A research team led by Professor Yongwon Seo from the Graduate School of Carbon Neutrality at UNIST has successfully elucidated the replacement behavior and mechanisms associated with varying concentrations of carbon dioxide (CO2) in guest replacement technology for natural gas hydrates (NGHs).
Their research also proposes the optimal concentration of injected gas mixtures to maximize natural gas production while enhancing CO2 capture. This guest replacement process facilitates the extraction of natural gas from NGHs and its replacement with CO2, a known greenhouse gas.
The team conducted experiments using flue gas—also known as exhaust gas or stack gas—a mixture of nitrogen (N2) and CO2 emitted from industrial combustion processes, such as those in power plants and boilers. Utilizing this flue gas for injection allows for direct introduction of CO2 into NGH layers without the need for prior CO2 separation. However, because N2 occupies space within NGHs instead of CO2, further investigation is warranted to optimize this process.
In this study, the dynamics of gas guest distributions in the CH4–flue gas replacement process were explored. Systematic analysis revealed a trade-off where increased concentrations of N2 not only delayed the rates of CO2 storage but also CH4 production.
The research team measured replacement behavior, natural gas production, and CO2 storage using various concentrations of flue gas, ultimately discovering a correlation equation linking the concentration ratio of CO2 stored in gas hydrates to the concentration of the injected gas. Their findings indicate that natural gas production and CO2 storage efficiency are optimized at a CO2 concentration of 64%.
“The results of this study are expected to provide guidelines for utilizing natural gas hydrates, which are distributed around the world, as reservoirs for greenhouse gases and as sources of clean energy,” said first author Dr. Junghoon Mok from UNIST, who is currently Assistant Professor at Kyonggi University.
Researchers Jonghyuk Lee and Wonjung Choi also contributed to this study. The findings were published in Renewable & Sustainable Energy Reviews.
More information:
Junghoon Mok et al, Complementary and competitive dynamics of CO2 and N2 in CH4—Flue gas replacement within natural gas hydrates, Renewable and Sustainable Energy Reviews (2024). DOI: 10.1016/j.rser.2024.114971
Citation:
Study unveils the optimal concentration for effective CO₂ capture in gas hydrates (2024, November 18)
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