Mining for the Energy Transition
Chuquicamata mine in Chile is the largest open pit copper mine in terms of excavated volume in the world. Image source
Mining is not exactly a low-impact activity. It is not sustainable in the technical sense of the word, and never can be. Once minerals are dug up or extracted, it’s never going back. In the past, it was simple: mining was bad for the environment. Environmentalists opposed mining, and supporters of mining were not environmentalists. But ever since we became aware of climate change a few decades ago, environmentalism didn’t only mean protecting local environments, it also meant protecting the global climate. Now the solution to climate change is well understood, it’s an energy transition. We get rid of placement of fossil fuel-based technologies like coal fired power plants and petrol cars with renewable energy sources such as wind turbines, solar panels, electric vehicles and batteries.
This transition, however, underscores a critical realization: the indispensable role of mining in achieving sustainable energy goals. The materials necessary for the construction of renewable energy infrastructure—iron, copper, lithium, nickel—are products of mining.
This creates a paradox for a stereotypical environmentalist: mining is bad for the environment but to save the environment we need to mine.
The problem in context
As the world shifts towards renewable energy sources in the energy transition, the demand for minerals and metals is expected to rise, not decline. It has been said that the energy transition is going to need more mining overall than the fossil fuel status quo, but that’s not accurate.
It is true that on average, manufacturing clean energy products uses more minerals than manufacturing fossil equivalents. An electric car needs 6x the amount of minerals as a petrol car for example and an onshore wind farm needs 4x more mineral resources than a coal-fired plant. But manufacturing isn’t the whole story, we need to consider the entire lifecycle. The primary motivation for transitioning away from petrol cars and coal-fired plants is their ongoing fuel consumption and resultant greenhouse gas emissions. When you include the extraction of fuels, fossil fuel technologies consume a greater volume of mined resources compared to renewable alternatives. Moreover, the lifecycle emissions perspective highlights a key advantage of renewables: while fossil fuels release greenhouse gases each time they are burned, the minerals used in technologies like batteries offer the potential for repeated recharge and ultimately, recycling, thus presenting a more sustainable solution in the long term.
Both EV and wind farm demand less minerals compared to conventional car and coal-fired power plant respectively. Source
Let’s look at just one example, a petrol versus an electric vehicle. Throughout its life, a typical car with an internal combustion engine burns roughly 17,000 liters of petrol. In contrast, the metals in battery cells weigh approximately 160 kg, one hundred times less. Furthermore, considering the recycling of battery materials and the fact that most of the metal content can be reclaimed, only about 5-30 kg of metals will be lost for the average battery, at most 1.8 kg of lithium, 0.4 kg of cobalt, and 1.4 kg of nickel, equivalent to the size of a football. In comparison, the weight of petrol or diesel that gets burned during a vehicle's average lifespan is hundreds of times more than that. Even with no recycling of batteries, we’re looking at about a 99% reduction in the amount of mining needed for an EV compared to a petrol car, and when you include recycling, it’s more like a 99.9% reduction.
There are far less mined materials consumed in petrol cars than EVs when fuel is included. Data from T&E
With this in mind, isn’t it unfair to target mining associated with energy transition technologies while ignoring mining for fossil fuels? As we phase out fossil fuels, the emissions from their mining will naturally decrease, so the problem will get smaller. It is crucial to focus on making mining for essential minerals like iron, copper, and lithium emission-free, as they are vital for our shift to a zero-emission future.
Emissions in the Mining Industry
Let’s look at the common processes in mineral mining and where exactly emissions come from.
Extraction
The first step in mining is extraction: blasting or digging and then hauling material away to be processed. Emissions from extraction come from fossil fuels in mining equipment, vehicles, and facilities, or in machinery like drills, excavators and transport trucks. in addition to onsite electricity generation. All these energy demands have traditionally been met by diesel but can be electrified or use hydrogen or biofuels to reduce emissions.
Beyond the direct emissions, we also encounter indirect ones from supply chains, such as the production and transport of steel for mining equipment, and from offsite electricity generation used in mining operations. As the overall economy shifts towards decarbonization, these indirect emissions are set to decrease.
