In the context of rising electricity costs and Eskom generation constraints, mining companies should be looking to diversify their energy supply through alternative self-generation technologies such as renewables.

This was the consensus reached by researchers commissioned by the Mandela Mining Precinct and tasked to develop, through directed research and development, an energy efficiency guideline for the industry.

“Through this research theme, we are investigating current systems in the industry, with the aim to structure alternative energy sources and optimise energy supply strategies, and efficient energy utilisation,” said Mandela Mining Precinct programme manager, Martin Pretorius at a virtual workshop held on 17 September 2020. Pretorius is responsible for the Mechanised Mining Systems research programme, which focuses on developing solutions that will lead to the increase of economically feasible platinum and gold orebodies through new approaches.

This research theme is led by the University of Pretoria (UP) Centre for New Energy Systems (CNES) senior lecturer, Dr Xianming Ye. Ye emphasized that this study focuses on both the financial and technical viability of renewable energy options available to the industry.

“South Africa has been experiencing rapidly rising electricity costs since 2008, which have been difficult to absorb for many mining operations. The 2019 Integrated Resource Plan indicates that the cost of electricity will continue to increase in real terms up to 2050, as the aging coal fleet is replaced with new generation capacity,” said CSIR senior researcher, Dr Peter Klein. Klein highlighted that in this context of rising grid electricity prices, the costs of renewables such as wind and solar photovoltaics (PV) will continue to decline, which presents new opportunities for industrial users to consider embedded generation. The roll out of a customer response at scale can also significantly reduce the levels of load shedding. However, going off-grid is currently cost prohibitive, and an optimal solution will likely include a mix of grid electricity, supplemented with embedded generation.

However, the researchers found that there is some good news. Climate models indicate a good solar source in the gold and platinum mining regions of South Africa. Klein said there were three primary options available to utilising the solar source. Electricity can be generated using PV technologies; concentrated solar power (CSP), which converts solar energy into heat using concentrating collectors to drive a steam turbine and produce electricity; and the third option is to use solar thermal systems to generate heat for industrial process heating.

Conversely, in terms of wind, Klein explained that there is a poor resource in the identified mining regions. However, there is a good wind resource in an area of the North-West, which is within a 100 km proximity to many mines. From a technical and financial perspective, Klein explained that a mix of solar and wind provides the least cost mix of electricity due to the complementary nature of the solar and wind sources, and decreasing costs of these technologies. These energy sources can be supplemented with gas, biomass, CSP, demand-side management, and energy storage.

While Klein said that energy storage systems could be used to absorb the variabilities offered by solar and wind, Dr Farshad Barzegar also from the UP CNES, explained that there were several energy storage options available, offering various lifetimes and capacities that must be taken into consideration in line with energy demand.

South Africa’s current energy mix is dominated by coal, representing 71% of the total energy mix. South African Weather Service researcher, Dr Henerica Tazvinga, indicated that, by 2030, the energy mix would likely look very different. Coal is expected to represent only 43%, followed by wind, which will see a stark increase from currently representing only 4% of the energy mix; to 23% by 2030.

The research team, representing a number of universities and science councils, are working closely with industry experts to ensure that the framework and guideline delivered through this study, will gain industry support and uptake, said Pretorius.

The Mandela Mining Precinct is a public-private partnership between the Department of Science and Innovation and the Minerals Council South Africa. The Precinct is proudly managed and hosted by the CSIR.