The Ruhrverband's lakes were built for water management reasons, either to equalise the water volumes or to purify the river water. An additional effect is the utilisation of the dammed water masses to generate electricity.

All of the barrages in the Ruhr reservoirs are used to generate hydroelectricity. The hydropower plants have a total installed capacity of 28.2 MW, generating an annual average of 92.5 million kWh.

When generating electricity in hydropower plants, both the difference in height between upstream and downstream water and the flow rate play a role. Due to the significantly greater usable height difference, hydropower plants at dams generate more electricity than hydropower plants at reservoirs.

If water is dammed up to ensure the supply of drinking water, the flow rate of dams is reduced and electricity production decreases. If more water is released to create retention space for possible heavy rainfall events or to ensure the minimum discharge, the flow rate increases and electricity production rises.

So-called run-of-river power plants at reservoirs take it as it comes. As much water always flows through the turbines as the river is currently carrying. After rain events, the electricity production of run-of-river power plants therefore generally increases. During long periods of drought, electricity production decreases.

Our teaching material "Electricity from hydropower" for secondary level I clearly explains how electricity is generated from hydropower.