"We are fast sharing lessons from this project with our other regions, as part of our global strategic initiatives to improve our security of supply and reduce carbon emissions," Gold Fields Australia executive vice-president Stuart Mathews said this week.

Mathews said the under-construction microgrid at the Agnew gold mine featured five wind turbines able to deliver 18MW of power, a 10,000-panel solar farm contributing 4MW, a 13MW/4MWh battery energy storage system (BESS), and a 16MW gas engine power station. The latter would "underpin supply when required". Renewable power is expected to contribute up to 60% of Agnew's energy needs.

The microgrid will be owned and operated by international energy group EDL, which has a 10-year electricity supply agreement with Gold Fields. The Australian Government-backed Australian Renewable Energy Agency (ARENA) is contributing a "recoupable" A$13.5 million to its construction.

Mathews said Gold Fields was making staged investments at four mines in WA to "significantly ramp up the innovative use of renewables to meet our dynamic and growing load requirements". The company expects to complete installation of 20,000 solar panels and a 2MW/1MWh battery system at the Granny Smith gold mine in the December quarter this year.

ARENA CEO Darren Miller said the Agnew project would provide a "blueprint for other companies to deploy similar offgrid energy solutions and demonstrate a pathway for commercialisation, helping to decarbonise the mining and resources sector".

Mathews said monitoring instrumentation that would detect approaching cloud cover for solar and, potentially in the future, detect changes in wind velocity, would be used to help schedule gas generator activation.