By Umar Ali
Mining is one of the most energy-intensive industries on the planet, but it is also one of the most important, with commodities from base metals to rare earths in high demand. Many mining companies have however begun incorporating renewable power sources into their operations, offsetting some of the carbon costs of mining. Umar Ali profiles some of these green mining projects.
Renewable certificates at Rio Tinto’s Kennecott mine
On 1 May 2019, Anglo-Australian mining multinational Rio Tinto announced that it would reduce the annual carbon footprint associated with its Kennecott Utah copper mine by as much as 65%, by purchasing renewable energy certificates and permanently shutting its coal power plant.
The mine’s electricity needs will now be supplied with 1.5 million megawatt hours (MWh) of renewable energy certificates supplied by energy company Rocky Mountain Power, primarily sourced from its renewables portfolio in Utah and including wind power from Wyoming.
This latest decision follows other green initiatives at Kennecott, including the recycling of smelted scrap metal from its operations since 2005, through which the company processed more than 2.8 million pounds of copper in 2018.
“Rio Tinto is committed to playing a part in the transition to a low-carbon economy,” said Rio Tinto CEO Jean-Sebastien Jacques in a statement. “This move will significantly reduce emissions associated with our operations in Kennecott and allow us to offer customers copper, gold and silver with a reduced carbon footprint.
“The materials we produce, from infinitely recyclable aluminum and copper used in electrification to borates used in energy-efficient building materials and our higher grade iron ore product, all play a part in this transition to a low-carbon economy. Rio Tinto will continue to work with partners and customers to develop new sustainable solutions”.
Wind, solar, gas and batteries for Gold Field’s Angew mine
In June 2019, South African mining company Gold Fields announced its plans to predominantly operate its Agnew gold mine in Western Australia (WA) using renewable energy.
This move to renewable energy is in partnership with global energy group EDL and involves an AUD112m ($77.59m) investment in an energy microgrid combining wind, solar, gas and battery storage.
The project has also received support from the Australian Government with the, Australian Renewable Energy Agency (ARENA) contributing a recoupable AUD13.5m to the construction of the microgrid. Construction has already started for the development of the microgrid, which will be owned and operated by EDL.
“At Agnew we will be using instrumentation to detect approaching cloud cover for solar and, potentially in the future, detect changes in wind velocity,” Gold Fields Australia Executive Vice-President Stuart Mathews said. “Based on this data, the gas power station will have forward-looking systems in place to schedule gas generators in response to forecast changes in the renewable energy supply.”
The microgrid will be comprised of five wind turbines capable of delivering 18 megawatts (MW) of power, a 10,000-panel solar farm contributing 4MW and a 13MW/4MWh battery energy storage system. The grid will also be supported by a 16MW gas engine power station, and is expected to initially provide between 55% and 60% of the mine’s energy requirements.
100% renewable in Chile, Antofagasta Zaldívar mine
In June 2018, Chilean copper mining company Antofagasta signed an agreement with utility company Colbún to make the Zaldívar mine the first Chilean mine to operate with 100% renewable energy.
From 2020 the mine will be powered by a mix of hydro, solar and wind power producing 550 gigawatt hours per year, which is expected to remove emissions equivalent to 350,000 tons of greenhouse gases per year.