Two solar projects at mines reported more than they delivered, and one delivered exactly as promised

The gap between what mines announce and what they build

A mine that sits far from the shared electricity network generates its own power, usually by burning diesel fuel trucked in at high cost. Solar panels can cut that fuel bill, but the solar capacity a mine announces at launch is not always the capacity that gets built. A megawatt measures how much electricity a power system can generate at once. Two mines in Australia show the gap between announcement and completion from opposite directions, and a third shows what a finished project looks like when it delivers exactly what was promised.

Weipa, a plan cut short

Rio Tinto announced a 6.7 megawatt solar farm at its Weipa bauxite mine in Queensland in 2014, planned in 2 phases. The Australian Renewable Energy Agency, the government body that funded the project, records that only the first 1.7 megawatt phase was ever built. The agency project page states plainly that the project was discontinued on 13 May 2019, and gives no further reason. The 1.7 megawatts built was expected to save up to 600,000 liters of diesel a year. The second phase, which would have brought the total to 6.7 megawatts, was never built.

Agnew, a launch figure and a closing figure

Gold Fields operates the Agnew gold mine in Western Australia on a microgrid, a small independent power system built by EDL that combines solar, wind, a gas engine power station and battery storage instead of connecting to the main electricity grid. When it launched in November 2021, the trade publication RenewEconomy reported it was reaching up to 85% renewable electricity. The funding agency closed its record for the finished project in January 2023, and its own figure is a renewable electricity share of up to 60%, meaning up to 60% of the power used at the mine comes from the sun and wind rather than the gas engine. That is the number used here, because it comes from the record made after the project was finished, not a reading taken soon after the wind and battery stage first switched on in May 2020.

James Harman, chief executive of EDL, the company that built and runs the microgrid, described the day it started working.

Since we completed the microgrid in May 2020, and pulled the switch, it has been powering Gold Fields' Agnew Gold Mine with clean, reliable renewable energy.

James Harman, chief executive of EDL, the company that built and operates the Agnew microgrid. Source 5.

DeGrussa, delivered as planned

Not every project fell short. Sandfire Resources added a 10.6 megawatt solar array and up to 6 megawatts of battery storage to an existing 19 megawatt diesel power station at its DeGrussa copper and gold mine in Western Australia, finished in 2016 in under a year. The system meets up to 90% of the daytime power the mine uses, and saves roughly 5 million liters of diesel every year, cutting carbon dioxide emissions by about 12,000 tonnes annually. The Columbia Center on Sustainable Investment described it as the largest off grid solar and storage facility on a mine site in the world when it opened.

The gap is in the counting

The technology is not what failed at Weipa or Agnew. The solar panels installed at DeGrussa in 2016 are still cutting diesel use a decade later. The gap sits in what gets said at a launch event compared with what a government agency records once a project is finished, or in the Weipa case, discontinued. The second phase planned for Weipa was never built. The renewable electricity share reported when Agnew launched was higher than the figure the funding agency recorded when the project closed. DeGrussa built what it announced, and is still saving diesel today.