Large-Scale Battery Storage In Mining — Where Are We Now?

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Power uptime is critical for big mines and other energy intensive industries. As some of these energy intensive energy industries can be located in places that are far from the grid or in places with weak and intermittent grids, they generally have a fleet of large thermal (heavy fuel oil or diesel) generators to ensure power uptime, and therefore often have a large diesel/oil bill.

Technological advancements in the renewable energy sector in areas such as intelligent controllers to ensure seamless integration of solar PV, battery storage, grid and diesel generators, as well as a proven track record of performance from some active sites around the world, are giving mining companies and other heavy industries some confidence to adopt solar PV, and more recently large scale battery storage, in their operations where possible. The other main driver of this adoption is the significant operational cost reduction derived from adding these technologies to their operations. The drastic drop in  the prices of solar panels and batteries over the past ten years that has made it possible for these technologies to be competitive with traditional sources.

JUWI South Africa and JUWI Australia, wholly owned subsidiaries of the global JUWI Group, are some of the leaders in the development of large hybrid power projects. For JUWI, its hybrid projects include both on-grid and off-grid projects incorporating various combinations of PV, wind, and battery (BESS) technologies. Grid-connected projects include two configurations:  ‘behind-the-meter’ where the renewable plant is co-located with the mine, and projects where electricity is generated remotely and then “wheeled” through the national grid. One hybrid project example is a solar PV plant on a mine in Mpumalanga, South Africa, which is connected to the national utility (Eskom) grid and where the PV plant is on the mine premises. Another is an off-grid mine in Egypt that is powered by solar PV, battery storage, and a thermal plant that was previously the only source of energy for the mine.

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A key issue in the roll-out of large scale projects is the integration in real time of different types of technologies and the power they generate. The main goal, especially for mines, is to avoid any downtime. Often this also involves cloud forecasting in order better to anticipate weather and allow the mine to get the best blend of energy security and cost savings. JUWI has been working in this area for a number of years. While the company remains technology agnostic, they have done  a lot of work with Siemens in particular (one of the suppliers of control system hardware and software). JUWI and Siemens now offer a Hybrid IQ controller product that intelligently integrates and manages renewable energy and battery storage supply with mines’ thermal back-end generation facilities.

Some features of a typical system include, but are not limited to:

• Power production forecasting using cloud cameras, wind measurements and weather data
• Optimized dispatch and battery charging and discharging
• Integrates conventional, renewable and battery energy supply
• Fully scalable accommodating generation expansion as mines grow
• Robust & suitable for extreme environments

So how is the hybrid power integration landscape looking like currently? Integrating a significant portion of solar helps cut the diesel or thermal bill, thereby reducing costs. JUWI South Africa’s Managing Director, Richard Doyle, says that it is now possible for mines to get a significant percentage (50% – 80%) of their electricity from renewable energy plants. Going fully off-grid with PV and battery energy storage is still not a commercial solution for mines. However, using smaller batteries (typically C1 or 1 hour duration batteries) very effectively manages the intermittency of the PV and gives the thermal generators time to start up and take over from the solar PV when there are clouds. Viable mining project sizes generally start at about 10 MW.

Doyle says that until very recently, most energy intensive users in South Africa, including data centers, smelters, and other large industrial users have depended on the grid so that batteries have not been a focus (due to costs). However, the degradation of the Energy Availability Factor of the country’s aging coal plants and the resulting load-shedding in the country has changed things. Generators are already deployed widely albeit reluctantly, which opens up the opportunity for energy storage to mitigate costs and carbon.

On the corporate sustainability front, increasing fuel prices and carbon emissions are negative factors and as companies start setting ESG targets, programs to reduce emissions and operations costs are now taking center stage. Batteries are increasingly being considered for energy security now and the costs are compared to the cost of unserved energy rather than the cost of diesel or the grid. Scheduled outages or load-shedding takes place for 2–4 hours and in many cases more than once a day so that longer battery deployment is also being considered. The national government’s Risk Mitigation Independent Power Producers Procurement Programme (RMIPPPP) asked for 8 hours of BESS and resulted in a lot of modelling and pricing for PV and wind + 8 hours of BESS and created awareness around the economics of longer battery life.

JUWI adds that there are two significant other developments. Eskom has launched and awarded tenders for the first of two large battery projects. This is to provide spinning reserve to the grid, and the economics are not based on the replacement costs (the wholesale price of electricity in South Africa) but on the cost of auxiliary services and unserved energy. Secondly, the small C&I and household solar PV and battery market is exploding and driven by the need for constant energy as a “license” to operate for businesses.  For households it is largely focused on higher LSM band buyers that are now able to afford or extend their bonds for the R100k – R200k required to go “substantially” off grid.

Globally, the JUWI Group has installed over 6,500 MW of renewables. The company has developed 20 hybrid (renewables with battery) projects globally with a total capacity of 170 MW (130 MW solar + 35 MW wind). JUWI also developed and constructed the DeGrussa Mine in Western Australia, which has a 10 MW solar farm plus 6 MW battery storage. This was followed by Agnew Gold (Australia) in 2019 and another six hybrid projects in Australia and Africa for tier 1 and mid-tier miners: Esperance, Pan African Resources,  Centamin, Jacinth Ambrosia, Jabiru, Weipa, and Gruyere.

An example of a mining site with large battery storage developed by JUWI on the African continent is the Sukari solar plant in Egypt for Centamin. The plant comprises a 36 MW solar farm and 7.5 MWh battery energy storage system commissioned in late 2022. This plant is saving the client up to 70,000 liters of diesel per day or 22 million liters per year. Based on current diesel prices, this means the plant has the potential to provide annual cost savings of $20 million, alongside an expected reduction in Scope 1 greenhouse gas (GHG) emissions of 60,000 t/y CO2 equivalent and a subsequent reduction in volume of diesel trucked to site. With Sukari, JUWI will provide a new benchmark of power systems for mines in Africa and internationally.

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Part of the hybrid plant at  Sukari, Egypt. Images courtesy of JUWI