Miners turn to batteries to clean up energy use

Mining groups looking to cut their emissions are counting on energy storage systems to increase their renewable power consumption.

The mining sector is a significant emitter of greenhouse gases and the industry knows that it needs to reduce its carbon footprint, both to tackle climate change and meet the expectations of investors, regulators and customers who want to decrease the environmental impact of their supply chains. 

One way the industry can achieve this is to power more mining operations using wind or solar energy. Because the cost of these technologies has fallen rapidly in recent years, this is not simply good for mining companies’ environmental footprint – it can save money, too. However, such renewable energy sources are inherently intermittent, so on their own cannot provide consistent and reliable power. But when you add energy storage, their contribution increases significantly.

Power consumption is one of the biggest contributors to the sector’s emissions, says mining consultant Andy Birtles, a fellow of the Institute of Materials, Minerals and Mining. “There is some incredible energy usage in mines, often in excess of 10MW. Power can account for up to 40 percent of a mine’s costs, so anything that can bring down those costs will be a good thing.”

Many mines are so remote that they are hundreds of miles from power grids. As a result, they have tended to use diesel generators to provide the electricity they need to operate. However, as the cost of renewable power has fallen in recent years, the remoteness of many sites and the expense of buying and transporting diesel to run generators has made switching to renewable sources of electricity “increasingly feasible, even in off-grid environments,” according to the consultancy McKinsey.

The benefit of energy storage

Although many mines are located in sites with good wind or solar resources, they have been limited in how much renewable energy they can use due to the intermittency of the wind and sun. Mining groups are increasingly addressing this by adding battery energy storage systems (BESS) to renewable energy facilities.

One of the first examples of how battery storage can help make mine energy supplies more resilient and sustainable is Gold Fields’ Agnew Gold Mine, located in a remote part of Western Australia, 1,000km north-east of Perth. Distributed energy producer EDL has developed Australia’s largest hybrid renewable-energy microgrid at the mine, comprising a 4MW solar farm, 18MW of wind capacity, a 21MW gas/diesel engine power plant, and a 13MW/4MWh Saft lithium-ion battery energy storage system.

The BESS allows the microgrid to maximize the amount of renewable energy it uses by compensating sudden variations in the power output of solar panels and wind turbines. The system will provide ultra-fast reacting spinning reserves to help maintain grid stability, which reduces the need to have diesel generator sets running idle for this purpose.

The hybrid system means that the microgrid will operate reliably with up to 85 percent of the power coming from wind and solar generators. On average, 50 to 60 percent of the mine’s electricity needs can be met by renewable energy. The project is set to abate and avoid 46,400 tonnes of carbon dioxide equivalent (CO2–e) a year, comparable to taking 12,700 cars off the road. Gold Fields recently announced it wants to have 99 percent of the mine’s power coming from renewable sources in future.

Building momentum

Some 35 percent of Australia’s 400 mines are not connected to a power grid, the Australian Renewable Energy Agency (ARENA) says, so there is huge potential to cut costs and emissions by installing renewable power and battery storage. Now that companies such as Gold Fields are using BESS technology, momentum in the industry could grow. Birtles says: “Miners are a conservative lot. They don’t like to try anything unless someone else has already done it. But once one company does it, they all jump on the bandwagon.”

This momentum will be helped by the fact that the cost of renewable energy is so much lower now, and the cost of batteries is following suit thanks to the rapid growth of the electric vehicle market. So says Sebastien Hita Perona, energy storage solutions general manager at Saft. “We are at grid parity for renewables,” he explains. “Energy storage solves renewables’ intermittency and allows them to be integrated into baseload resource planning.”

Clean-energy analysts BloombergNEF point out that lithium-ion battery pack prices, which were above $1,100/kWh in 2010, have fallen 87 percent in real terms to $156/kWh in 2019. By 2023, it estimates that average prices will be close to $100/kWh.

Prices are falling not just because of technological improvements and economies of scale as production is ramped up, but also advances in the way plants are managed, says Hita Perona. “We can forecast much better how much renewable power will be generated, so we know when we can store power in the batteries.”

Gold Fields is one of the first companies to promote hybrid schemes for mines, he points out, adding: “We’re at the very start of a huge change in power generation for mining.”

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