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With electricity costs on the increase, and power utility Eskom experiencing ongoing constraints, mining companies should be looking to diversify their energy supply through alternative self-generation technologies such as renewables.

This is the view of researchers who have been commissioned by the Mandela Mining Precinct to develop, through directed research and development, an energy-efficiency guideline for South Africa's mining industry.

Mandela Mining Precinct programme manager Martin Pretorius, speaking at a virtual workshop on 17 September, said the research team was investigating current systems in the industry "with the aim of structuring alternative energy sources and optimising energy supply strategies for efficient energy utilisation".

Pretorius added that the team, representing a number of universities and science councils, was working closely with industry experts to ensure that the resulting framework and guideline gained industry support and uptake.

The research theme is led by Dr Xianming Ye, senior lecturer at the University of Pretoria's Centre for New Energy Systems. Ye, also speaking at the workshop, said the study focused on both the financial and technical viability of renewable energy options available to the industry.

Dr Peter Klein, an energy expert from the Council for Scientific and Industrial Research (CSIR), noted that South Africa had been experiencing rapidly rising electricity costs since 2008, and that these had 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 ageing coal fleet is replaced with new generation capacity."

While grid electricity prices continued to rise, Klein said, the costs of renewables such as wind and solar photovoltaic (PV) energy would continue to decline, presenting new opportunities for industrial users to consider embedded generation – i.e. to consider producing on-site, on a small scale, their own electricity.

However, as going off-grid was currently cost-prohibitive, an optimal solution would likely include a mix of grid electricity supplemented with embedded generation using renewable sources.

Regarding the availability of renewables for self-generation, Klein said that climate models indicated the presence of good solar resources in South Africa's gold and platinum mining regions. Regarding wind power, while there were poor resources in the identified mining regions, a good wind resource existed in an area of the North West that was within 100 kilometres of a number of mines.

Klein explained that there were three main options for generating power using solar sources. This could be done through solar PV technology; through concentrated solar power (CSP) technology, which converts solar energy into heat using concentrating collectors to drive a steam turbine and thereby produce electricity; or through solar thermal systems that generate heat for industrial process heating.

From a technical and financial perspective, Klein said that a mix of solar and wind offered the most cost-effective mix, due to the complementary nature of solar and wind sources and the decreasing costs of the associated technologies. Solar and wind could also be supplemented with gas and biomass, while energy storage systems, together with demand-side management, could be used to offset the variabilities of solar and wind.

Dr Farshad Barzegar, also from the Centre for New Energy Systems, said that a number of energy storage options were available, offering various lifetimes and capacities, that should be considered in line with energy demand.

Dr Henerica Tazvinga, a researcher at the South African Weather Service, said South Africa's energy mix would look very different by 2030. Coal, which currently accounts for 71% of the total mix, is expected to represent only 43% by 2030, followed by wind, which is expected to increase sharply from its current 4% to 23% of the energy mix.

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 managed and hosted by the CSIR.

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