Longerak power station lies in Bygland Municipality. It was built by the central government in 1915 and started supplying the Landeskogen sanatorium with electricity the following year.
The power station lies half way up the valley side on the east side of Lake Byglandsfjorden. The power station makes use of the 300-metre drop from Longeraksvatnet reservoir, which is dammed to an elevation of between 598 and 594 m a.s.l.
Longerak power station supplies Agder Energi with 7 GWh of renewable energy per year, making it our 40th biggest power station.