What impact does hydropower have on the environment?

Hydropower is requisite to our having a safe and secure electricity system based on renewable and fossil-free electricity generation, and hydropower has a unique ability to constantly adapt production to meet society’s needs. However, hydropower has an impact on its immediate environment and the biodiversity of developed watercourses.

Environmental measures where they help the most

In many places, primarily in minor watercourses where hydropower’s contributions to energy production and the power balance is relatively small, local environmental remediation at plant locations can be prioritized. At Uniper, we support the trade-off between, on one hand, the importance of hydropower to the climate and electricity system, and on the other, the requirements for local environmental remediation agreed to by our politicians.

Demolition of dam at Marieberg powerplant 

The Mörrum River is a body of water with significant natural value and is widely considered to be Europe’s best recreational fishing spot for salmon and sea trout. Uniper has an extensive history of voluntary measures to benefit the environment and the biodiversity of the Mörrum River, such as fishways by the Hemsjö Övre and Hemsjö Nedre powerplants. These measures were justified by the substantial environmental benefit and the relatively small production loss, which was also true for the demolition of the dam at the Marieberg powerplant. The latter being the natural next step, since the powerplant is furthest down the river and the demolition improves potential passages for fish and other organisms, provides access to reproduction areas and reinforces the effects of previously implemented measures. The goal is to restore the stretch of river by the dam to its state prior to the construction of the powerplant more than 100 years ago.

The project is financed by Uniper, the Swedish Agency for Marine and Water Management, Sveaskog, Life Connects, Good Environmental Choice and Foundation Östersjölax.

Meet Johan, who works with hydropower environmental issues



Fishways at the Faxälven River

Unrestricted fishways past the powerplant

We are voluntarily investing in environmental improvements in several ways. For example, by installing fishways by several of our powerplants. At the moment, work is ongoing to install three fishways in the upper Faxälven River, which will create about 150 kilometers of unrestricted migratory routes in one of Sweden’s major regulated watercourses.

In addition to these voluntary initiatives, all power companies are obligated to compensate for encroachments caused by hydro power construction, in accordance with the terms and conditions for each power plant. This may involve various operational measures or adjustments, as well as district taxes and fishing fees. These funds are earmarked for increasing the quality of life around the watercourses in various ways. We pay approximately SEK 20 million in such fees annually.

Eight hydropower companies, including Uniper, have taken the initiative to launch an environmental fund to improve the aquatic environments of Swedish hydro powerplants. The fund’s mission is to finance environmental measures to enable Sweden’s hydro powerplants to fulfill modern environmental conditions. The Hydroelectric Environmental Fund is one of Sweden’s largest financiers of investments in the environment.

Follow Carl Gustav as he helps the eels to reach the sea


Powerplants and eels

European eel stocks are seriously endangered and the EU’s Eel Regulation highlights measures such as reduced fishing, improved migratory options for bypassing powerplants and other migratory obstacles, as well as the introduction of eel fry to reverse the trend. One method that Uniper is working with is to capture and transfer the eels past any powerplants they need to pass to reach the sea. The first powerplant in the country to use this technique was the Ätrafors powerplant in Ätran. The measure is part of Krafttag Ål, which is a collaboration between the Swedish Agency for Marine and Water Management and major power companies, aimed facilitating more eels to reach the Sargasso Sea.

The eels spawn and die in the Sargasso Sea, north-east of Cuba. After the larvae are hatched, they travel with the Gulf Stream to the coasts of Europe. It is a journey that takes anywhere from ten months to three years. At this stage, they are known as glass eels. Many remain in the coastal regions, while others continue their migration up rivers and streams. Gradually, they develop a yellowish pigmentation and are called yellow eels.

Some 10 to 20 years later, the eels change again and are called silver eels. This is when they begin their long journey back to their birthplace in the Sargasso Sea, where they spawn and subsequently die.

Gentle trapping facility on the Mörrum River 

Since 2011, Uniper has had a trapping facility in the Mörrum River that allows us to catch, weigh and measure the eels, and then release them downstream from the powerplants. In front of the power plant’s water intake, there is an oblique grating that prevents the eel from ending up in the turbines, where they could get hurt and possibly die. The grating has openings, through which the silver eels can enter. Once in, they follow a conduit which, by means of consistent negative pressure, flows into a container where the eel is collected. The eel are then transported by road – bypassing a total of six powerplants by the Mörrum River – and released near the estuary.

In addition to Mörrum River and Ätran, there are similar trapping facilities, including at Emån, and several more are planned. The technology has been developed by Uniper, jointly with researchers from Karlstad University and, with the right conditions, is a well-functioning solution that helps fish to migrate downstream past the powerplant.

The pros and cons of hydropower

Focus on the climate and environmental improvements

The energy supply should always be viewed from different perspectives. As an energy source, hydropower has its pros and cons. To reduce negative environmental impact on biodiversity as a consequence of hydroelectricity generation, voluntary and statutory measures are requisite and desirable for power companies that accept social responsibility. As an electricity producer, another critical factor for us – from the perspective of the climate and environment – is to utilize a technology that, in principle, enables the generation of renewable and emissions-free electricity. Global climate change is one of the most important environmental issues of our time, and hydropower can help climate goals to be achieved at both a national and a global level.

Sweden’s energy supply has largely shifted from fossil fuels to hydro and nuclear power, which means that Sweden is now among the OECD countries with the lowest carbon emissions. The global picture differs somewhat with around 80% of the energy used derived from fossil fuels. Furthermore, hydropower is easy to vary, which facilitates the expansion of other forms of intermittent electricity generation, such as renewable wind and solar power. Hydropower is the de facto enabler for the increased presence of other renewable forms of electricity generation within our electricity system. Quite simply, our hydropower plants in Sweden contribute to the attainment of global climate goals.

Hydropower and the environment

Hydropower in the community

Environmental improvement measures around hydropower plants

To prevent and limit the adverse consequences, we work proactively with environmental improvement measures that include research and technological development, and engage in dialog and partnerships with government agencies, as well as environmental organizations and local residents. What is common to all our environmental measures is that they fit within the strategy on environmental measures for hydropower, which was jointly developed by the Swedish Agency for Marine and Water Management and the Swedish Energy Agency.

Find out more

Hydropower has many advantages. It has near-zero emissions of greenhouse gases, while providing a reliable electricity supply at a competitive price. 

We are seeing rising demand for electricity as society develops and new innovations see the light of day. Consequently, balancing power becomes increasingly important, the more solar and wind power we utilize in the electricity system.

With the help electricity, we can replace fossil fuels and drive new innovations. We will thus require more – not less – electricity in the future, in order to resolve climate challenges.

Our global presence

We continue to strengthen our presence in key markets, develop innovative solutions and acquire companies in prioritized areas. Uniper solutions are sold to over 100 countries and we currently operate in over 40 countries.