Gold production processes use high levels of energy to take finished gold to market. Gold also has a higher greenhouse emission intensity per ton of product compared to other bulk metals.
But the relatively small volumes of gold produced each year mean total emissions from newly-mined gold are significantly lower than from other major products sourced primarily from mining, such as steel, aluminium and coal.
Gold is also valuable and, when analysed on a ‘per US$ value’ basis, research by the World Gold Council indicates gold has amongst the lowest emissions intensity of all metals and mined products.
In other words, the volume of greenhouse gas (GHG) emissions associated with a dollar spent on gold is lower than for a dollar spent on most other mined products.
Its research also suggests gold may have positive implications for long-term investors in helping them manage the carbon footprint of their portfolios over time.
In addition, gold itself may also play an important role in technologies that help facilitate the transition to a low carbon economy.
This work is an important initial step to build understanding of the gold industry’s greenhouse GHG footprint, the efforts already underway to reduce emissions and gold’s role in improving energy efficiency and developing low carbon technologies.
Leading responsible gold miners are actively making operational changes to reduce GHG emissions and this report features a number of examples of the progress made by the council’s members as they transition to a low carbon economy:
Borden: the ‘goldmine of the future’
Goldcorp’s Borden mine is set to become the world’s first all-electric underground gold mine.
The mine will replace current diesel-fuelled mobile equipment with Battery Electric Vehicles (BEVs).
The investment in electric equipment at Borden will improve safety performance and annually reduce GHG emissions by 70% (6,600 tons of CO2e).
Electric engines are three times more efficient than their diesel equivalents and reduce megawatt hours (MWh) by 33,000 per year due to the huge decrease in ventilation requirements.
Over a 10-year period, this represents a reduction of close to 70,000 tons of CO2e and 330,000 MWh in electricity.
With the decrease in emissions comes a reduction in underground ventilation needs, which will see Borden require 50% less ventilation than a baseline diesel underground mine.
The Borden underground mine will operate year-round on a continuous (24-hour) basis, at a rate of up to approximately 4,000 tons of ore per day when averaged over the year.
Solar power transforms the Esskane mine in Burkina Faso
IAMGOLD’s subsidiary, IAMGOLD Essakane SA, has partnered with Total Eren, AREN ENERGY and Essakane Solar SAS to source electricity from a 15 MWp (megawatt peak output) solar power plant to the company’s Essakane mine in Burkina Faso.
The agreement is for an initial period of up to 15 years and will help the company reduce its environmental footprint and electricity costs.
The project will allow integration of a solar plant into the mine’s existing 57MW HFO (heavy fuel oil) power plant, making it, at the time of construction, the world’s biggest hybrid HFO-solar power plant.
Essakane Solar will act as owner of the solar plant during the length of the contract, while IAMGOLD Essakane SA will act as a single buyer by purchasing all the energy produced. The inauguration of the first third of the solar plant took place on 16 March 2018.
The solar plant covers an area of 22 ha on the mine’s site.
Approximatively 130,000 photovoltaic modules are installed on the plant.
On a yearly basis, the fuel oil consumption will be reduced by approximately 6 million litres, representing a reduction of about 18,500 tons of CO2 emissions.
The capital cost of the project is US$25 million.
In addition to reducing the environmental impact and cost of electricity at the mine, the solar plant brings the key benefit of local employment.
About 100 local workers have been employed during the construction phase of the project and 40 more will be employed during the whole operation phase of the plant.
One per cent of revenues generated by Essakane Solar SAS will be invested in community projects around the mine.
These projects will be identified and implemented in partnership with local authorities.
Using science based targets, carbon pricing, and fuel switching to lower emissions
Newmont, in collaboration with the International Council on Mining & Metals (ICMM), is working to set meaningful science-based emission reduction targets for the industry and determine what must be done to achieve such targets.
Newmont is evaluating targets such as increasing renewable energy supply through self-generation or power purchase agreements as well as transitioning to electric and/or electric-hybrid vehicles.
A key success thus far has been expanding the use of fuel efficiency technologies, such as the Blutip solution Newmont implemented at its Boddington operation, which has reduced diesel fuel consumption by 5.2% and GHG emissions by 10,000 tons on an annual basis.
In addition, fuel switching to lower emissions sources has been a vital component to Newmont’s 2020 emission reduction goal, and a key example for this is Newmont’s Tanami power project.
In early 2017, extreme weather in Australia’s Tanami desert led to widespread, sustained flooding.
For two months, diesel, which is the primary fuel source for the mine, could not be trucked into the site.
As a result, production – at an average of 8,000 ounces of gold per week – was shut down during the month of February.
