Tjørhom Power Plant is located between the reservoirs Gravatn and Tjørhomvatn, just south of the town of Tjørhom in Sirdal municipality, Vest-Agder county.
Tjørhom Power Plant was part of the third building stage of the Sira-Kvina development, and was completed in 1973. The power plant is linked to the Sira watercourse.
It is located 300 metres into the mountainside and utilises a 158-metre high waterfall. After the water from Gravatn has produced power in the plant, it is led through a 500-metre tunnel to Tjørhomvatn lake and onwards via another tunnel to Ousdalsvatn lake, then through yet another tunnel, this one 18 kilometres long, to the largest power plant in the Sira-Kvina development, Tonstad Power Plant. Two generators with Francis turbines are installed, each with an output of 60 MW.
Skagerak has shares in Tjørhom because at one point, SKK owned the Tjørhom waterfall in the Sira river.
Owners: Lyse Produksjon AS 41.1%, Statkraft 32.1%, Skagerak Kraft AS 14.6%, Agder Energi AS 12.2%