Tracking technique could help keep captured CO2 stay underground

Geological storage is a popular potential option for storing carbon dioxide captured from industrial processes or combustion related to electricity generation; the idea is to pump the gas into depleted natural gas wells or other naturally occurring subterranean geological structures.

However, the security of this technique depends on being certain that the injected gas remains where it is supposed to be and does not migrate through the geology. To date, no method has been found to accurately distinguish injected CO₂ from natural sources of the gas.

Building on previous research that suggested chemical tracers could be added to the injected CO₂ , a team at the University of Edinburgh, one of the partner institutes of the research partnership Scottish Carbon Capture and Storage, undertook research to try to clarify one of the problems with the technique: a poor understanding of how such tracers would move below ground.

In the journal Chemical Geology, a team led by Dr Rachel Kilgallon of the University’s School of Geosciences describes how it used mass spectroscopy to conduct time trials of how different chemical tracers, including noble gases and sulphur hexafluoride, a standard tracer compound used in industry, percolate through sample different porous sandstones.