29 DECEMBER 2024 WorldWide Drilling Resource® From Air to Rock Adapted from Information by PNNL Pacific Northwest National Laboratory (PNNL) scientists have developed a process which transforms carbon dioxide (CO2) into solid rock. It mimics earth’s natural processes, but at a much faster pace - from thousands of years to mere months. But storing CO2 in solid minerals, a process called carbon mineralization, at a scale large enough to make an impact, takes more than just the discovery alone. “We need ways to measure, verify, and communicate that the CO2 we put in the ground is mineralized and won’t escape,” said PNNL Chief Chemist Todd Schaef, who pioneered carbon mineralization in basalts. Madeline Bartels, an intern on Schaef’s team, has helped to do that. Her research counts carbon mineral molecules at a scale no one has measured before. “We can actually see how much carbon we’re locking away in rock,” said Bartels. “Imagine putting a playing card on a football field. That would be equivalent to the scale of what one part per million would be, but instead we’re measuring the amount of carbon minerals in a tiny sample of powdered rock.” Although carbon mineralization can lock away CO2 in large quantities, there has not yet been a commercial-scale project in the United States. A special permit to inject CO2 underground is needed, but hasn’t been attained so far because industrial requirements are still being developed and tested. If adopted as a standard, the thermogravimetric analysis mass spectrometry (TGA-MS) technique could one day be used by private companies to measure and verify how much CO2 is being locked away. “It’s really cool that research I was working on as an undergraduate can possibly make a significant contribution to the field as it is emerging,” said Bartels, who has participated in two Department of Energy (DOE), Office of Science Workforce Development for Teachers and Scientists SULI (Science Undergraduate Laboratory Internship) appointments while earning her bachelor’s degree at Yale University. At high heat, various reactions occur. Water molecules and CO2 molecules are released from the sample and enter a small tube, connected to a mass spectrometer. The technique allowed researchers to quantify carbon minerals as they entered the mass spectrometer through the tube. They detected the minerals at a miniscule level of 48 parts per million, the first study known to push TGA-MS quantification down to double digits. Using the measurements, the PNNL team created a calibration curve to link the weight of carbon minerals to their TGA-MS signal, allowing them to quantify the amount of carbon minerals in the sample. Bartels rejoined PNNL this summer as a SULI intern and plans to continue her carbon mineralization and geochemistry research as a graduate student. “Madeline’s participation in SULI gave her the opportunity to learn hands on, publish a paper as first author, and be featured in a cover. It was great, impactful work,” said Quin Miller, a PNNL chemist. “The more people we have on this team, the more perspectives, ideas, and methods are introduced on how to do things to bring this research to scale.” As the research field develops, Schaef and Miller are invested in bringing the PNNL discovery of carbon mineralization to the commercial scale and inspiring students and early career researchers to join the quest for carbon management solutions. Quin Miller talks with his mentee, SULI intern Madeline Bartels. They are standing in front of a high-pressure hydrothermal X-ray diffraction experimental platform used to probe reactions at extreme conditions, including those in the subsurface relevant to carbon mineralization. ENV Geochemists from PNNL, DOE, universities, and industry gathered for the PNNL-hosted Integrated Mineralization Strategy Workshop. Intern Madeline Bartels giving a demonstration of TGA-MS. Photos by Andrea Starr. Booth 633
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