Aggreko, a provider of energy services, has completed the installation of a large renewable microgrid at Australia’s Granny Smith gold mine for Gold Fields, the operator of the mine and one of the world’s largest gold miners.
A combination of 7.7 MW of peak solar power and a 2 MW/1 MWh battery system, integrated with Aggreko’s existing 27 MW gas fired power station will meet the site’s electricity demands. The mine’s fuel consumption is expected to drop by 10-13% once the system is fully operational.
“Gold Field’s vision is to be a global leader in sustainable gold mining,” Graeme Ovens, vice president of operations for Gold Fields said.
For the Granny Smith mine, the sustainability journey started when Aggreko worked with Gold Fields to switch the power supply from diesel to gas generation, putting in place a power purchase agreement. As time went on, more gas units were added to meet the mine’s rising energy demands. Further increases in energy demand, as well as decreasing costs of renewables, sparked an investigation into the use of solar and batteries.
“Mine sites in general are not connected to local grids, so they tend to be microgrids,” Ovens explained.
According to the Australian Renewable Energy Agency (ARENA), 35% of mines in Australia are not connected to the grid, and significant proportions are powered by diesel. But mines are under increasing pressure to go green, and there’s an appetite to switch to gas and renewables.
One of the challenges, however, is that compared to gas or diesel generation, switching to renewables come with a high capital cost.
“The mine life, and the length of time we’re able to continue the mining operation, needs to be able to support the investment,” James Koerting, energy manager at Gold Fields, said.
Aggreko’s George Whyte, managing director Australia Pacific, said that using scalable microgrids, similar to this project, allows evolution of the energy system with the mine’s lifecycle.
“Microgrids also offer an independence from grids, that can often result in cost effective solutions,” Whyte explained.
Granny Smith’s share of renewables is currently at 2% and ways to increase this are being investigated.
“We’re not yet done, over the past 12 months we’ve been measuring the wind speed… the results are looking good, there’s a great wind resource,” Rod Saffy, global head of mining at Aggreko said.
Gold Fields and Aggreko plan to use the lessons learned about integrating renewable energy projects with mines at other sites, like Agnew and St Ives in Australia.
In order to achieve sustainability, mines must also tackle the emissions from the diesel powered mining fleet, like trucks and shovels.
“Our ambition is to convert them to a non-diesel energy supply… electricity is probably the best option we’re looking at,” Koerting said.
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