No paradox, no progress

The clean energy paradox is that decarbonising our energy systems means more mining, not less

The fact that waste mine tailings can be used to combat climate change sounds a little confusing at first. How is this supposed to work and, beyond that, all, all over the world?

ARCA: There is a magical type of rock called 'ultramafic' that contains very high levels of iron and magnesium. It originates from deep within the Earth, often from the mantle, which is the thick layer beneath the Earth’s crust. When exposed to air, the magnesium in ultramafic rock binds naturally with carbon dioxide to form new rocks.

Most of the earth’s carbon is stored in rocks. There is enough ultramafic rock, if it were to be exposed to air, to remove a significant proportion of the excess carbon dioxide in the atmosphere. But this would happen very slowly – at geological timescales. Moreover, most ultramafic rock is buried deep underground, where it cannot be used in the fight against climate change.

Some critical minerals are hosted in ultramafic rock. When mining companies are producing nickel, chromium, or platinum group metals, for example, they bring ultramafic rock to the surface. After the critical minerals are extracted in the mining process, the leftover is called 'tailings'. Tailings are then deposited in Tailings Storage Facilities, where they are exposed to the atmosphere. Ultramafic tailings begin immediately to absorb carbon dioxide; creating magnesium carbonate crystals in a process commonly referred to as carbon mineralisation.

Carbon mineralisation results in the permanent return of carbon from the atmosphere back into the geosphere. There is a new industry, called the carbon dioxide removals industry (CDR) that is being built around the imperative established by the UN IPCC to remove between 6 and 16 billion tonnes of CO2 from the atmosphere per year by 2050.

Now, the geology of every mine is different. For those mines working with ultramafic hosted commodities, there is an opportunity to create massive carbon dioxide removal facilities using Arca's technology which accelerates the natural process of carbon mineralisation in ultramafic mine tailings.

Let's assume that critical metal mining all over the world used ARCA technology. What impact could this have on reducing climate-change impact?

ARCA: We estimate that there are 200 billion tonnes of ultramafic mine tailings just sitting on the surface from historical mining practice. This presents an opportunity to permanently remove 40 billion tonnes of atmospheric CO2.

Arca is starting with ultramafic-hosted nickel mines, which in aggregate represents the potential to remove some 30 million tonnes of CO2 per year. Beyond nickel there are other critical minerals, and other industrial waste streams that offer the potential for carbon dioxide removal.

Exploiting all the opportunities for ex-situ (on the surface) carbon mineralisation will result in a meaningful contribution to the emerging global CDR industry, and our collective efforts to rise the challenge of climate change.

Every start-up has a business plan: where does ARCA see itself in 2030 and with what impact?

ARCA: Arca was founded in 2021, after 20+ research at the University of British Columbia. We are now 25 people, headquartered in Vancouver, and we have just launched our first commercial demonstration project in Western Australia. This project will demonstrate the first two of our technologies. In two years we plan to demonstrate our third, breakthrough, technology that we call ‘activation’.

Activation uses high-intensity bursts of energy to disrupt the mineral lattice structure of the ultramafic rock, liberating more magnesium to react with the atmosphere, thereby speeding up the speed and amount of carbon mineralisation that can occur.

By 2030 we plan to be working on multiple mine sites in Australia and Canada, and we plan to be deploying our breakthrough technology across the portfolio. This will result in over 100,000 tonnes per year in CO2 removals.

How can you prove the carbon is stored as a result of your intervention?

ARCA: Proof of permanent removal is a massive issue in the new CDR industry, and Arca has invested significantly in creating a world-leading "monitoring reporting and verification" or MRV system.

Our MRV technologies directly measure CO2 loss from the air above the tailings and quantitatively compare it to the gain of CO2 solid mineral mass in the tailings. Thus, we directly and quantitatively track source (air) to sink (minerals) carbon removal. We have developed a robust method for monitoring CO2 capture and mineralisation in mine tailings using three existing techniques that operate at various temporal and spatial scales.

• We use eddy covariance (EC) towers (measurement area of 1,000s m2 ).
• We also use CO2 flux chambers (measurement area of 10s m2 ) to measure the loss of CO2 from air above the tailings in real time. Agreement between the two methods increases confidence in the overall measurement of CO2 captured from air. We will be using these two methods continuously (24/7).
• The third monitoring technique involves subsampling the tailings at regular intervals (weeks to months) and measuring the increase in total inorganic carbon (TIC) content in the mineral mass of the tailings. Agreement between TIC measurements and EC and chambers demonstrates that the amount of CO2 lost from the air matches the amount CO2 gained in mineral mass, and increases confidence in the total amount of carbon we have captured and stored from source (air) to sink (minerals).

What are the biggest issues (technical, commercial, other) you are trying to solve now in order to scale?

ARCA: Our first commercial demonstration will show that Arca can work in the context of an operational mining operation. We plan to certify this year that we have removed 1,000 tonnes of CO2 in that project. We are working to obtain offtake agreements with buyers of CO2 removals in the voluntary markets; and to establish our second and third demonstration projects on new mines, as well as in our lab to develop the activation technology, so that it will be ready for demonstration in two years.

Every CDR company is different, with different issues and challenges dependent on their 'pathway' for removal. What is common across all the different pathways is this huge sense of urgency.

Humans have never built and scaled a new global industry to trillion dollar scale in the space of two decades before. There is no time to waste.

Do you believe the voluntary carbon removals market will provide a sufficient demand pull or is government regulation a must? What kind of regulations/support do you think are required?

ARCA: That is a very good question. Both are needed.