Every Smelting Plant in the world must have its own Power Plant and so must PT INALUM (Persero). PT INALUM (Persero) owns a Hydroelectric Power Plant which is located along Asahan River, the only river flowing Lake Toba water to Malacca Strait. PT INALUM (Persero) owns three dams. The first one is Regulating Dam in Siruar, around 14.5 KM from Lake Toba. It is to regulate water to be used at Siguragura Power Station. The second dam is Siguragura Intake Dam at Simorea, 9 KM downstream of Regulating Dam. It is to create necessary head to produce power at Siguragura Power Station. Siguragura Power Station is located 200 m underground. The power station is installed with 4 units of generator with 286 MW of each capacity. The third dam is Tangga Intake Dam at Tangga, 4 KM downstream Siguragura Power Station. It is to create necessary head to produce power at Tangga Power Station. Tangga Power Station is installed with 4 units of generator with 317 MW of each capacity.
Inalum Regulating Dam is located in Siruar, around 14.5 km downstream of Lake Toba. It is to regulate water level of Lake Toba and water flow from Lake Toba to Asahan River for constant water supply to Inalum Power Plants.
The type of the dam is concrete gravity with 39 meter high.
Siguragura Intake Dam is located in Simorea and to supply stable water to Siguragura Power Station. Siguragura Power Station is located 200 m underground. It has 4 units of generator, and total firmed power generated is 203 MW. It is the first underground Power Station in Indonesia.
The type of the dam is concrete gravity with 47 m high.
Tangga Intake Dam is located in Tangga and to dam water which has been used from Siguragura Power Station and flow the water to Tangga Power Station. It is the first arch-shape dam in Indonesia. Tangga Power Station has 4 units of Generator. Total firmed capacity of those four generators are 223 MW.
The type of the dam is concrete-arch dam with 82 m high.
The power produced by 2 (two) power plants of PT INALUM (Persero) is then transmitted to the Aluminium Smelter in Kuala Tanjung through 271 units of 275 KV Transmission Lines, 120 km long.
Through Inalum substation in Kuala Tanjung, the power is then distributed to three reduction buildings and other facilities through 2 units of Silicon Rectifier of DC 37 KV and 800 V.
Carbon Plant which produces anode blocks consists of Anode Green Plant, Anode baking Plant, and Anode Rodding Plant. At Anode Green Plant, coke and hard pitch are mixed and formed into an anode block and baked up to temperature of 1,250 degrees Celcius at Anode Baking Plant. Then at Rodding Plant, a rod is attached to the baked anode block by molten cast iron. Anode Block functions as an electrode in the Reduction Pot.