The NWIS - involves five parties that are responsible for generating, distributing and selling energy supplies in the North West region. The parties are: Alinta, BHPBilliton, Pilbara Iron (Rio Tinto), Horizon Power and ATCO Australia.
Horizon Power is the regional electricity utility owned by the Government of Western Australia. Horizon Power is responsible for the operation of the islanded systems in regional WA and for the Corporation's assets attached to the NWIS. Horizon Power has a control centre in Perth, which oversees the operation of the NWIS 24 hours a day. Horizon Power owns approximately 25 per cent of the NWIS and its network interconnects the other networks, which together form the NWIS. Horizon Power purchases its power requirements for the NWIS from ATCO power, APR energy, Pilbara Iron and Alinta Energy.
BHP Billiton owns two transmission lines, one connecting to its Finucane Island facility from Wedgefield and the other connecting to its Yarrie/Nimingarra operations from Goldsworthy. BHP Billiton purchases it power requirements from Alinta.
Alinta Energy owns the generating capacity and transmission interconnectors which supply the power requirements of BHPBilliton. Alinta Energy has two power stations, one at Port Hedland with a capacity of 105 MW and one at Boodarie with a capacity of 70 MW. It is the sole supplier to BHPBilliton.
The 86 MW, gas–fired, Karratha Power Station was developed and built by ATCO Australia (formally ATCO Power) and went into commercial service in 2010. ATCO Australia owns and operates the power station with all electrical output sold through a long term contract to Horizon Power.