Stories

The rehabilitation of Nordic hydropower plants will ensure effective operation for the next 50 years. Anette Småbrekke manages the rehabilitation of the Lio hydropower plant from 1969.

Map of Norway

Lio hydropower plant

> Built in 1969

> Upgrade includes new control unit, rehabilitation of generator and turbine, rehabilitation of waterway, new transformers, switchgear for power plants Lio, Byrte and Skafså, civil engineering work

> After the upgrade, installed capacity will increase by 3 MW to 43 MW. Annual production can be increased by up to 18 GWh for a total of 243 GWh

> Completion in 2017

> Total investment for the project is NOK 200 million

Telemark shows its best side on this autumn day. Orange trees are bathed in the light of the low sun along County Road 38 between Amot and Dalen. Lio hydropower plant, located about halfway along the winding road, has been producing electricity since 1969, and is wholly owned by Statkraft.

"Most Norwegian hydropower plants were put into operation in the 1950s and 1960s and are now in need of rehabilitation," says Statkraft's project manager Anette Småbrekke.

"The upgrading of Lio power plant has been discussed for the last 20 years, so we're happy that it's finally happening."

A total of NOK 12 billion in reinvestment in Nordic hydropower plants is planned for the period 2014‒2018. Lio in Tokke Municipality is the largest hydropower project initiated in Norway this year. The power plant is located 400 metres inside a mountain and utilises a 352-metre-high fall from the Byrtevatn intake reservoir.

Anette Solbrekke
The local community is very pleased about the road being improved.

Long and heavy load

This is the first time we've assembled so many elements in one big project," says Småbrekke. "The preparatory phase has been long, and it was a big day when we finally got the project approved by group management."

An independent consultant looked at the social benefits of various rehabilitation options before the solution was chosen.

The overall project consists of five parts: construction, transformer and set-up, control unit, waterway and generating unit. The current three-winding transformer inside the plant will be replaced with a pair of two-winding transformers; a production transformer inside the plant and a grid transformer outside.

"We're going to rehabilitate the generator and turbine inside the plant, along with the tunnel and penstock in the waterway," says Småbrekke. "We're also getting a new control unit and transformer from Slovenia. It's been quite a challenge to figure out how to ship the 180-tonne transformer here. The total weight including the 71-metre-long transporter is 340 tonnes."

The solution was to ship the transformer by boat to Åkrafjorden and then transport it by road over Haukeli Mountain.

Road improvements

The transformer is specially designed to fit in the Haukeli tunnel," says Småbrekke. "We’ve also started working on the county road to be able to drive the transporter right up to the power plant."

Four s-turns will now be improved and a bridge reinforced to allow the transformer to be transported safely in August 2016. The upgrade is being completed by the Norwegian Public Roads Administration on contract from Statkraft. County Road 38 is known for its many bends and poor standard in places.

"The local community is very pleased about the road being improved," she says.

The upgrading will also help to secure the power supply to the local community. Now we'll have two transformers instead of just one.

Hectic activity

The current transformer is located inside the power plant, but the upgrade will result in a separate transformer building on the outside.

"It's never a good thing to have oilfilled transformers inside a mountain due to the danger of fire and explosion, so this will be a huge improvement," says Construction Manager Tor Ole Solheim.

There is a hectic level of activity at the construction site. Sandwiched between the mountainside and the Tokkeåi River, an excavator is digging out a site for the transformer building, directly under power lines carrying 300,000 volts.

"There is a safety clearance of five metres," he says. "The safety manager is always on site because work is taking place within a defined high voltage area. It's a challenge to blast rock so close to power lines – we had to shield a lot and use small, controlled explosions," he continues.

The project also requires careful monitoring from an environmental point of view.

"Water from the plant flows into the river where there are a lot of brown trout, so it's popular among fishermen," says Solheim. "We take good care that no oil or diesel from the plant ends up in the river."

Lio power plant turbine

Important hub

Lio power plant is an important hub for electricity supply in Western Telemark, and feeds power to both the local and national grids. In addition to Statkraft, Vest-Telemark Kraftlag power utility and Statnett are connected here.

The annual average production from Lio is 225 GWh, which is equivalent to the electricity consumption of 11,250 households.

After upgrading, the capacity will increase by about 18 GWh, equivalent to the consumption of around 900 households.

"Lio is a connection point for Vest-Telemark Kraftlag and has been a bottleneck for them," says Construction Manager Tor Helge Midtbø. "The utility hasn't been able to produce at full power because the grid transformer at Lio is too small. The new transformer will make maximum production possible."

Vest-Telemark Kraftlag will therefore cover 40 per cent of the cost of the new grid transformer, with Statkraft picking up the remaining 60 per cent.

"The upgrading of the transformer will also help to secure the power supply to the local community," says Småbrekke. "Now we'll have two transformers instead of just one."

Tokkeåi river

Anette Solbrekke

Long-term perspective

Anette Småbrekke and the other 45 Statkraft employees in the Tokke-Vinje area have their office in Dalen. From here they have responsibility for 18 power plants in Telemark and Buskerud Counties.

"I received my mechanical engineering degree from Buskerud University College and am now working on a master's degree in project management from the Norwegian University of Science and Technology," says Småbrekke.

"Hydropower is an exciting field, and since I started working at Statkraft in 2002, interest in green power has exploded."

When the upgrade of Lio power plant is finished in 2017, the plant will produce renewable energy for years to come.

"Since no new concessions are being granted to develop power plants in Norway, it's important to maximize capacity in existing plants. The new control unit has a life expectancy of 20 years and the transformer can last up to 70 years."    

Text: Sissel Fantoft
Photo: Kim Ramberghaug
The article has also been published in Statkraft's magazine People & Power no. 1/2016

Since no new concessions are being granted to develop power plants in Norway, it's important to maximize capacity in existing plants.