SWEDEN Climate changes can result in major increases in water flows in the rivers used by Vattenfall to generate power. This is confirmed in a new report from SMHI, the Swedish Meteorological and Hydrological Institute.

SMHI has published a new report about Sweden's future climate and the impact it will have on access to drinking water in the country. But the findings can also be used to analyse how the water flows in the power-generating rivers can develop in the future.

"We can already see how the climate in Sweden and the rest of the Nordic region is changing. The average temperature has increased by about one degree in the last 20 years. This confirms climate research that points to a temperature increase in our part of the world more than double the global temperature," says Johan Andreasson from SMHI.

It also means that if the political so-called 2-degree target is reached, then the water cycle in the Nordic region is facing major changes. Researchers have looked at various scenarios and models and even if the results vary somewhat most of them point in the same direction: there will be more water flowing in the northern rivers.

As early as 2010, Vattenfall and SMHI conducted an analysis of the impact the future climate will have on the water flows in the rivers. The findings from the new report augment the conclusions draw back then.
"The climate models and our analysis methods have improved since then, but on the whole they are still very applicable," says Andreasson.

The findings showed then that watercourse flows increase by 14 per cent as an average figure for the various scenarios at the end of the century between 2076 and 2095.

Greater flows produce more power
In 2010 an estimation of how much power could be generated with the anticipated greater flows was also carried out. One of those working with the data then was Per Larsson, who today is Head of Hydro Planning in BA Markets at Vattenfall.
"Back then the average scenario for Sweden was roughly a five per cent inflow increase up until 2050. Our calculations showed that this corresponds to a total hydro power production increase of 2.8 TWh in all of Sweden. One TWh of this increase was to come from the Lule River," says Larsson.

SOURCE: SMHI, Swedish Meteorological and Hydrological Institute

SOURCE: SMHI, Swedish Meteorological and Hydrological Institute

How the water flows in the future will change
The maps show how water flows can change in a scenario with continued intense increases in carbon dioxide emissions. The years 2021 to 2050 are shown on the left and 2068 to 2098 on the right. The colour scale indicates changes compared to today as a percentage.


Major consequences
These water flow changes can have major consequences for a hydro power plant operator like Vattenfall. If a future climate increases the risk of greater flows, then calculations based on the climate of the 20th century can lead to errors, when for instance studying the risk of dam failures.
Claes-Olof Brandesten is Head of Dam Safety at Vattenfall:
"Calculations for a future climate toward the middle or end of the century can indicate future needs which can have an impact on what choice of steps is appropriate to take today," he says.

Investments in 50 year intervals
One other issue for Vattenfall is how to best invest in existing hydro power plants, which is often done at intervals of up to 50 years. Then the flows of the future have a significant role to play as river flow estimations are the basis for how plants must be constructed to utilise the water in the most effective manner.
“To optimise the dimensioning of turbines, generators and transformers, we conduct advanced production analyses where a time frame of up to 50 years clearly falls within the scope of potential climate impact. A well-founded opinion on the future climate is therefore a valuable component in our analysis," says Roger Hugosson, Head of the Production Support unit.

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