Rio Tinto Ltd plans to invest more than $515 million on...

Rio Tinto Ltd plans to invest more than $515 million on upgrading its power sources in the Pilbara region of Western Australia to support its expanding iron ore operations.

It will build generation and transmission infrastructure near Karratha worth $US503 million to supply electricity to its port and mine operations.

The new power station will be constructed adjacent to the 7 Mile Rail Operations site.

It will use natural gas turbines, resulting in a reduction in greenhouse gas emission rates.

The two steam power stations currently in operation at the Cape Lambert and Dampier ports will be decommissioned.

Rio Tinto will also build a 220 kilovolt power line from the new power station to Cape Lambert.

The power station will be commissioned in 2010.

Company iron ore group chief executive Sam Walsh said the open cycle gas turbines will emit about 25 per cent less carbon dioxide than the existing steam turbines.

"At an annual production rate of 220 million tonnes of iron ore - a rate we expect to reach in Q4 of 2008 - we will be saving 200,000 tonnes a year of greenhouse gas emissions by moving to open cycle turbines," he said.

Rio Tinto is responsible for the generation, transmission and distribution of electricity to its mines, ports and associated towns.