There is no doubt that solar PV is the cheapest form of electricity generation globally. However, how does its application apply to remote mining operations? Africa is blessed with great solar resource, as well as mineral and metal resources – making mining an important industry on the continent. But remotely-located mining operations often mean that energy generation is an important concern.
If a mining operation is located close to a utility grid, there could be an option to commission a new power line or grid connection to the mine. Whilst this may seem like an appealing option, there are many uncertainties in the creation of a new power line, and even in connecting to an existing one. How long will the powerline take to build? How will it be maintained and/or repaired when necessary? What would the costs be of such a connection? These questions need to be asked in conjunction with the political, regulatory and logistical risk considerations in taking on such an intervention. There is also the risk of the existing grid or utility being unreliable with frequent outages.
Another consideration is the risk of using an outmoded form of technology, and what the implications of this might be for the future of your mining operation. Using mobile technology as an example, Africa has been able to leapfrog fixed line telecommunications straight to mobile phones, which has improved livelihoods on the continent substantially. A similar argument can be made for the fixed line electricity grid: decentralised electricity supply enable the opportunity to leapfrog outdated technology and maintenance that comes with fixed power lines to provide decentralised, reliable power.
As such, many mines in Africa do rely on decentralised power, either in the form of diesel or solar PV. In addition to these decentralised power generation sources, battery storage is a great option to reduce costs and risks of power supply.
The most common go-to option for remote mining solutions is diesel generation, due to its portability and reliability for remote mining operations. However, diesel is a costly option. Typically, diesel costs in African gold mining countries are around US$1 per litre of diesel – which translates to US 30c per kWh. This is in comparison to US 5c per kWh of solar PV electricity. Another consideration is the transportation of diesel to the mine site, which ironically is burning diesel to, in turn, burn more diesel. Despite the greenhouse gas emissions implications of this, it also adds an unnecessary layer of costs to the mining operation.
But is there another way? As mentioned above, many remote mines in Africa, whilst distanced to the utility grid and/or high-voltage grid connections, have fantastic solar resource. With the affordability of solar PV solutions, it makes sense to explore a solar PV system for mining operations in Africa. However, to provide power after hours and/or during the early hours of morning or late hours of evening, solar PV needs to be used in conjunction with a backup supply to keep the energy supply consistent. This might take the form of diesel generators, but energy storage – particularly in the form of lithium-ion batteries – is quickly becoming a less risky option. This is, in part, to the falling costs of energy storage technology.
With costs of storage rapidly decreasing, energy storage provides a much more stable cost profile than grid-powered or diesel generated electricity, which both have unknown future cost fluctuations and risks. Similarly, the increased interest in electric vehicles, as well as global uptake of off-grid electricity, have sparked a sharp decline in battery costs.
In addition, battery manufacturing capacity is expected to increase significantly by 2021 from just under 150 GWh/year in 2018 to 350 GWh/year in 2021, with the bulk of manufacturing taking place in China and the US. A similar forecast predicts an increase in manufacturing capacity from 350 GWh/year, to ~700 GWh/year. Similarly, the average battery plant manufacturing size has increased significantly, from around 10 GWh/year to just under 30 GWh/year.
In conjunction with increased global demand and manufacturing capability, the costs of lithium-ion batteries have decreased significantly from 2013 – 2019, from around US$ 446 per kWh in 2013 to US$ 112 per kWh in 2019.
Should the application of a solar PV and battery storage microgrid system be unfeasible for a mining operation, battery storage can still assist mining operations to save money by extending the life of generators by creating spinning reserve. This can create a ~2% diesel saving – or 2 MVA of batteries of spinning reserve could save ~260 000 litres of diesel.
A solar PV and energy storage microgrid ensures the control of power and energy sources. A high concentration of renewable energy, such as solar PV, in conjunction with storage, enables complete control of energy costs, eliminating logistics risks and price fluctuations. There are also various financing options available, such as buying the system outright or entering into a power purchase agreement.
As mentioned, solar PV on the African continent is a no brainer. However, for remote mines, it may be necessary to install solar PV alongside battery storage solutions. Whilst solar PV saves money, energy storage solutions solve a few problems: they provide consistent energy supply and handle load changes, and also ensure that the costs of supplying power to the mining operation are known. This reduces much of the risk of electricity supply for both planned and existing mining operations.