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Carbon Sequestration May Not Work Says Study

21.01.2015 17:40 Age: 3 yrs

Plans to store carbon dioxide in the rocks may be on shaky ground, according to research from MIT scientists. This study finds a natural impediment to the long-term sequestration of carbon dioxide

Click to enlarge. Courtesy: Christine Daniloff/MIT


by Jennifer Chu, MIT News Office





CO2 sequestration in subsurface reservoirs is important for limiting atmospheric CO2 concentrations. However, a complete physical picture able to predict the structure developing within the porous medium is lacking. We investigate theoretically reactive transport in the long-time evolution of carbon in the brine-rock environment. As CO2 is injected into a brine-rock environment, a carbonate-rich region is created amid brine. Within the carbonate-rich region minerals dissolve and migrate from regions of high concentration to low concentration, along with other dissolved carbonate species. This causes mineral precipitation at the interface between the two regions. We argue that precipitation in a small layer reduces diffusivity, and eventually causes mechanical trapping of the CO2. Consequently, only a small fraction of the CO2 is converted to solid mineral; the remainder either dissolves in water or is trapped in its original form. We also study the case of a pure CO2 bubble surrounded by brine and suggest a mechanism that may lead to a carbonate-encrusted bubble due to structural diffusion.


Long-time evolution of sequestered CO2 in porous media by Yossi Cohen and Daniel H. Rothman published in the Proceedings of the Royal Society A

Read the abstract and get the paper here.


MIT news release here.