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. We talked to David Manning, Global Head of Hybrid and Arnim Schön, Sales Manager Sub Saharan Africa, from juwi Renewable Energies, about the opportunity.
Typically in the African mining sector, power supply is from fossil fuels, diesel, 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 diesel 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.
What makes hybrid energy an attractive option for mines?
“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 Arnim Schön, juwi sales manager, Sub-Sharan Africa.
Hybrid is now seen as a more attractive solution for mines, because it’s both cost effective and reliable.
juwi’s global head of hybrid, David Manning explains the mining sector’s unique needs: “One of the reasons mines require hybrid energy rather than being entirely dependent on renewables or being entirely dependent on diesel, is that mines operate normally on a 24/7 basis 365 days a year and are very dependent on continuous operations. The startup on a mine site can take several hours, shut down can take several hours and any period of no power is extremely detrimental to operations.”
Schon agrees: “In mines, the stability of power supply is critical. 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.”
“Another advantage of combining renewable energy and battery storage with a grid or fossil fuel power source is the ability to stabilise the grid. With batteries, the reach of renewables expands significantly. Intermittency and weather dependency almost disappear. This means cheaper more reliable and cleaner power for off-takers,” comments Schon.
Renewable energy cheaper than grid supply
With improved technologies and decreasing costs of renewables and storage, the cost of grid supply electricity and renewable energy are generally on a par now. Schon 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, the costs make good sense for mines now: “Mines have been aware of solar and renewable energy, but would mostly look at renewable energy only from a green perspective. Now it is all about saving costs, reducing price and fuel risks while at the same time boosting the social and environmental license to operate.
“With a real trend in reduction of components like storage, we are now in a position where it has become economically viable for a mine to look at this. We can design hybrid plants now that can produce electricity below 10 US cents per hWh in many locations in Africa. I believe this is very attractive for many mines.”
Schon says that in many countries in Sub Saharan Africa grid costs are still fairly high and even 10 US cents would be attractive to many operations.”
Successfully integrating hybrid energy for mines
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 balances 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. This is what juwi excels at.”
An effective monitoring system
At a typical mine site, the mine site operator likes a lot of visibility as to what’s going on with their power supply. It’s very much at the forefront of what mining operators want to see. Manning says that juwi has developed a unique hybrid SCADA system: “It gives our client visibility on all generation assets and enables much greater control and more clarity on power generation costs. The juwi hybrid SCADA combines all power sources and the operator and management can see what’s happening in their power system in real time.
“What we find is once we open up our system to our client and give them good visibility, it gives them comfort and security in knowing they have a reliable supply. It also allows them to track their costs and manage their cost and see where they’re at.”
juwi’s hybrid SCADA seamlessly integrates the control systems from thermal, renewable and plant control. Manning explains: “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. 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.
“To date no one else has successfully operated a large hybrid power plant at a mine for longer and that experience and data enables us to offer mines critical advantages.”
“There are a lot of companies that design thermal power plants or solar or wind systems but there are very few who really understand the needs of mining operations and even less that have the ability to integrate solar or wind with fossil power at a mine site,” says Manning.
Operating in Africa
“juwi has a long history of operating in Africa. Our team built large solar farms in South Africa and Off-grid systems all over the continent. Juwi actually realised the first ever grid-connected solar system in Sub Sahara. This project was built as early as 2007 in Rwanda. We remain committed to providing renewable energy to grow Africa’s economies and power its people,” says Schön.