Storing Industry’s Carbon Dioxide in Real Time

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Photo courtesy of Pacific Northwest National Laboratory

These instruments use ultraviolet and mid- and near-infrared spectroscopy to give scientists vital insights into the reactions between scCO₂ and the water and minerals commonly found in geologic structures considered for CO₂ storage.

PNNL is developing a suite of one-of-a-kind instruments that will allow researchers to probe geochemical reactions under supercritical pressures and temperatures. Scientists can for the first time identify in real time what happens when liquid-like carbon dioxide (CO₂) from power plants is injected into and stored within deep geologic formations.

Why it Matters

The global demand for energy is projected to rise by 57% in less than 20 years.  A large part of the energy sources is expected to be from oil-, coal-, and natural gas-combustion, thus resulting significant increase of CO₂, a major greenhouse gas, in the atmosphere.  One of the strategies currently under consideration for reducing anthropogenic CO₂ emission into the atmosphere is post-combustion capture at fossil-fuel plants followed by injection of the CO₂ into deep geologic formations as a liquid-like supercritical fluid (scCO₂).  To store CO₂ safely, we must know what happens when the water and minerals in a geologic storage reservoir are exposed to liquid-like CO₂ from a power plant. Without these new devices, scientists would have no effective means to study the CO₂ mineral interactions, making scientific investigations more costly.

Methods

Little is known about the physical and chemical processes that occur with scCO₂ and water at solid-liquid and liquid-liquid interfaces. The scientific community also lacks the necessary experimental infrastructure to address these complex issues. To address these deficiencies, PNNL developed two instruments to give scientists vital insight into the reactions. The first instrument uses ultraviolet and mid-infrared spectroscopy to analyze scCO₂ and provides molecular-level information about the interactions/reactions between CO₂, water, and various minerals. Scientists found that the amount of water greatly influenced silicate mineral dissolution and transformation into carbonate minerals, key for selecting geologic sequestration sites.

The second instrument is a portable platform that holds samples at specific temperatures and pressures. With its portability, it can be coupled with several types of spectrometers in the laboratory to gather information on the chemical composition, structure, and electronic properties of water, minerals, and CO₂ as they interact in real time.  Without this system, each instrument would require separate expensive modifications to handle the high pressures and temperatures associated with geologic sequestration.

What’s Next

The development of this spectroscopic platform is advancing our understanding in chemical processes that are key in the interactions between minerals, scCO₂, and saline waters. PNNL’s research team is using these instruments to analyze further the interaction of scCO₂ with a large suite of minerals and rocks, including basalt and shale, from potential CO₂ storage sites. 

Acknowledgments

This work was led by PNNL researchers Zheming Wang, Christopher Thompson, John Loring, and Alan Joly.

Publications

Loring JS, CJ Thompson, Z Wang, AG Joly, DS Sklarew, HT Schaef, ES Ilton, KM Rosso, and AF Felmy. 2011. "In Situ Infrared Spectroscopy Study of Forsterite Carbonation in Wet Supercritical CO₂." Environmental Science and Technology 45(14):6204-6210.

Loring, JS, CJ Thompsonris, C Zhang, Z Wang, HT Schaef, KM Rosso. 2011. “In Situ Infrared Spectroscopic Study of Brucite Carbonation in Dry to Water-Saturated Supercritical Carbon Dioxide.  Journal of Physical Chemistry A, submitted.