Miners pursue green goals, above and below ground, with the help of batteries

Using renewable energy to replace diesel generators and working with electric vehicles in mines is helping commodities producers to meet emissions targets.

Like every other sector of the economy, the mining industry is under pressure to cut its greenhouse gas emissions. As a result, mines are starting to use more renewable power to provide much of their electricity. But this can be challenging, given that wind and solar resources are intermittent and therefore not always available when they are needed.

Building into renewables

One of the ways the industry is overcoming this is by using battery energy storage systems (ESS) that capture surplus energy when it is not needed and store it to use it when the wind is not blowing or the sun is not shining. By doing this, mines can greatly extend the amount of renewable power they have available and cut their consumption of fossil fuel-powered equipment such as diesel generators.
With many mines situated in remote areas, this has the double benefit of making the site less polluting and reducing the need to transport diesel fuel, sometimes for thousands of kilometers, to provide fuel for electricity and back-up power. At Gold Fields’ Agnew Gold Mine, 1,000km north east of Perth in Western Australia, a hybrid energy system has been installed, comprising a 4MW solar farm, 18MW of wind capacity, a 21MW gas/diesel engine power plant, and a 13MW/4MWh Saft lithium-ion (Li-ion) battery energy storage system.
In the right weather conditions, up to 85 percent of the mine’s power can come from wind and solar generators, and on average 50-60 percent is clean power, avoiding 46,400 tonnes of carbon dioxide equivalent (CO2–e) a year, comparable to taking 12,700 cars off the road.

Going electric underground

However, it is not just above ground that mines are becoming more electric. Electric equipment has always been used, but has been limited by the fact that the machines needed to be connected to an electricity supply by power cables, reducing their flexibility. But recent developments in Li-ion battery technology means mines can deploy zero-emission vehicles that can travel anywhere within the mine.
Saft’s latest Li-ion battery technology is ideally suited for underground mining vehicles because it combines high performance, high energy density, reliability, safety and long life, even at extreme temperatures ranging from -25°C to +55°C. 
Our improvements in battery performance are timely as mines are being dug deeper underground in the hunt for resources, reaching depths of up to 4km. This creates health and safety issues when using conventional diesel-powered equipment, as well as increasing costs and reducing efficiency. Diesel engines emit CO2 and NOx and fine particulates, which need to be evacuated and filtered by ventilation infrastructure. 
In addition, as mines extend deeper underground, the ambient temperature rises. If miners use diesel machines, they not only create air pollution within the mine, but also increase the air temperatures still further.

Lower running costs

It is estimated that around 80 percent of the energy costs for underground mining operations are associated with load, haul and dump machines and vehicles that move people and equipment through the mine. If you remove diesel emissions, you also take away a major burden for ventilation systems, which can be simpler and smaller. 
As a result, electrification can now help commodities producers save on the cost of fuel and the expense of building and running ventilation and cooling systems in mines, as well as improving energy efficiency and safety. These savings can be considerable – a typical deep mine using diesel-powered vehicles might need a 20-30MW cooling plant. Electrification can reduce that load to a quarter of the previous value.
Studies show that diesel machinery is three times as costly per ton of material handled as electric machinery. And if the electricity comes from locally generated renewable sources, the savings are even bigger. 
Battery electric vehicles (BEVs) also have fewer moving and wearing parts means less maintenance – repair costs can be cut by up to 40 per cent. It also means less noise and vibration, which creates a more productive and safer working environment.

Demand from stakeholders

All of the environmental problems associated with diesel, and the fact that BEVs now offer a feasible and cost-effective alternative, means that pressure is growing from investors and governments to phase out diesel machinery. Natural resources consultancy BDO recently predicted that new mines in Australia would not use diesel by as early as 2023, with existing underground mines starting to phase them out as well. Other mining regions of the world are likely to follow suit, and batteries are set to play a major role in decarbonizing the industry, both above and below ground.

Pierre-rene.houdart@saftbatteries.com