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How Gold Fields' Agnew Mine will move from 54% renewables to 99% - Energy and Mines

Wednesday, 26 August 2020

How Gold Fields’ Agnew Mine In Western Australia Will Move From 54% Renewables To 99%

Gold Fields, the South Africa-based gold mining company, pioneered a mix of solar, wind, battery storage, and back-up gas generation at its Agnew mine near Leinster, Western Australia. This hybrid system, commissioned in May, is now stable with renewables providing a 54% share on average annually.

James Koerting, Gold Field Australia’s manager of electrical operations, said Tuesday that the miner had now set its sights on a renewables fraction target of 99%, according to RENEW ECONOMY.

However, the main stumbling blocks remain the low-cost thermal power component and the nonavailability of synthetic inertia from its battery storage system. Agnew, therefore, needs to run two thermal engines continuously at half load to meet the synthetic inertia threshold.

This thermal generation leads to the curtailment of renewable energy, reducing its overall share in the power mix.

Koerting’s proposal: Lift the constraint by using another form of inertia and utilize the curtailed energy to drive up the renewable fraction.

Regarding inertia, the possible solutions include batteries capable of synthetic inertia or the integration of a synchronous condenser or a flywheel.

However, energy storage is the next technology frontier for decarbonization according to Koerting. Whatever its form, the bottom line is that it must match the marginal cost of thermal generation.


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