Land clearing for mining sites introduces another source of emissions. While not the largest contributor to global warming potential, open cut mining in forested areas disrupts ecosystems and leads to biodiversity loss, particularly in countries like Brazil, Indonesia, Peru, and the Democratic Republic of Congo. These nations face deforestation challenges associated with mining for bauxite, nickel, copper, and cobalt. Finding alternative mineral sources not located beneath forests could mitigate this impact. Rehabilitating sites afterwards needs to be funded properly and done with care.
Tropical rainforest cleared due coal mining in East Kalimantan, Indonesia. Image Mokhamad Edliadi/CIFOR
Processing
Moving on to ore processing, we refine the raw materials into usable metals. This is an exercise in concentration. Most of the mined material is typically stuff that is not valuable to the miners, and the concentration of the good stuff can range from 30-65% in the case of iron ore, down to 0.6% or even less for copper. In either case, or anywhere in between, to get to a purer form of the metal it needs to be processed. Large rocks get crushed into small particles, those particles get roasted or leached or smelted or a combination of all of those or other chemical reactions.
Crushing and grinding stand out as particularly energy-intensive processes. In fact, a staggering 3% of the entire world's electricity is devoted to this task. Smelting is another major consumer of energy, used to extract metals by heating ore beyond the melting points of the desired metals. My previous discussions on zero-emission industrial heat technologies delve into ways to mitigate these emissions, and it's worth noting that reduction reactions can also generate significant emissions, as explored in my coverage of iron ore reduction.
There are other chemical processes used to extract or purify minerals. Calcination, leaching, floatation, pyrometallurgy are some examples of energy intensive or emit greenhouse gases directly.
Waste management
After all that processing, we have a purer form of the metal, however we also have a whole lot of waste. Waste management is needed to preserve the local environment, and many waste management practices carry a carbon footprint. For instance, the use of lime to neutralize acidic mine waste is a common practice; while it plays a pivotal role in mitigating local environmental damage, the production of lime itself releases a lot of CO2.
Additionally, the natural decomposition of carbonate minerals like siderite FeCO3 and calcite CaCO3, found within waste rock and tailings, contributes to emissions during processes such as weathering, neutralization, acid leaching, and metallurgical processing. This can be a big one, for example, degradation of carbonate minerals has been estimated to contribute almost 8% to GHG emissions at BHP Billiton’s Olympic Dam copper–uranium–gold–silver mine in South Australia.
Transport
Lastly, the transportation of mined materials to processing sites or export ports introduces additional emissions, depending on the transportation method. Like the broader transport sector, mining can look towards electrification and alternative fuels like biofuels or hydrogen derivatives for emission reductions.
Zero Emissions Mining Future
Navigating the path to a zero emissions mining future isn't as straightforward as ranking emission sources and applying a one-size-fits-all solution. The complexity arises because emission sources vary widely across different minerals. For instance, in iron ore mining, the bulk of emissions stem from loading and hauling, whereas for copper, the primary culprit is the energy-intensive process of crushing and grinding. Furthermore, the mining methods for a single mineral can differ dramatically depending on the location, such as lithium mining from Australian spodumene rocks compared to extraction from South American brines, leading to vastly different emission profiles.
Iron ore mining, main emissions sources are loading and hauling. Source Norgate, Hague 2010
Copper mining, main emissions sources is crushing and grinding. Source Norgate, Hague 2010
Moreover, even within a single mine, processes and associated emissions can evolve over time due to factors like mine depth and ore grade changes. This dynamic nature of mining operations means there's no one-size-fits-all solution to achieve zero emissions across the board.
Given these complexities, a comprehensive overview of zero-emission solutions for every conceivable mining scenario is beyond what I can achieve in this article. Instead, let's zoom in on specific, tangible examples from the mining of iron and copper—two minerals with significant total emissions due to their massive global production volumes, and both metals that we need more of for energy transition technologies. Although iron and copper’s emissions per kilogram might not compare with those of precious metals like gold, platinum, or palladium, the global scale of iron and copper production makes their overall impact substantial. By focusing on these examples, we can shed light on effective strategies being implemented to reduce and ultimately eliminate emissions in the mining sector, crucial for powering our energy transition.
