Carbon capture underground? X-rays test CO2 storage in volcanic rocks

The article discusses a new study from MIT that investigates how carbon dioxide (CO2) can be stored underground in volcanic basalt rocks through a process called carbon mineralization. This process involves CO2-rich fluids reacting with elements like iron, calcium, and magnesium in basalt to form stable carbonate minerals, effectively locking carbon away for millions of years. Basalt is considered a promising storage medium due to its porous nature and mineral content, with pilot projects like Iceland’s CarbFix demonstrating that over 95% of injected CO2 can mineralize within two years. However, scientists have sought to better understand how the rock’s internal structure changes during mineral formation. To explore this, the MIT researchers conducted laboratory experiments using basalt samples from Iceland, injecting mineral-forming fluids while monitoring changes with X-ray CT scanning. The imaging revealed that mineral formation primarily clogs tiny microfractures connecting larger pores, significantly reducing the rock’s permeability (fluid flow capacity) but only minimally decreasing porosity (pore space). Despite the reduced