The increase in the establishment of micro- and mini-grids at mining operations has been driven by the need to be independent from the national grid and to reduce environmental impact, writes Dr Nicolaas C Steenkamp.
Driving along mining operations in recent years, observers will have noted an increasing number of solar projects at mining operations. Regions like South Africa, and increasingly southern Africa, have seen an uptick in the number of mining operations that have opted to either meet their energy needs by establishing infrastructure that will reduce their dependence on an increasingly unreliable and unstable national grid, or to become fully self sufficient in generating their energy needs. The significant amount of sunny days in southern Africa have made photovoltaic (PV) installations the preferred method of power generation for mining operations that have large tracts of surface area at their disposal.
Two types of grids are employed by the mining operations. One type is micro-grids that were initially installed to overcome loadshedding specifically as well as supply interruptions that have increasingly affected the sector over the last decade. These micro-grids are designed to offer a readily available backup source of power and a more cost-effective solution to running expensive diesel generators to maintain operation.
A combination of the increasing efficiency of especially PV panels, better energy storage and batteries over the last couple of years and cost considerations, have led to more mining operations investing in the development of their own private mini-grid, the other type. These mini-grids are capable of generating and storing sufficient power to ensure that the mining operations always have sufficient spinning reserves to have all mining and mineral processing equipment and plant operational. The PV installations are also considered to be a green solution for power utilisation by mining operations, that count towards better ESG gradings and rating lower carbon emissions scores.
The main considerations when installing a micro- or mini-grid for operational purposes is the intended utilisation, as either a backup system or as the primary power supply. The mining operation would need to have sufficient surface area available for the PV installation to generate sufficient power. This would then be followed by survey and digital surface mapping of high enough resolution to detect 0.5m changes in the surface. The next step is to undertake a detailed geotechnical investigation to determine the anchoring requirements and depths. The energy storage capacity is considered, where the batteries are required to be able to charge fast enough to capture the energy generated and have sufficient capacity to support full operational requirements during the times when less or no energy is generated. The batteries would also need to be low maintenance and since a significant number of these installations are far from urban areas or other specialist maintenance services, the system needs to be capable of being fully remotely monitored and ideally integrated into the operational IoT at the site.
The current limitation however still remains the high initial capital investment needed to install the micro- and mini-grid networks – the main cost factor being the cost of the batteries and the capped life-of-operation in terms of the number of deep recharge cycles it can handle. Current battery systems are also not yet capable of fully meeting the power demand to the extent that current diesel generators are able to produce. The cost of diesel and increasing supply uncertainty is however expected to become a consideration in future.
Mini- and micro-grids that operate off natural energy sources, such as solar, hydro and wind, are considered to be a green power source. Installation and operation of these grids therefore count towards a more positive ESG score for mining operations. The systems are considered sustainable as they lower the scope 1, scope 2 and scope 3 carbon emissions from these operations over the life-of-mine. Making any surplus generation capacity available to support community upliftment projects, specifically targeting small-scale production and job creation initiatives, further increase social responsibility ratings.
A number of studies are also underway to determine the extent to which mini-grids can be established as part of a just transition away from fossil fuel generation of power. The areas that will be affected by the shutdown of coal-burning power stations in the coming years will need alternative means of supporting the communities. The viability of installing solar panels and wind turbines on these sites is being investigated.
As renewable and green energy generation and storage systems improve and the cost of installing and operating these systems decrease, the potential for further adoption of it by the mining industry is increasingly likely. It is also hoped that specifically in South Africa, the easing of legislation for the production of independent power and supplying or supporting the national grid will result in better energy security for the nation and the industrial and mining sectors. Developments in this regard are sure to be closely monitored in the near future.
Dr Nicolaas C Steenkamp is an independent consultant, specialising in geological, geotechnical and geometallurgical projects and mining project management. He has over two decades of industry experience with global exposure. firstname.lastname@example.org