CCS involves carbon dioxide (CO2) being captured from industrial sources before it’s injected into deep geological reservoirs – comprising of porous rock – where it’s stored ‘permanently’ (thousands of years).
Despite various capture and utilisation technologies being publicised, less is known about the storage itself.
A researcher at the University of Texas at Austin’s Bureau of Economic Geology, Sahar Bakhshian, has worked using supercomputer simulations to understand how best to optimise the amount of CO2 that is capable of being stored.
The supercomputers, part of the Texas Advanced Computer Center (TACC), allowed Bahkshian to run various scenarios using different injection rates and fluid-rock properties to assess the amount of CO2 that could be stored in the spaces within the rocks.
She found that wettability (how well CO2 molecules stick to the surface of the rock) and injection rate (the speed at which supercritical CO2 is pushed into the reservoir) are two of the biggest factors.
Left: Subsurface CO2 storage. Right: CO2 migration pattern in a digitized rock sample obtained from pore-scale two-phase flow simulation
Capillary trapping – when CO2 pinches off and becomes immobilised in the pore space – also plays a key role in helping keep the gas effectively stored.
Bahkshian’s research is supported by the Gulf Coast Carbon Center (GCCC) and could play an important role in achieving large-scale CCS.
“Computational fluid dynamics techniques are essential for this field, to better screen suitable target reservoirs for CO2 storage, and predict the behaviour of CO2 plumes in these reservoirs,” she said.
The research could accelerate the drive to advance CCS technologies, especially in the US, which – according to the Global CCS Institute – is one of the nations with the greatest potential for geological CO2 storage.
The International Panel on Climate Change (IPCC) has called CCS one of the ways the global community can achieve net-zero emissions by mid-century.
Bahkshian’s full research paper on carbon storage is available here.