Carbon-Free Mining Revolution

Esti Ukar is a research scientist at the Bureau of Economic Geology at the Jackson School of Geosciences. She earned her Bachelor of Science in geology at Euskal Herriko Unibertsitatea/ Universidad del País Vasco in Spain in 2003 and her doctorate in geological sciences at the Jackson School in 2010. Ukar is leading a project to develop technology for mining critical minerals — mineral resources that are essential to the economy and whose supply may be disrupted — more efficiently and without adding any carbon dioxide to the atmosphere. The three-year, $5 million project is part of the Department of Energy’s (DOE) Mining Innovations for Negative Emissions Resource Recovery (MINER) program, which aims to develop market-ready technologies that will increase domestic supplies of critical elements required for clean energy technology.

Q&A with Esti Ukar

By Anton Caputo

Q: Tell us a little bit about the project. Why is it important to decarbonize mining?

A: As you probably know, there is an urgent drive to develop lowcarbon emission energy technologies and sources of energy all over the world. A major element of this effort is using electric vehicles instead of vehicles that burn gasoline. But the batteries that power these vehicles require lots of lithium, nickel, cobalt and other elements that are in low concentrations in the Earth’s crust and are often referred to as “critical minerals.” Mining these takes a tremendous amount of energy and produces significant CO₂ emissions and other negative environmental impacts, which is exactly what we’re trying to avoid. That’s what we’re trying to address.

Q: You are trying to make these mining operations carbon free or carbon neutral?

A: Yes, carbon neutral or better yet, carbon negative. If you are able to capture and store all the CO₂ produced during the mining operations, that makes it carbon neutral. We want to go beyond that and capture even more carbon, making the operation carbon negative. That means in addition to storing the CO₂ from the mining operation, we would be able to take CO₂ from other industrial sources and store it underground too.

Q: Can you explain how the CO₂ storage process works?

A: Storing CO₂ underground so it is not released into the atmosphere is an issue that we have been working on at the bureau for decades. In this project, we plan to inject a solution of water and CO₂ into ultramafic rock containing critical minerals. This solution helps partially replace the ultramafic rock with softer carbonate and pre-fracture the rock. Breaking and weakening the rock’s structure is expected to reduce energy requirements for crushing and grinding the critical mineral ore. At the same time, the CO₂ in the solution reacts with magnesium, iron and calcium that is also in the rock. This reaction leads to the CO₂ being incorporated into the rock’s mineral structure — permanently storing it. In addition to offsetting the mine’s emissions, the CO₂ storage process could also be eligible for federal CO₂ credits, which could help make mining critical minerals more affordable and lead to greater production throughout North America.

Q: Where do you plan on doing this project?

A: We will spend the first two years perfecting the process in the lab before taking it to the field. We particularly want to work on finding ways to make the reaction that stores CO₂ in ultramafic rock faster. Instead of geologic timescales, we need to make the reactions occur within weeks to months for the process to be economically viable for mining. The research will also involve computer modeling and determining the best CO₂-H₂O cocktail, pressure-temperature conditions and rates of injection. After perfecting the method in the lab, we will conduct a full-scale field test in partnership with Canada Nickel Company in one of 20 newly discovered ore bodies near the U.S.-Canada border thought to be an important new source of critical minerals in North America.

Q: Has this been done before?

A: Not in ultramafic rock like we are proposing to do, mostly because ultramafic rocks have low permeability that make it difficult to get the fluids in. But we believe we have found a way to make it work. There is a project in Iceland called CarbFix that has been storing carbon in basalt for years. It’s a different type of mafic rock and there is no mining associated, but the method is similar. In fact, Dr. Sandra Ósk Snæbjörnsdóttir, who is the head of CO₂ mineral storage for CarbFix, is collaborating with us on this project.

Q: You are leading a large multi-disciplinary team in this project. Can you tell us who is involved?

A: We have several areas of the Jackson School involved, both here at the bureau and in the Department of Geological Sciences. These include the bureau’s Gulf Coast Carbon Center, which is a world-leading organization in perfecting and monitoring carbon storage to make sure it is safely stored. We also have experts from TexNet, the state’s seismic monitoring system that was created by is managed by the bureau, to help determine if the mining operations will cause any seismic activity, including microseismicity that can be used to monitor the progression of carbonation. We also have researchers from the UT Department of Petroleum Geosystems Engineering, Aerospace Engineering, Columbia University, the University of Bern and CarbFix. It’s a large team, needed to tackle a large task!

Q: What is the ultimate goal for this research? Are you hoping this can be applied widely?

A: Yes, the funding agency is DOE’s Advanced Research Projects Agency-Energy, which is focused on creating marketable technologies. Our combined goal is to transform the mining industry. The urgency to find a sustainable, national supply of critical minerals is such that we have recently received an additional $1 million from DOE’s National Energy Technology Laboratory to find places in the U.S. where this and other sustainable mining technologies could be applied. Our technology will not only be useful in the U.S. but in mining operations globally.

Q: Tell me a little bit about your background. How you are applying it to the project?

A: You never know how different aspects of your life that you once thought were completely unrelated can conspire to come together in unexpected ways. I started my life as a geologist working on hard rocks in subduction zones. Then completely changed topics and continued to work on fractured sedimentary rocks, but unfortunately, didn’t get to work on these deeper, crystalline basement type rocks as much as I would have liked to. That is, until this project came about. It’s the perfect combination of my favorite ingredients: hard rocks, fractures, and trying to change the industry for a better, more sustainable and climate-friendly future. I’m incredibly excited.