PNNL researchers are developing new instruments that provide a first live look at industrial pollutants reacting with water and minerals
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 CO 2 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.
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.
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.
This work was led by PNNL researchers Zheming Wang, Christopher Thompson, John Loring, and Alan Joly.
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.
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. Photo courtesy of Pacific Northwest National Laboratory.