Hydroelectric Power

Blue and Green: Reliable and Climate-Friendly Hydropower


Hydropower is one of the oldest renewables. For centuries people have used water to drive pumps and water wheels. The world’s first hydroelectric station opened in the nineteenth century. With around 2 GW of installed capacity, we’re one of the largest hydro operators in Germany. We also have 1.5 GW of hydro capacity in Sweden, which has one of the smallest carbon footprints of any industrial country

The energy transition makes this established energy resource more relevant than ever. Wind and solar power are experiencing rapid growth. But both are highly intermittent due to fluctuating weather conditions. By contrast, hydropower is reliable enough to provide baseload power. It’s also flexible and can be used to store large amounts of energy. Hydroelectric stations can jump-start the grid after a widespread outage.

Hydro power at Lake Eder

Interview with Dr. Klaus Engels

Hydropower is an established technology, which makes it a great partner for wind and solar energy. Hydropower has been the mainstay of Sweden’s energy supply for decades. It plays a smaller but still important role in Germany’s energy supply. Pumped-storage plants in particular balance out fluctuations in renewables output, stabilize the grid, and promote a successful energy transition.

Dr. Klaus Engels, Director Operations Hydro Germany

Every kilowatt-hour of hydropower is nearly zero carbon.


Roundtrip flights from Frankfurt to Sydney

That’s how much carbon our hydroelectric stations in Germany can displace each year (based on Germany’s current energy mix; 12.46 metric tons per flight).

Our operations in Germany

In Germany alone we operate 108 hydroelectric stations (run-of-river, reservoir, and pumped-storage stations) along more than 1,000 kilometers of the Lech, Isar, Donau, and Main rivers in southeast Germany. We also have a plant on Lake Eder, one of Germany’s largest artificial lakes.

The responsibility for operating these assets safely and economically is assigned by river system, giving us four river groups. Their job is to prevent flooding and environmental damage. They also work closely with stakeholders ranging from political leaders (mayors, county commissioners, members of parliament) to nature conservation associations and other NGOs.

Unlike other renewables, hydro is flexible and can store energy.

But how does it work?

Some hydro assets, called pumped-storage hydroelectric (PSH) stations, can switch quickly between electricity production and storage. They can store energy by using surplus electricity in the grid to pump water into a reservoir at a higher elevation. When energy is needed, the water is released to drive turbines that produce electricity. This enables them to balance out load fluctuations and regulate grid voltage and frequency. They therefore play a crucial role in ensuring grid stability and in integrating intermittent wind and solar output. They can also be used to jump-start the grid after a widespread outage.

PSH stations have a round-trip energy efficiency of between 70 and 80%. This means that 70 to 80% of the energy used to pump the water higher is recaptured when it falls. They currently represent the only technology capable of efficiently storing large amounts of energy for an extended period.



Availability rate of our German run-of-river and reservoir hydroelectric stations.

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