Mobile and modular power solutions provider Aggreko has signed a ten-year contract with global miner Gold Fields to provide a 25.9 MW hybrid solar and thermal power solution for the Salares Norte openpit gold/silver mine, in Chile.

This solution has been designed to provide power for the entire mine, which sits at an altitude of 4 500 m in the Andes mountain range and is 190 km from the nearest town.

The hybrid system will comprise both tailor-made high-altitude performance diesel gensets and Aggreko solar power units, optimised for off-grid applications and geared for the extreme wind conditions these units will experience.

The gensets will each deliver 772 kW and will incorporate spinning reserve and cold reserve units to efficiently manage peaks in demand.

This diesel generation system will be integrated with solar units, which, once installed, will provide 9.9 MW of cost- and emission-free power.

Aggreko Latin America MD Pablo Varela tells Mining Weekly the solar farm will be split into three smaller farms, as, owing to the higher altitude of the Andes, it is complex to find a single space for the required size farm.

At full capacity, the greenfield Salares Norte project will produce an average of 450 000 oz/y of gold.

The power system will deliver a reliable, modular power supply across all five of the mine’s distribution points, while surpassing the Chilean government’s environmental standards as well as Gold Fields’ requirement for a minimum of 20% renewable power generation for mining operations.

Varela says a hybrid solution is the most suitable, as it will provide the necessary reliability for the mine, is economical and is aligned with Aggreko and Gold Fields’ environmental targets.

The solar farm will provide 100% of the power during high penetration hours, while the diesel can provide 100% of the power the rest of the time, and during the night.

Varela notes that a fully renewable solution is not feasible at present, as the batteries for energy storage are costly, while there is also added complexity for batteries to operate effectively at that altitude.

Once complete, the solution will save Gold Fields $7.4-million in energy costs over the next decade and a further $1.1-million in carbon tax offset over the Aggreko project lifetime in addition to reduction of 104 000 t of carbon emissions.

The modular rental solution also supports a consolidated capital expenditure outlay, allowing for greater cost control and variable commitments while ensuring continued operational excellence at the mine.

The deployment of this hybrid solution follows Aggreko’s recent launch of Aggreko Solar Power, which will be deployed to provide power at the site. This solution is optimised for weak or off-grid energy applications, providing clean and efficient power supply to a range of operations without long-term financial commitments.

Varela says Gold Fields expects the mine to begin operations in 2022, and the power solution will need to be ready to meet this timeline. Aggreko will start construction of the main plant by the end of this year, to be ready to deliver during the second or third quarter of 2022, depending on Gold Fields’ schedule.

After delivery of the main plant, Aggreko will begin with the solar installation, which will take more time owing to the need for environmental approvals. Construction is slated for the start of 2022.

Varela points out that Aggreko is partnering with a local engineering, procurement and construction firm that is knowledgeable about delivering solar farms within the Andes region, with this expertise vital to deploy this solution successfully, owing to the complexities presented by the high altitude and extreme weather on the solar technology.

This is a build and own contract, informs Varela, with Aggreko owning the solution for ten years and Gold Fields having the option to buy it thereafter or return it to the company, depending on the mine’s state in ten years. The mine presently has a life-of-mine of 11 years.

Moreover, Varela acclaims that the contract is flexible, in that it incentivises both companies to continuously seek to achieve improvements. Aggreko can therefore continuously improve the plant over the ten years, as technology improves and allows this, while still providing reliability and commitment to emission reduction.

Varela also highlights that the contract between Aggreko and Gold Fields represents the strong working relationship between the companies, and follows a history of successful collaborations globally.

Moreover, he notes that this contract represents an alignment of both of the companies’ strategies to deliver economically while engendering environmental benefits.

“Importantly, this solution shows that reducing emissions can go together with economic savings, if there is enough trust with the customer to develop the best solution for both sides.

"We spent two years designing the best solution, and this solution represents the best in class, and will continue to evolve over the ten years.”