Integrating renewable power after construction in mining operations aims to enhance efficiency and decrease costs while minimising environmental effect, says consulting engineers Zutari technical director Daniel Chelopo.
Renewable-energy consultants assist clients in exploring, comprehending and managing the process of integrating renewable energy into existing grid network, he says.
As a consultant, Zutari would investigate the energy sources used at the mining client’s facilities and determine whether alternative energy, such as wind or solar power, would be a better alternative.
However, considering that pre-existing power grids were constructed for traditional power sources with steady power outputs, the proposed wind or solar power may pose problems during deployment, owing to larger variations in the electric output and various types of sensitive equipment, emphasises Chelopo.
This necessitates the consideration of a hybrid system. Most hybrid systems exhibit significant variability, owing to the percentage of renewable energy running inside the system. They also lack controls and strategies because most lines and equipment were initially built for a reasonably steady electric flow from traditional nonrenewable sources, he explains.
To determine the type of hybrid system, the consultant would first review the engineering for the mine’s offtakes.
“This entails ensuring that the mine’s energy specifications complement the connection of the existing operations, and the initial planning and requirements,” explains Chelopo.
The next step is facilitating an agreement with the independent power producer, including the owners’ requirements and specifications, and a review of the contractor’s detailed designs.
While the integration of renewable energy can be achieved, Chelopo says integrating renewable power, such as solar photovoltaic (PV) and wind power, into a mining operation after construction, to achieve decarbonisation, poses a number of problems.
“Unlike traditional fossil fuel power generation, green power supply is unpredictable and dependent on a variety of circumstances.”
Therefore, these variable renewables, which produce energy intermittently instead of on demand, differ from traditional generating methods in several ways.
Firstly, a variable renewable-power generator’s output varies, given the fluctuation and unpredictability of the primary energy sources, which impacts on stability when incorporated into traditional power supply, explains Chelopo.
Variable renewable-energy systems also tend to comprise modular packages and are available in smaller sizes, making their implementation disruptive to the traditional or existing energy arrangement.
Moreover, variable renewables tend to be geographically limited, which generally implies that the conventional power source may have required significant expenditure to establish, resulting in a sunk cost realised during renewables integration or system replacement.
Chelopo adds that variable renewable-power generators, unlike traditional generators, are typically nonsynchronous and have low, short-run costs.
“These features pose difficulties to current power systems, with challenges defined in this context as factors that have a negative effect on the performance characteristics of an interconnected power system.”
Further, illustrations of the problems mentioned above, include insufficient transmission grid capacity and inadequate generation appropriateness, of which the latter refers to a current generating portfolio’s ability to always meet electrical demand.
Despite the technical variables; however, renewable energy in mining will minimise long-term dependency on fossil fuels, which are subject to global price fluctuations and inherently contribute to severe environmental consequences, says Chelopo.
As a result of this shift to renewable energy, a mine’s carbon footprint will be reduced and, when it meets the environmental and social criteria used to assess a project’s long-term viability and green credentials, it will appeal to future investors.
Therefore, creating a more environment-friendly power source has the benefit of price stability, says Chelopo.
Further, the cost of battery manufacturing is expected to halve over the next decade, allowing for large-scale energy storage to power mine operations, even in the absence of baseload supply.
Zutari has started implementing projects that include the planning and upfront design phases of renewable power plants in the form of solar PV installations into various mining companies and their operations across South Africa.
This looks at renewable power plants as embedded generation within the specific mining operations that will be connected on the mine’s side of the utility supply connection, says Chelopo.
The scope involves the planning and optimisation of the solar PV plant’s power output and the way the electrical connections are made into the current substations for each mining operations to be able to supply the power into the mine, he adds.
For the PV plant itself, the site selection, solar plant concept and feasibility designs are done. It also includes assessing the mine’s energy system, grid impact and compliance studies, as well as environmental assessments, highlights Chelopo.
He explains that the latest design modelling is being used and implemented in the mines and is based on the most recently available PV panels, trackers and inverter technologies.
Chelopo concludes that while most of the projects were initiated in 2020 or early in 2021, the first of the solar plants are planned to go into detailed design by either mid-2022 or towards the end of 2022.