Emissions intensity and total emissions of mined metals. Source Azadi et al 2020
Current Progress
Iron mining
Fortescue Metals Group, the world's fourth-largest iron ore producer, is ambitiously aiming for "real zero" emissions by 2030. Their strategy encompasses a broad spectrum of projects, primarily focusing on renewable energy and the electrification or hydrogenation of heavy machinery, haul trucks, and shipping vessels. A notable project was their 2022 Energy Connect initiative, which integrated solar panels, batteries, and high-voltage transmission lines to replace the majority of diesel generators across various sites.
The Infinity Train project exemplifies their ambition. This electric train recharges using gravitational potential energy from descending loaded from the mine to the port, eliminating the need for external charging. Looking beyond their 2030 scope 1 and 2 emissions targets, Fortescue is exploring green ammonia or methanol for shipping and a low-temperature electrolysis method to produce green steel from iron ore without coal. A pilot of this process was launched in 2023, potentially revolutionizing steel production, which currently accounts for 8% of global emissions.
In the realm of loading and hauling, Fortescue leads with its commitment to electric machinery, exemplified by their plan to deploy a massive 3MW charger for trials in 2024. The company is also leveraging solar and wind energy, complemented by battery storage, to drastically reduce diesel dependency and lower operational costs, moving closer to fully renewable-powered mining operations. Additionally, Fortescue's advancements include the deployment of the world's first green hydrogen-powered haul truck at their Christmas Creek mine, showcasing a tangible step towards their zero-emission goals. And for emissions sources lacking current commercial solutions, Fortescue has innovated, such as developing partnerships for battery-powered or hydrogen fuel cell haul trucks and Heavy Mobile Equipment that can connect directly to the grid.
Fortescue rolls out 3MW fast charger as it trials electric haul trucks. Source Fortescue Future Industries
Copper mining
In copper mining, crushing and grinding are the most significant energy demands. Innovative strategies are being employed to reduce emissions. A recent study highlighted that cutting-edge comminution technologies can decrease energy consumption by 40%, with enhanced blasting techniques further reducing the need for energy-intensive crushing. Transitioning to renewable energy sources can then address the remaining emissions from these processes.
Antofagasta, a prominent player in the copper industry, has made remarkable strides by achieving a 90% reduction in scope 2 GHG emissions since 2021, by transitioning to 100% renewable electricity for its operations and electric trucks and ancillary mining equipment. The company capitalized on Chile's abundant and cost-effective renewable energy resources to power its operations.
At the Centinela mine, Antofagasta has implemented a solar thermal plant, which harnesses solar energy to produce heat and electricity. Solar thermal technology uses mirrors or lenses to concentrate sunlight onto a receiver, where it is converted into thermal energy. This energy can then be used directly for industrial processes or to generate electricity, reducing the reliance on fossil fuels.
At the Los Pelambres and Zaldívar mines, Antofagasta has introduced innovative conveyor belt systems that contribute to self-generation of electricity. These systems are designed to capture the energy generated during the downhill transport of ore, similar in concept to Fortescue’s Infinity train idea. As the loaded conveyor belts descend, they drive generators that produce electricity, which can then be used to power various operations within the mines. This not only reduces the need for external power sources but also capitalizes on the potential energy inherent in the mining process.
Solar thermal plant in Antofagasta’s Centinela mine. Source
In wrapping up, we're faced with a stark reality: the mining industry, with its checkered environmental past, stands at a crossroads in the face of climate change. The paradox is as clear as it is challenging—the very materials that are pivotal for the renewable technologies driving the energy transition are borne of an industry that has been, to put it mildly, less than stellar in its environmental stewardship.
But here's the rub: unlike fossil fuels, which we can and must phase out, the materials mined from the earth are irreplaceable in the machinery of our zero-emissions future. We can't simply wish away the need for mining.
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