Mining is at the centre of a paradox in the era of climate change. Historically, mining and environmentalism stood on opposing sides; the extraction of resources was seen as an irreversible harm to the earth. However, the advent of climate change awareness has shifted this perspective. It is now understood that the solution to climate change is an energy transition: replacing gas and coal-fired power plants and petrol cars with renewable energy technologies like wind turbines, solar panels, batteries, and electric vehicles. The need for these new technologies, however, underscores a fundamental truth: everything that cannot be grown must be mined. The realization has dawned that the materials needed for the energy transition—iron, copper, lithium, nickel, and more—require new mining efforts.

This presents a dilemma for traditional environmentalists: mining, with its environmental impacts, is necessary to combat the broader environmental issue of climate change. In facing the climate crisis, it becomes clear that our approach to environmentalism must evolve. There is no such thing as sustainable mining. Once mined, resources will never go back where they came from and the mine site will never be exactly the same again. The reality is that local and global environmental concerns sometimes clash, and if we recognize this, we can work to ensure that mining evolves to minimize its environmental footprint, and striving towards zero emissions.

Addressing Misconceptions

It's a common belief that the energy transition will demand more mining than our current reliance on fossil fuels. There is a kernel of truth to this: the materials required to manufacture electric cars and onshore wind farms are substantially more than those needed for petrol cars and coal-fired power plants. But manufacturing those products is only part of the story. The reason we’re replacing those technologies is for what comes after the manufacturing, it’s because of the fossil fuels they burn that emit greenhouse gases. We need to consider the entire lifecycle, including the mining required for these fossil fuels. And in this framework, traditional energy sources require far more mining than renewable technologies.

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, or one hundred times less. Furthermore, considering the recycling of battery materials and the fact that most of the metal content is reclaimed, only about 30 kilograms of metals are lost for the average battery, which includes 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 the petrol or diesel that gets burned during a vehicle's average lifespan is around 300-400 times greater than the total quantity of battery cell metals that aren't recovered. 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.

With this in mind, isn’t unfair to target mining associated with energy transition technologies while ignoring mining for fossil fuels? These are undoubtably the bigger problem, not only in terms of the vast bulk of mining needed but also for emissions which due to the significant fugitive methane and CO2 emissions that arise from fossil fuel mining. However, fossil fuel mining will not be a major part of our net zero future. Those emissions are going to reduce as it is phased out. For the future of mining therefore, it does make sense to focus on zero-emission mining for materials crucial to the energy transition.

Emissions in the Mining Industry

Let’s take a look at where emissions come from in mining for the energy transition. First from extraction, then processing, waste management and finally transportation.

The first emissions source associated with extraction is from fossil fuel combustion. That is diesel, petrol, or coal in mining equipment, vehicles, and facilities, or in machinery like drills, excavators, and transport trucks. Plus onsite electricity generation: remote locations are often reliant on diesel generators.

Mining machinery is going electric or possibly using hydrogen. Fortescue are one of the leaders here with electric machinery and a huge 3MW charger in plan for trials to start in 2024. And for onsite electricity generation, many mining sites are finding that using solar and wind plus batteries can vastly reduce the amount of diesel needed and reduce costs. As battery costs come down, mines will be able to get very close to 100% renewable power.

Next, are indirect emissions from offsite (grid) generation of electricity used in mining operations, especially if sourced from coal or other fossil fuel-based power plants, which are tied to progress towards zero-emissions electricity grids. And supply chain emissions from the production and transport of goods and services used in mining operations.

There are also emissions associated with the impact of clearing land for mining sites, which includes the loss of carbon sequestration potential when forests are removed, and the direct release of stored carbon from trees and soil. This is an impact which can likely never be completely solved by technology, however there are some solutions that can reduce the number of new mines needed and the impact of ones that are needed. These include new extraction methods such as direct lithium extraction (DLE) to access lithium brines, which eliminates the need for solar evaporation ponds, salt piles, and lime plants , thus reducing land use and degradation. Remining old mines and tailings for different minerals is another approach to reduce land use and deforestation. This method involves revisiting previously mined areas to extract additional valuable minerals, thereby reducing the need to open new mines. It's a way to utilize already disturbed lands rather than impacting new areas.

Moving on from extraction itself, we get to ore processing emissions. Crushing and grinding, is the most energy intensive process of a typical mine site, making up over half of mining energy use and a huge 3% of the world’s electricity is used on this process. A recent study has shown that alternative crushing technologies can cut energy use by 40%, and smarter blasting techniques can further reduce the energy needed for crushing.

Smelting is very energy intensive, and most of the associated emissions come from burning fossil fuels to reach the high temperatures needed, and as a byproduct of the reduction processs. There are a variety of renewable heat technologies in development that can reach even the highest heats needed for smelting, hydrogen can be used as a reductant without creating CO2, and electrical processes are available to avoid reduction altogether.

There are certain chemical processes used to extract or purify minerals that emit greenhouse gases. The development of new, more efficient methods of mineral separation and purification, which use less energy and produce fewer emissions, is an area of active research. These methods might include advanced membrane technologies, chemical looping, or other novel chemical processes that are more environmentally friendly.

Waste management is needed to preserve the local environment, but has associated emissions. These include from the decomposition of waste materials, particularly in tailing ponds and methane and carbon dioxide emissions from the breakdown of organic materials in waste piles.

Emissions can also arise from the decomposition of carbonate minerals (such as siderite (FeCO3) and calcite (CaCO3)) during weathering and neutralization of waste rock and tailings material, as well as during 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.

Finally, there are emissions from the transport of mined materials to processing facilities or to ports for export which depends on the mode of transport, e.g., trucks, trains, or ships, and their respective emission profiles.

Towards a Sustainable Mining Future

In the face of climate change, mining's paradoxical role has become more prominent than ever. As we've seen, the need for materials in renewable technologies places mining at the heart of the energy transition, despite its environmental impacts. This dual nature represents both a challenge and an opportunity for the industry.

The evolution towards zero-emissions mining isn't just an idealistic goal; it's a pragmatic response to a changing world. As the industry moves forward, the focus on electric and hydrogen-powered machinery, renewable power sources for mine operations, and innovative land use and ore processing methods shows a clear path towards reducing environmental impacts. The shift is already underway, with technologies in development that address the intensive energy demands of processes like smelting and the emissions from chemical extraction and purification.

By embracing new technologies and methods, the mining sector can contribute to a cleaner, more sustainable future, while continuing to supply the essential materials needed for our transition to renewable energy. The path ahead is challenging, but with continued innovation and commitment, mining can play a pivotal role in shaping a sustainable future.