To improve energy security and mitigate climate change risk, Newmont conducted a review of options including an analysis of the cost of carbon, giving the company greater visibility into each option’s embedded carbon risk and exposure to future carbon pricing schemes.
The price of carbon was analysed at US$25 and at US$50 per ton of carbon dioxide equivalent (CO2e).
These price points were based on current carbon pricing used by mining and energy companies.
The review resulted in Newmont approving the Tanami Power project, including the construction of a 280-mile long (450 km) natural gas pipeline, which is set to deliver a consolidated energy solution for the mine by providing reliable, gas-fuelled power generation.
Switching from diesel fuel to natural gas is expected to reduce annual energy costs and carbon emissions by approximately 20% beginning in 2019.
In addition, in 2017, Newmont established a target to reduce its GHG emissions intensity by 16.5% by the end of 2020, measured from a base year of 2013.
To date, Newmont has achieved a 15.6% reduction, with the company on track to achieve an additional 1% reduction by the end of 2020.
Optimised underground ventilation system reduces energy consumption and emissions
Barrick’s goal is to reduce its greenhouse gas emissions by 30% by 2030 from a 2016 baseline.
Currently, 36% of the Barrick’s electricity comes from renewable sources. It is deploying a number of initiatives to reduce overall GHG levels, including the evaluation of moving to a lower emission fuel at its power plant in the Dominican Republic and designing future mines to include electric and automatic equipment.
The business impact of the reduction in energy demand, consumption and GHG emissions is evident at Barrick’s Hemlo mine in Canada.
Hemlo developed a site-wide ventilation management programme to facilitate continuous improvement and spur innovation in technology, people and systems.
As a result, Hemlo was able to drive down energy consumption and GHG emissions by optimising its underground ventilation system.
It implemented ventilation on demand (VOD) in targeted areas of the mine and fans without VOD were managed exclusively by trained personnel.
Hemlo also reduced heating costs by taking advantage of the mine’s naturally-occurring geothermal properties.
The mine was able to draw fresh air via the stopes in old mining areas to create an air supply that did not need heating in winter, whereas in summer, ice stopes cooled the air.
Energy consumption as measured by ventilation per tonne of ore fell from 96.7 kilowatt hours per tonne (kWh/t) in 2013 to 86.1kWh/t in 2015; a reduction of 24% in GHG emissions and a decrease of 10% in energy consumption over two years.
In recognition of this innovative approach to conserving energy, in 2016 Canada’s Department of Natural Resources awarded Hemlo the ‘Process and Technology Improvement Award.’
Since 2016, mining operations at Hemlo have expanded but the mine has been able to maintain similar levels of energy intensity, demonstrating the enduring impact of these innovative solutions.
Reducing GHG by hydro power and optimisation of haulage conditions
Kinross is constantly reviewing its energy supply matrix in order to identify opportunities to reduce both costs and emissions.
It has recently acquired two hydroelectric power plants (155 MW installed capacity) in Brazil that will ensure sustainability of a renewable energy supply for its Paracatu operation.
Fuel for mining operations represents the largest category of direct emissions. There is an intense focus on optimisation of haulage conditions and driver training as these produce fuel savings, cost reductions and reduced emissions.
Route optimisation work at the Bald Mountain mine in Nevada has saved more than 15,000 hours of haulage time since January 2017, while at the Fort Knox mine in Alaska time savings of over 10% have been made on every haul truck cycle to the heap leach pads.
The operators of haul trucks are trained with simulators to develop optimum driving skills that economise on fuel consumption.
Kinross is currently implementing a number of capital projects too, incorporating energy efficiency into the design of its operations from the onset.
These energy management projects are set to contribute to further GHG savings.
Automatic compressed air control reduces energy consumption
In 2016, AngloGold Ashanti’s Vaal River mine won the ‘Project of the Year’ award from the South African Association for Energy Efficiency for its Vaal River Compressor Real-time Dynamic Control System (REMS-DCS).
The Vaal River mining complex consumes 250 megawatt hours (MWh) per day for the supply of compressed air.
The intricate network consists of 37 MW of installed compressors along a 27 km surface piping network, with multiple users situated on the surface and underground.
To reduce energy consumption, and thereby reduce its carbon footprint by 4,400 tons of CO2 per annum, AngloGold Ashanti implemented a real-time dynamic control system (REMS-DCS) to optimise and automate its compressor controls.
The project achieved an energy reduction of 1.65 MW during the evening peak period and realised an annual saving of approximately US$140,000, although the total savings from multiple parallel projects on compressed air efficiency amount to almost twice this sum.
Full automatic compressed air control on this magnitude has never previously been achieved in the mining environment.