CANADA-based TransAlta has agreed to build a $A570 million gas-fired power plant to supply Pilbara iron ore miner Fortescue Metals Group and Western Australian utility Horizon Power. TransAlta will build the 150 megawatt power station on Horizon's existing site at the Boodarie industrial estate in South Hedland, Pilbara WA. TransAlta said the 150 megawatt combined cycle gas power plant would be built on Horizon’s existing site at the Boodarie industrial estate in South Hedland and would be one of the most efficient power stations in the region.