Substantial investments are being made in dam safety on the river Dalälven in Sweden. An extensive rebuild is planned for the 100-year-old Forshuvud hydropower project. In total, Fortum will invest approximately €45 million during the expected timeline. Investments like these are necessary to keep hydro as a cornerstone in Swedish carbon dioxide-free electricity productions, and to balance more weather-dependent types of power.

Forshuvud hydropower plant dates back to the 1920s and despite refurbishments in 1990 and 1998, the original power station remains part of the dam. The plant has an output of 44MW and produces approximately 229GWh of electricity annually. Thus, it is an important component of the Swedish energy system. In 2019, Fortum also installed the Nordic region's largest battery plant at Forshuvud. The battery enables faster regulation of the frequency in the electricity grid with less wear on turbines and generators. 

The battery solution also reduces the wear and tear on turbines and peripheral equipment, resulting in equipment lasting longer while the power plant can deliver control power faster. The battery's total storage capacity is 6.2MWh, with an output of 5MW.


This investment is very much about safety, for the staff at the facility, for the surrounding environment and for the operation of the business. The project will deliver sustainable solutions for dam safety and continued efficient operations.

In addition, the construction work has aimed to be carried out with an environmental focus throughout the process. Fortum aims to reduce its business climate footprint in all sectors and throughout operations, including the renovation of power plants.

An important part of the renovation and rebuilding at Forshuvud was to replace a large part of the original concrete from 1918. Concrete traditionally consists of cement, stone and sand in different fractions, and water. When cement is manufactured, a lot of carbon dioxide and emissions are formed, and before the project started, we investigated if we could produce concrete in a more climate-friendly way.

 In both 2017 and 2019, we involved students from the Royal Institute of Technology in Stockholm (KTH) who did their thesis together with us at Fortum. The first thesis investigated the possibilities of lowering the temperature that forms when rough concrete structures are cast. Studies were conducted on adding fly ash in combination with coarser aggregate in the concrete, along with using ice as cooling instead of water, which lowered the temperature and also reduced the risk of cracks in the structure.

 The second thesis took up where the first ended. The purpose of that work was to practically carry out tests on the concrete mix that was produced in the first. The tests were carried out at the concrete industry's concrete station in Gävle and it has turned out that the concept concrete that was developed with the help of the students is just as good to use as a traditional variety. 

Hence, a reduction in climate impact was achieved compared to using traditional concrete, which means that Fortum will now replace approximately 6000m3 of the concrete in Forshuvud with the more climate-friendly version of the total volume of concrete of about 9000m3. This results in a saving of around 500 tonnes of CO2.

Comprehensive update and modernisation of Trängslet dam

The 300MW Trängslet project is located on the river Österdalälven in Sweden and produces an average of 651GWh a year. Plans to update the dam were started in 2008, and since then preliminary studies have been carried out and applications were approved in 2017. Construction work started in autumn 2019 and are expected to be completed mid-2024.
At 125m, Trängslet is the highest dam in Sweden and the largest regulating reservoir among Fortum's power plants. The regulating aspect of dams is important since it enables hydro to balance fluctuating effects from weather-based power sources. Construction of Trängslet began in 1955 and was completed in 1960. During its construction time, it was one of Europe's largest establishments. Trängslet has been updated and refurbished several times, but never as extensively as this project. 

An important part of the modernisation is to increase the possibility to handle the spill. A new deep excavation will be built in an existing bypass tunnel, built under the dam in the 1960s. In addition to this, the dam hatches will be updated and the dam itself will be further strengthened. The support filling will be reinforced with as much as 250,000m3 of rock. When all work is completed, Trängslet is estimated to be able to handle a 15-20% increase in water flows. 

In total, this involves an investment of approximately SEK 600 million. The work being conducted will improve safety and prolong Trängslet’s life span as a reliable part of the fossil-free power system.

Innovative fishways on the river Dalälven

Fishways are set to be built at the Väsa and Blyberg hydropower projects in Älvdalen municipality, and Spjutmo in Mora municipality, all along Sweden’s river Dalälven from 2022-2025.

At Spjutmo, Väsa, and Blyberg hydropower plants major undertakings are being made to build fishways. Fortum is committed to several climate and environmental targets, which include the goal to implement significant voluntary measures to promote biodiversity at a group level. 

Fishways are important parts of the company’s biodiversity work. However, installation of such complex systems at pre-existing powerplants like the 35MW Spjutmo and 15MW Blyberg, require innovative ideas and some serious engineering skills.

After many attempts to facilitate fish migration with various new innovative solutions, the investments made in this project are the largest in Swedish history. Fortum is satisfied with the technical solutions that will be used, which benefit both grayling and trout.

The solution consists of several parts. Firstly, a mammoth pump is used to supply extra lure water at the entrance of the fishway to attract the fish. A mammoth pump uses air and drop height to make a small water flow above the dam significantly larger on the downstream side. The fishway is built in storeys, where it goes over itself, like a ramp in a parking garage. In that way the installations use the surface more efficiently, since it is tight to fit such large fishways into existing facilities.

