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.
Solar panels at the Mulilo Sonnedix Prieska PV solar park in South Africa's Northern Cape Province - engineering, procurement and construction by juwi.
Typically in the African mining sector, power supply is from fossil 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 solutions at competitive costs, mines are now looking at the alternatives.
“In mining, the electricity costs are generally 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 reliability,” 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 decreasing 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 more reliable solution compared to the grid.”
According to Schön, juwi can design hybrid plants that can produce electricity below 10 US cents per kWh in many locations in Africa.
Reliable and robust integration of solar or wind into diesel or HFO power stations at mines is a key success factor. Therefore juwi has developed hybrid technology and solutions that enable seamless integration of various power sources.
Manning explains: “What we call the hybrid controller is the heart of the operation and designing and implementing it properly is of paramount importance. Juwi has put a lot of engineering and development into that process, ensuring that all sources in the power system work seamlessly and balance solar, diesel, wind or battery so that there is zero interruption to supply. It is all about maintaining voltage, frequency and power factor no matter if the sun shines, the wind blows or a large mill ramps up.”
Juwi has developed a SCADA that seamlessly integrates the components of hybrid renewable energy solutions. “What we found is that other systems provide only separated views or systems; one for solar, one for diesel and maybe wind and battery, but not integrated properly and with high resolution,” states Manning. “What the juwi hybrid SCADA does is bring it all together into one system that monitors and combines everything and gives the operator easy access.”
The juwi Group was established in 1996 in Germany. juwi Renewable Energies based in Cape Town (juwi South Africa) is participating in the Renewable Energy IPP (REIPP) Procurement Programme initiated by the South African government for utility-scale renewable energy power generation. To date, juwi South Africa has built five solar plants totalling 121 MW under the REIPP Procurement Programme.
