New Zealand's Aluminium Smelter (NZAS) is New Zealand's only aluminium smelter and is located on Tiwai Peninsula, across the harbour from Bluff in Southland. NZAS is 79.36 per cent owned by Pacific Aluminium and 20.64 per cent owned by Japan's Sumitomo Chemical Company. NZAS is a tolling plant, producing primary aluminium in the form of ingot, billet and rolling block. The majority of the plant's alumina is supplied from refineries in Queensland and Western Australia. Around 90 per cent of the aluminium produced at NZAS is exported. In the 1960s, Tiwai Point was chosen as the location for an aluminium smelter for a number of reasons. Aluminium smelting requires a large and very reliable power source to continually supply electricity to reduction cells, and Tiwai Point's proximity to the then proposed Manapouri Power Station made it an attractive location. In addition, Tiwai Point was close to the deep sea port of Bluff and the well established infrastructure of the City of Invercargill. The smelter commenced operations in 1971. NZAS contributes $525 million to the Southland economy (10.5 per cent of Southland's GDP) and $1,600 million in Southland regional sales, with export revenue of around $1 billion each year. Approximately 800 full time equivalent employees and contractors work at the smelter.