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General information - Hydropower


In pre-industrial times hydropower was used to operate mills, saw mills and hammer mills. Turbines convert the kinetic and potential energy of a water flow into mechanical rotation energy which can be used to drive machines or generators. In Germany today, hydropower is almost exclusively used to generate electricity.

Position of hydropower in energy generation

Hydropower is a mature technology. Worldwide hydropower accounts for the second largest share of renewable energy, second only to traditional biomass utilisation. 16% of all electricity generated globally comes from hydroelectric power stations!

At the end of 2006, about 7,300 small hydroelectric power stations (< 1,000 kilowatt = 1 megawatt) were in operation in Germany, generating approx. 8–10% of all hydroelectricity. The remaining share comes from 354 medium-sized or large plants. Only 12% of the plants are owned by energy utilities, but these generate more than 90% of all hydroelectricity. The overall installed capacity is about 4,720 megawatts, of which 700 MW must be considered non-domestic since they come from hydroelectric plants located on the border.

In Germany in 2007 approx. 20.7 billion kilowatt hours of hydroelectricity were generated. This accounts for a 3.4% share in electricity generation, a 23.6% share in electricity generation from renewable energy sources and a reduction of CO2 emissions by 22.6 million tonnes.

The future role of hydropower

Germany’s southern Länder have the largest hydropower potential as the Alpine foothills provide a favourable slope of terrain. Replacement, modernisation and reactivation of existing plants and new construction in existing transverse structures constitute a major potential for hydropower. In all cases balanced consideration of environmental impacts must be taken into account. The German government’s goal is to increase the output whilst improving ecological water parameters at the same time. Due to the incentives for investment under the EEG a modernisation of larger plants can be expected for the years to come.

Revision of water law

On 1 March 2010 the revised water law will enter into force. The extension of provisions on the management of surface water bodies is particularly relevant for the use of hydropower. Pursuant to Article 33 of the Federal Water Act, damming, abstracting or diverting water is only admissible if a sufficient minimum water flow is guaranteed. Article 34 of the Federal Water Act stipulates that the construction, substantial modification or operation of a dam is only admissible if the continuity of the water body is maintained or restored where this is necessary to achieve the management goals. Article 35 of the Federal Water Act specifies the ecological requirements for hydroelectric power plants. They may only be operated if adequate measures for the protection of the fish population are taken. This was done to ensure that fish may pass hydroelectric power plants unharmed during migration.

Types of hydroelectric power stations

The basic distinction is between smaller (smaller than 1 MW) and larger stations (larger than 1 MW). 20% of the large power stations in Germany are storage power stations, 80% are run-of-river plants.

  • Smaller hydroelectric power stations

    There is a certain expansion potential for small hydroelectric plants, in particular through modernisation and reactivation of existing plants or in some cases through the construction of new transverse structures which become economically viable due to the Renewable Energy Sources Act (EEG). In this context nature protection and water ecology issues must be taken into account. These plants are either stand-alone operations or grid-connected. Technically they are either pumped storage plants or run-of-river plants; due to smaller fall heads and water volumes their power output is lower.

    Standard investment in the construction of new smaller hydroelectric power stations with a capacity range of 100 to 1,000 kW varies between 4,000 and 6,000 €/kW. Electricity production costs are between 10 and 23 cent/kWh in the case of standard capacity utilisation of 3,000 to 5,000 full load hours per year. Construction costs for hydroelectric power stations are linked to the installed capacity. However, they are also influenced by the water level difference, other on-site conditions and in particular ecological measures that may be needed.
  • Storage power stations

    Storage power stations use the high gradient and the storage capacity of reservoirs and mountain lakes for electricity generation. In barrage power plants turbines are located at the foot of the dam wall. In pumped mountain power stations delivery mains connect a high-altitude lake with a hydroelectric power station in a valley. Pumped storage plants can be used to meet base load requirements or to cover peak operation requirements.

    Pumped storage plants use water pumped up from a valley rather than natural water reserves. Electricity generated at times of low demand may thus be stored for an interim period as potential water energy and be released again in peak hours via a turbine.

  • Run-of-river plants
    Run-of-river plants use the current of a river or a canal for electricity generation. A low fall head and relatively large water volumes which fluctuate considerably with the seasons are a typical feature. For economic reasons these stations are often built alongside locks.


Many German companies specialised in such power stations are also very active abroad. Equally, companies from Austria, Switzerland, France, the Czech Republic and Poland are active on the German market. It is therefore difficult to estimate job impacts. Latest estimates show that in Germany in 2007 approx. 9,400 people were employed in the hydropower sector which generated a total turnover of €1.23 billion.

Wassertropfen (Foto: H.-G. Oed)

Further Information:

Legislation on hydropower