Hammeren Hydroelectric Power Station is a hydroelectric

Hydroelectricity

Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...

 power station

Power station

A power station is an industrial facility for the generation of electric energy....

 located in Oslo

Oslo

Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...

, Norway. It is the only power station in Oslo, and among the oldest power stations still running in Norway. It has a total installed capacity of 5 MW, and an annual prodcution of 16 GWh. The powerstation utilises the waterfalls from Skjærsjøen

Skjærsjøen

Skjærsjøen is a regulated lake in Nordmarka, Oslo, Norway. It drains through the river Skjærsjøelva to Maridalsvannet, and also via tubes to the Hammeren Hydroelectric Power Station. It is regulated by the dam Skjærsjødammen from 1890.-References:...

 to Maridalsvannet

Maridalsvannet

Maridalsvannet is a lake in Maridalen, Oslo, Norway. It is the largest lake in the municipitality of Oslo, and serves as the main drinking water supply for the city. The lake drains via the river Akerselva to the Oslofjord. The primary inflows are Skjærsjøelva and Dausjøelva. The Hammeren...

, with a total height of 105 m. It was established in 1900 by the company Christiania Elektricitetsværk, originally with 4 generator units, and increased to six units in 1901. In 1927 the six generators were replaced by a single 5.6 MW unit.