Solar Powered Gold
This author no longer works for DNV GL.
Gold is expensive for a reason
The copper in your computer cables, the aluminium in your Coca Cola can, the platinum in your catalytic converter, the gold in your jewellery. How did it get from the earth’s crust to your desk, your fridge, your car or around your neck? Rock was hoisted up from deep underground through many kilometres of tunnels, which are constantly maintained by enormously powerful air and water pumps. Once at the surface, the rocks are pulverized through behemoth grinding machines and then undergo extreme chemical processes involving intense pressure and heat. That all takes energy, but how much?
Consider the element that requires the most energy to extract, gold. In 2014, the gold mining industry is estimated to have consumed 82.83 TWh of electricity, or 82,830,000,000 kWh. That is enough electricity to meet the consumption of a typical United States home for 7.6 million years. In one year of gold mining. And that is just gold.
Africa’s Mining Dilemma
In Africa, many countries are totally dependent on extracting and processing such minerals, even though their national grids are under-developed. This means that in many cases, these operations are totally dependent on diesel fired generators. With mineral prices falling, energy prices increasing and global pressures on supply chains to decarbonize, mining firms need alternative ways to clean up mining, while meeting demand for output and maintaining value to shareholders. For mines that are already financially against the wall, there is an incentive to be ‘first to be second,’ i.e. to implement transitions to their energy supplies, only after it has been shown that solar power is a reliable and affordable alternative. To break this deadlock, there is a need for an independent player. Enter, the Carbon War Room.
Sunshine for Mines
The goal of the ‘Sunshine for Mines’ operation is to rapidly accelerate the installation of renewable energy capacity integrated into the power systems of on-and-off-grid mines around the world. This is done by making it easier, faster and less risky to procure renewable energy from Independent Power Producers (IPP). Carbon War Room has set out to achieve the following ambitious goals:
- By 2018; five major mining companies will establish and implement ambitious renewable energy integration plans with a total of 3 GW installed capacity
- By 2025; the mining industry will reach a 15% renewable energy penetration rate, representing 30 GW of cumulative installed capacity
The first project that Carbon War Room has put DNV GL to work on under the ‘Sunshine for Mines’ programme is a gold mine in Gauteng, South Africa. It is a relatively small mine that processes about 300,000 tonnes of ore each month, but still uses 480 GWh of electricity per year. We visited the mine to appraise the surrounding land for suitability for a large scale solar array to meet the base load of 60 MWp. Solar prospecting at a gold mine felt very 21st Century indeed.
We have now completed a detailed energy assessment of the potential solar yield and are feeding that data into DNV GL’s micro-grid optimization software. This tool has been loaded with a model of the mines electrical systems and the supply tariff and grid characteristics.
In a country like South Africa where the grid is already constrained, anything that can be done to reduce large energy user demands will be a benefit to the whole country. As the national peak of electricity demand often occurs during night time hours, electricity storage systems would allow the mine to store power during the day time for use when their electricity access would otherwise be constrained. Part of the analysis is to simulate long term scenarios of potential grid curtailment and grid failures. There will be a point at which the additional cost of implementing storage makes economic sense compared to the mining operation and production losses from such grid limitations. The micro-grid tool has capabilities to model many storage technologies to identify whether or not this is technically possible, so combined with the economic modelling we will be able to determine whether storage on such a scale is economically and technically viable.
The broader view
Once the study is concluded, an IPP will be appointed by the mine to supply the optimized solution. And bingo; solar powered gold! Next stop will be other gold mines in South Africa, then Chile, Australia and so on, followed by other mineral mines. In time, mines opting for solar to reduce reliance on diesel and electricity from national grids will be standard practise. Carbon War Room will succeed in their goals of decarbonising on a giga-tonne scale and DNV GL will help make mining Safer, Smarter and Greener.
About the Author: Abraham Cambridge is a solar engineer based in DNV GL’s Cape Town office. Abe specialises in large scale distributed solar projects and leads DNV GL’s business development activities for provision of renewable energy and storage services for Southern Africa.