Ground-breaking solar microgrid completed at Granny Smith gold mine

A ground-breaking hybrid solar and battery microgrid built to help power a gold mine in remote Western Australia has been completed and is cutting the mine’s fossil fuel consumption by up to 13 per cent.

The 8MW solar and 2MW/1MWh battery system was designed by energy services company Aggreko and integrated with the existing 27MW natural gas power plant at the Granny Smith mine in partnership the mine’s owner, Gold Fields.

Aggreko and Gold Fields said this week in a statement that the now completed microgrid – that is, the solar, thermal and battery storage combined – would produce around 18GWh of energy every year.

The system is managed by Aggreko’s software platform and uses the Younicos lithium-ion battery not for storage of excess solar but to provide essential “smoothing” services such as PV ramp rate control and transient voltage/frequency support.

And while the solar supplies only a small percentage of the mine’s needs – an average of between 10-13% – it has been an important starting point for Gold Fields’ company-wide strategy to source power from renewables whenever and wherever possible.

Indeed, the Granny Smith microgrid marks the first large-scale renewable energy project that Gold Fields has completed anywhere in the world.

“Gold Fields vision is to be a global leader in sustainable gold mining, and we started this journey many years back,” said Graeme Ovens, Golf Fields’ vice president of operations in Australia, in a webinar on Wednesday evening. “And we started with Granny Smith.

For that mine, an underground operation located 740km northeast of Perth and around one hour’s drive from the nearest town, Gold Fields first stop was to switch from diesel to gas generation back in 2015.

But as the mine’s energy needs continued to grow, says Ovens, “we looked and we said, ok, we need to do something better than just gas.”

Having added solar and a battery, the team is now also considering the addition of wind power to the microgrid, to increase the mine’s share of renewables.

James Koerting, Gold Fields Australia’s unit manager of electrical operations, said working with Aggreko on the Granny Smith project had given the miner the confidence to shift to renewables on other projects, too – including the Agnew mine in Leinster, W.A. it has been working on with EDL.

“This project’s really helped us to learn what we needed to do to invest in renewables, and we’re going to continue to do that to the point where renewables are now business as usual for Gold Fields.”

Aggreko’s managing director for Australia Pacific operations, George Whyte, said demand for decentralised and renewable energy solutions had skyrocketed over the past few years in the mining sector.

“From our point of view,” Whyte told the webinar on Wednesday night, “we feel it is still very ground-breaking, and it’s the future of mining.

“Hybrid energy systems that combine conventional power with renewable energy or battery storage are fast becoming the obvious choice for mines.

“We’re pleased to have completed the installation of one of the world’s largest microgrids and look forward to continuing to partner with Gold Fields to deliver greener, cheaper and more efficient power for the Granny Smith mine in the years to come,”  Whyte added in a written statement.