For fish migrating downstream, passage past the power plant is made with the help of an inclined fine grid in combination with a diverter. The fine grid does not go down deep since the smolt, young salmon fish, prefer to swim near the water surface. 

The fish are then guided along a channel made of mostly prefabricated concrete that is approximately 560m long and 4m wide. Before it can be built up masses of rock must be excavated which at most it will be a 19m deep shaft. 

The upstream work at Blyberg and 15MW Väsa is expected to be completed in 2025 and the fishways downstream should be ready and in operation in 2023. The dams at Sjutmo, Blyberg and Väsa will also be closed during the fishway work.

As this project is the first of its kind in Swedish history, the exact outcomes are hard to predict and depend on various factors. Fortum is hopeful that the innovative fishway solution will gain successful results, which will be evaluated when the project is finalised in 2025.

Updating of Ätrafors hydropower plant in Sweden

A large upgrade project is currently underway at the Ätrafors power plant on the river Ätran in Sweden, where all three units are to be improved. The first, or number 3 as it is named, has been completed within the first SEK 43M part of the project which – besides a turbine upgrade with a new Francis wheel – also included a refurbished generator, intake gates, electrical control equipment, a new control room and general paintwork. On top of that, an installation of 153 solar power panels has been mounted, supplying the plant with a maximum power efficiency of 54kW. 
Safety improvements were also carried out as better lighting was installed along with the mounting of new stairs and obstacles, creating physical protection from moving parts within the plant.

Replacement of the circa 100-year-old unit with new technology also comes with an expected increase in maximum efficiency and a new turbine efficiency of 3.8MW.  Work will now start on units 1 & 2 at a total cost of about SEK 35M. This will cover renovation of the turbines, including new runner and guide vanes as well as a renovation of the generators.

With these improvements Ätrafors’ annual production is set to increase by 7.9GWh – where unit 3 alone contributes 3.1GWh to the total. 

Extensive investment in the Umeälven

Three power plants in the province of Lapland in Finland are set for modernisation from 2033-2024.

Fortum and German energy company Uniper have recently applied to the Land and Environment Court in Umeå for permission to modernise three hydropower plants on the river Umeälven. The modernisation is estimated to cost SEK 865million and includes a new unit and rebuilding of all six existing units. 

 Uniper's three power plants Bålforsen, Betsele, and Hällforsen are a bottleneck during certain periods as they have a lower so-called "sucking capacity" than the power plants located upstream and downstream in the Umeälven. To address the bottleneck, Uniper and Fortum intend to expand that capacity.

 The modernisation includes the construction of a completely new unit in Bålforsen's power plant. Indeed, when Bålforsen was built in the 1950s preparatory measures were taken to be able to install another unit in the future. However, simply expanding the Bålforsen power plant with a third unit does not solve the problem with the bottleneck but pushes it further downstream towards Betsele and Hällforsen. The project, therefore, includes an upgrade of existing aggregates in Bålforsen, Betsele, and Hällforsen so that all of these get an extended draining capacity and thereby increase the ability to deliver electricity in the best possible way.

 The increased flexibility also means increased opportunity to deliver the support services that the market and the electricity system need.

 Hydropower is becoming increasingly important for the Swedish electricity system. The need for flexibility and regulation is now increasing dramatically as weather-dependent power generation has expanded. Therefore, Fortum says it is also significant that it takes advantage of the opportunities available to make the facilities more efficient, optimised, and profitable. 

The water verdict is not expected until 2023, and if the outcome is positive, work can begin in 2024. 

Refurbishment of the Utanen hydropower plant in Finland

The 64MW Utanen hydropower plant on the Oulujoki River was completed in 1957 in Utajärvi, Finland. Three vertical Kaplan turbines have an average annual production that covers the electricity use of about 13,000 households with heat.

The Utanen power plant has three units of which unit 3 was refurbished in 2005. A 20million euro refurbishment of units 1 and 2 was executed in two phases during 2020 and 2021. This also included renewal of the plant’s medium voltage switchgear and main transformers, plus upgrading of the automation system. 

Refurbishment of units 1 and 2 has increased the output of the Utanen power plant by 6MW. It was considered as being timely as both units were nearing the end of their useful lives. 

Fortum says the refurbishment enables them to keep the power plant’s production availability at a high level, and enables the production of more energy from the same amount of water. The Utanen plant is now more efficiently generating hydropower which, thanks to its flexibility, is important for maintaining balance in the power grid. 

The Oulujoki water system plays a significant role in the production of domestic, renewable energy, so it’s important to keep the plants in good shape. The next main machinery refurbishment to be carried out on the Oulujoki River will be at the Pälli power plant during 2023–2024. Meanwhile, there are ongoing investments to maintain and improve availability of Fortum’s 11 hydropower plants in the Oulujoki water system which have an annual average output equivalent to the annual consumption of about 120,000 electrically heated households.