Energystoragelooks to be the logical next step for a growing number of mining companies using renewables to offset high power costs. Last year saw at least two major mining firms announcing storage projects amid a rush to install solar and wind generation.

Both projects are taking place in very different environments. Glencore plans to use a combination of storage technologies, including hydrogen and a flywheel, for wind power in Arctic conditions, while Rio Tinto Alcan will be using batteries for PV in the Australian outback.

The Glencore energy storage facility, at the company’s Raglan nickel-copper mine in the far north of Canada, was due for completion this month. It is made up of a flywheel, batteries and an electrolyzer, plus fuel cells for hydrogen storage, all linked to a single Enercon turbine.

“Once completed, the facility is expected to reduce Raglan’s diesel consumption by over 50 percent,” according to  Glencore.

“During periods of high wind, power surpluses will produce hydrogen [via electrolysis of water], which will be stored in compressed gas tanks. When the local power grid for the mine needs additional energy, the hydrogen will be used as fuel.”

If the system works, there are plans to develop two wind farms with four turbines each, and associated storage facilities, around the current 3-megawatt machine. As well as powering the mine, the hydrogen could be used as a vehicle fuel, according to reports.

A desire to reduce traditional fuel consumption is also the driving force behind the project being developed at the Weipa bauxite mine in far north Queensland for Rio Tinto Alcan by First Solar and Ingenero, an engineering group.

The first phase of the AUD $23.4 million (USD $18.1 million) project, which also serves Weipa’s township and port, was for a 1.7-megawatt thin-film PV plant to offset up to 20 percent of existing diesel-generated electricity.

A second stage of the project, due for completion in 2017, will see the solar farm being extended to 6.7 megawatts and battery storage being added to provide up to 100 percent of the daytime energy needed by the mining community.

Ivor Frischknecht, CEO of the Australian Renewable Energy Agency (ARENA), which has committed a total of AUD $11.3 million (USD $8.7 million) to the project, said in press comments that Weipa could be used as a blueprint for other mining operations.

“ARENA has made it a priority to work with major mining companies to find solutions and overcome roadblocks associated with integrating renewable energy into off-grid locations,” he said.

Dan Brdar, CEO of the battery converter maker Ideal Power, said there is an obvious business case for energy storage in mining. "Mining operations are often in remote and undeveloped locations, making grid access both difficult and cost-prohibitive,” he said.

“Many of these operations rely on diesel generators, which can also be expensive, not only for the cost of the fuel, but also for maintenance and upkeep.

“With battery costs declining, it allows them to assume much of the work being done by diesel gensets, which can reduce fuel costs by more than 70 percent,” Brdar said.

He suggested that “a microgrid solution that includes diesel and PV together with battery storage is the ideal solution to fulfill [mining operations'] power requirements.”

But other options may work better under certain circumstances. At Glencore’s Raglan site, 1,120 miles north of Montreal, freezing conditions mean batteries may only have limited use, so hydrogen is an obvious choice.

Elsewhere, mining companies may choose technologies that can make use of old excavations.

The Natural Resources Research Institute of the University of Minnesota Duluth, for example, believes the water-filled pits in Minnesota’s Iron Range could be used as pumped hydro reserves. And disused mine shafts have clear potential for compressed air energy storage (CAES). 

“It definitely is a cost-effective and attractive solution, since the excavation costs would be eliminated from the capital expenditure,” said Giw Zanganeh, head of energy storage technologies at Airlight Energy, a Swiss renewable technology developer working on CAES.

“Since CAES is already one of the most, if not the most, cost-effective technologies for electricity storage, this would definitely be an interesting option.

“However, if there is active mining going on in the vicinity, the safety measures need to be evaluated thoroughly in order to ensure that there is no risk for the active mining shafts and hence for the workers operating there.”

Safety is an issue very high on the mining industry’s priorities. But for a company such as Glencore, which lists energy as the second-largest budget item at Raglan, cheaper power is also pretty important. Energy storage increasingly seems like part of the way to obtain it.