Image: Gold Fields

A 25.9MW hybrid solar-diesel system is to be delivered by Aggreko to power a new Gold Fields gold mine high in the Chilean Andes.

The system is to be comprised of 9.9MW of solar PV and 16MW of thermal diesel to provide a total of 25.9MW to fully power the new Salares Norte open-pit mine at an altitude of 4,500m in the Andes in northern Chile’s Atacama region.

The location is remote, 190km distant from the nearest town, and the weather conditions are extreme, with high winds and snow commonly experienced.

The solution is designed to meet the rigours of the location with the high altitude performance diesel gensets providing back up to the solar PV and incorporating spinning reserve and cold reserve units to efficiently manage peaks in demand.

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The system, Aggreko’s largest solar PV installation in Latin America, should deliver reliable, modular power supply across all five of the mine’s distribution points. Moreover, it is designed to surpass the Chilean government’s environmental standards as well as Gold Fields’ requirement for a minimum of 20% renewable power generation for its mining operations.

“We worked hard over two years to develop the best solution for the mine with the main requirements being reliability due to the remoteness and being efficient and environmentally friendly,” Pablo Varela, Aggreko’s Latin America Managing Director, told Power Engineering International in an exclusive interview.

“We looked at several options but are limited by the altitude. Diesel is not the most environmentally friendly in terms of emissions but it is within the standards and has other benefits such as being easy to manage and is more efficient than other thermal options. In addition batteries cannot yet work at that altitude due to the impact of the atmospheric pressure on the inverters.”

Varela mentions the mountainous topography of the site as another complexity, which presented an engineering design challenge. With the site use restrictions set by government, the solar arrays will be distributed in three “crazy shaped” locations.

Once complete, the solution is expected to achieve $7.4 million in cost of energy savings over the next decade and a further $1.1 million in carbon tax offset in addition to 104,000 tonnes of carbon emissions savings.

New technologies

The system is being provided under a 10-year rental contract and it is planned to continually evolve it in line with advances in technology.

“We will be looking at technologies such as batteries, not necessarily to shift the generation from day to night as that is still very expensive but to improve the efficiency,” Varela said.

“We don’t know how the system will end up as with the evolution in technologies we may change part or all of the power plant over the next ten years.”

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Aggreko has a long history of collaboration with Gold Fields, one of the most recent projects being one of the world’s largest renewable energy microgrids at the Granny Smith gold mine in Western Australia.

The Salares Norte mine is expected to come into operation in mid-2022, when the full thermal plant also is due to come into operation.