Modern Mining June 2018

POWER SUPPLY AND ENERGY EFFICIENCY

With the promise of significant cost savings and security of power supply in unreliable grid and remote off-grid regions, the African mining sector is putting hybrid renewable energy solutions firmly on the agenda. This is the view of David Manning, Global Head of Hybrid, and Arnim Schön, Sales Manager Sub Saharan Africa, from juwi Renewable Energies. Hybrid power solutions now competitive for Africa’s mines

T ypically in the African mining sector, power supply is from fos- sil fuels, diesel or HFO (heavy fuel oil) and is often off-grid because of the remote location of mine sites. Traditionally, diesel and HFO have been the primary supply of energy in off-grid areas. However, transporting fuel to remote areas is difficult, expensive and carries risk – both from a commercial and environmental perspective. With the development of hybrid power solu- tions at competitive costs, mines are now look- ing at the alternatives. “In mining, the electricity costs are gener- ally around 20-30 % of the operational costs. So reducing power costs will obviously have a big impact on the bottom line of a mine. Renewable energy has not always been viewed positively by mines; now it makes economic sense, because the price of renewable energy has come down significantly,” says Schön. He adds that stability of power supply is critical for mining operations. “A mine cannot afford any losses or cuts in power. This would have a major impact on the operation and to

restart a process plant or mill can take up to a day – production losses could be very high.” Historically mines were hesitant to look at pure renewable solutions which were daylight and weather dependent. “Hybrid bridges the gap; it allows mines to run renewables when the sun shines, and when there is wind, but to fall back on diesel and battery storage for reli- ability,” says Manning. “And as battery technology is becoming cheaper, we are seeing more installations where batteries are viable. Batteries enable larger solar or wind systems and enable mines to transition seamlessly from renewable energy across to diesel without interruption to supply.” With improved technologies and decreas- ing costs of renewables and storage, the costs of grid supply electricity and renewable energy are generally on a par now. Schön explains the implications: “What we’re able to do is put a renewable/hybrid solution behind the grid at equal or less cost, with added reliability and consistency in supply. In many instances, renewable energy is significantly cheaper than grid supply, so we’re able to offer a cheaper and

The concentrator at the DeGrussa gold and copper mine of Sandfire Resources in Western Australia. A 10,6 MW solar facility at the mine comprising approxi- mately 34 000 solar panels was commissioned in 2016. The panels are connected to a lithium-iron battery stor- age facility and the existing diesel-powered power station at DeGrussa. juwi was one of the participants in the project.

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June 2018  MODERN MINING  31