake blends in well with the terrain at the site and appears to be a very modest intervention. The waterway consists of 2 drilled holes at 150 and 720 metres, as well as 180 metres of trenched pipeline, with a diameter of 0.6 metres.
The 80 m2 power plant is constructed in the familiar Småkraft style, well-integrated into the terrain. Outflow is led through pipes into the river.

Technical data

Rainfall field

5.1 km²

Minimum water flow

Summer: 50 l/s

Intake elevation

465 m

Power station elevation

38,0 m

Drop height

427 m

Production

9,8 GWh
This corresponds to electricity 613 households.