There is an urgent need for scalable, permanent carbon sequestration strategies to keep global warming to acceptable levels. It is estimated that tens to hundreds of gigatons of carbon dioxide will need to be stored by the end of this century to avoid the worst consequences of climate change. Recent reports by the IPCC and IEA suggest that the yearly amount of geologically‐stored CO2 needs to increase two orders of magnitude by mid‐century. To ensure safe and effective CO2 storage, it is critical to mitigate the risk of CO2 leakage into shallower formations and the surface. Because geologic faults are near-ubiquitous in the subsurface, it is essential to better understand their role in fluid migration, as they can act both as trapping structures—having successfully immobilized hydrocarbons over geologic time—and preferential conduits for migration of subsurface fluids. Forecasting fluid flow within and around faults is difficult because of their inherent heterogeneity and anisotropy, as well as the lack of three‐dimensional measurements of fault properties. Our work is addressing this fundamental knowledge gap through: (1) the development of a new methodology, “PREDICT”, to model sand and clay smearing in the fault core, and estimate fault hydraulic properties such as the permeability tensor and the capillary entry pressure; (2) the implementation of end-to-end workflows to quantify uncertainty and assess leakage risk associated with CO2 storage in geologic formations.
Mineralization – One of the promising strategies is carbon mineralization. In this process, CO₂-rich fluids interact with mafic and ultramafic rocks—rich in divalent cations such as calcium, iron, and magnesium—to form stable carbonate minerals like calcite (CaCO₃), ankerite (FeCO₃), and magnesite (MgCO₃). Once locked away in mineral form, CO₂ is securely stored for millions of years.
However, the reactions that dissolve rock and precipitate carbonates also alter the mechanical strength, porosity, and fluid flow pathways of the host rocks—factors that control how much CO₂ a given site can store. At ERL, our research focuses on these fundamental processes. We design innovative experiments that allow us to directly see carbonate minerals forming within the pore space of basalts at unprecedented resolution. At the same time, we measure key properties such as permeability, acoustic wave velocity, and fluid chemistry to capture how mineralization progresses over time.
By combining these detailed datasets, we are improving predictions of how much CO₂ can be stored in specific geologic settings. This work not only deepens our basic understanding of mineralization processes but also provides practical strategies for monitoring and verifying safe, permanent carbon storage.
Biological Sequestration – Human activity produces huge amounts of waste, such as the 400 million tons of gypsum by-products each year. Only a small share is reused, and billions of tons have piled up in landfills. Equally, organic wastes—like sewage, manure, food scraps, and crop residues—release over 5 billion tons of CO2-equivalent carbon annually.
At ERL, we invented a simple, low-cost microbial method that combines calcium from waste gypsum with carbon from organic waste to lock carbon into stable carbonate minerals. This process combines two environmentally harmful waste streams and generates marketable sulfur while sequestering greenhouse gases. Because infrastructure for organic waste treatment already exists worldwide, the approach could be quickly scaled up to store more than one billion tons of CO2 each year in a safe, long-lasting form.
Image: Pictured is a bubble of CO2 gas trapped by capillary forces in a bed of 0.5 mm diameter glass beads saturated with water; as the CO2 dissolves into the water, an aqueous pH indicator changes from blue to yellow. These are two key mechanisms (capillary trapping and solubility trapping) that securely trap CO2 in deep geologic reservoirs—a technology known as carbon capture and storage (CCS) that can help reduce CO2 emissions during the energy transition. Image courtesy of M. Szulczewski.
