The German Hydropower Industry

Hydroelectric power plants can reliably generate electricity at favourable prices over a period of more than 100 years. The high degree of operational and supply security in combination with ever increasing fossil fuel costs make hydropower a cheap and reliable basic source of electricity. Because some types of hydroelectric power plants can store energy and quickly supply electricity on demand, they make a major contribution to grid stability. Hydroelectric power plants reduce dependency on energy imports and their associated risks. In areas without an extensive energy supply system, hydropower can provide the basis for regional economic development.

German companies have been designing, constructing and operating hydroelectric plants for more than one hundred years. This extensive experience forms the basis for the excellent quality of German hydroelectric products worldwide.

Technologies and applications

There are three basic types of hydroelectric power plants: run-of-river, reservoir and pumped storage power plants.

The most common type used worldwide is the run-of-river power plant, also known as a river power plant, which utilises the flow energy of a river. Such plants achieve an efficiency factor of almost 94 % and, as a rule, are used to cover the base load. The plant's capacity is determined by the flow velocity and water level. Some run-of-river power plants can store water when there is a low energy demand, and then use it as reserve water at times of increased demand for electricity.

One particular type of the run-of-river power plant is the diversion hydroelectric power plant. Here, water is dammed by a weir and redirected through a separate intake canal to drive the turbines. With a standard run-of-river power plant there is only a slight difference in altitude between the upper and lower water levels, but a diversion hydroelectric power plant exploits the greater difference in altitude (or higher head) created by the damming.

With a reservoir power plant, the water is stored in a natural or artificial lake and then fed via a penstock to the lower-lying power station. As reservoir power plants function independently of natural water flows, they are ideally suited to balancing out fluctuations in both regional and national electricity production and consumption.

In contrast to the reservoir power plant, a pumped storage power plant uses two water reservoirs to store water, with the greatest possible difference in altitude between the upper and lower reservoirs. If the electricity supply exceeds the electricity demand and there is excess capacity (e. g. at night), the water is pumped from the lower to the upper reservoir. It is stored there until it is required for generating electricity during peak load periods. The generator is driven by impulse turbines, one type of which is the so-called Pelton turbine.