INALUM constructed and has been operating a power plant consisting of Sigura-gura and Tangga Power Stations known as the Asahan No. 2 located in Paritohan, Toba Samosir Regency, North Sumatra Province. The two power stations are operated by using water of Asahan River which flows from Lake Toba to the Malacca Strait.

2. Aluminium Smelter

INALUM built the aluminium smelter and its ancillary facilities on the area of 200 ha in Kuala Tanjung, Sei Suka District, Batu Bara Regency (formerly Asahan), about 110 km from Medan, the capital city of North Sumatra Province.

The smelter with the capacity of 225,000 tons primary aluminium ingot per year was constructed facing the Malacca Strait. The construction of Smelter was commenced on July 6, 1979 and the first stage of its operation was on January 20, 1982. It was inaugurated by President of Republic of Indonesia, Soeharto in a ceremony attended by 12 Ministers of Pembangunan II Cabinet. The operation of the first pot was on February 15, 1982 and in March of the same year, the first aluminium ingot was successfully cast.

On October 14, 1982, the Ocean Prima loaded 4,800 tons of Aluminium Ingot left Kuala Tanjung for Japan marking the export of INALUM ingot product. This also made Indonesia recognized as one of the aluminium exporting countries in the world.

One millionth ton production of aluminium ingot was reached on February February 8, 1988, the second millionth ton was on June 2, 1993 and on December 12, 1997 the third millionth ton of ingot was produced. The fourth millionth ton was reached on December 16, 2003. And the five millionth ton was produced on January 11, 2008.

INALUM's product becomes an export commodity mainly to Japan and it is also for domestic producers use the ingot was raw materials for aluminium downstream industry such as extrusion, cable and aluminium sheet. The product grades are 99.70%, and 99.90% of aluminium purity.

INALUM's smelter at Kuala Tanjung is concerned with smelting process of alumina to produce primary aluminium metal using alumina, carbon and electric energy as main ingredients. The smelter has three main processing plants namely Carbon Plant, Reduction Plant, and Cast House and other supporting facilities.