MIT Geophysicists Reveal How Rocks Store Carbon: Revolutionary X-Ray Breakthrough
In a groundbreaking study published today in the journal AGU Advances, MIT geophysicists have unveiled a critical mechanism behind underground carbon storage that could revolutionize climate change mitigation efforts worldwide.
A New Understanding of Carbon Mineralization
To avoid the worst effects of climate change, billions of metric tons of industrially generated carbon dioxide must be captured and stored underground by the end of this century. Rocks offer one of the most promising locations for such massive carbon sequestration.
When carbon dioxide is pumped into underground rock formations, the fluid reacts with the rocks and solidifies into minerals. This process, known as "carbon mineralization," could potentially lock CO₂ into stable mineral form for millions of years without escaping back into the atmosphere.
The X-Ray Discovery
MIT researchers led by study co-author Matěj Peč, associate professor of geophysics, injected fluid into basalt rock samples excavated from a quarry in Iceland and used advanced X-ray imaging to observe how the rocks evolved during mineralization.
"This study gives you information about what the rock does during this complex mineralization process, which could give you ideas of how to engineer it in your favor," says Matěj Peč, an associate professor of geophysics at MIT.
The experiments revealed a surprising finding: as fluid was pumped into the rock, permeability (the ability of fluid to flow through the rock) dropped sharply by more than 95 percent. However, porosity—the rock's total empty space—remained relatively unchanged.
The team discovered that minerals were precipitating out of the fluid in the narrow tunnels connecting larger pores, preventing fluid from flowing into these larger spaces. Despite this, the fluid continued to flow through the rock at a lower rate, allowing carbon mineralization to continue forming in some cracks and crevices.
Practical Implications for Carbon Storage
"If you were injecting CO₂ into the Earth and saw a massive drop in permeability, some operators might think they clogged up the well," adds co-author Jonathan Simpson, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences. "But as this study shows, in some cases, it might not matter if you see a massive drop in permeability."
This distinction is critical for the carbon storage industry. For years, operators feared that low permeability meant wells were clogged and injection efforts were failing. The new research demonstrates that sharp drops in permeability do not necessarily indicate failure.
Why This Matters
Understanding rock behavior during carbon mineralization is essential for scaling up carbon capture technologies. If engineers can predict how rocks will respond to CO₂ injection, they can design better storage systems that maximize efficiency and safety.
The study's findings open new possibilities for optimizing carbon storage strategies. By understanding where minerals precipitate and how they affect flow pathways, engineers can potentially enhance the stability and longevity of underground carbon storage sites.
This research represents a significant step forward in our ability to combat climate change through carbon sequestration. As the world moves toward ambitious carbon reduction targets, technologies like this could help make industrial-scale carbon capture more viable and efficient.