Water sampling technique paves way for safe storage of CO2

Trials of the method will help the development of Carbon Capture and Storage (CCS) technology

Scientists from the Universities of Edinburgh and Australian research organisation CO2CRC have discovered an inexpensive way to monitor the storage of carbon dioxide underground. Trials will help the development of Carbon Capture and Storage (CCS) technology.

The researchers studied the different forms of oxygen in waters sampled from rocks deep below ground at the storage site in the Otway Basin, in south eastern Australia. They found that the reservoir’s waters changed their oxygen composition when in contact with bubbles of trapped CO2.

Testing samples of water for this altered form of oxygen provides a simple way to measure the amount of CO₂ stored within the rock. The study shows that injected CO2 is very quickly retained in the underground rocks, with CO2 being locked away like air being trapped within a foam sponge.

The researchers said their technique provides an inexpensive monitoring solution, as they need only measure only CO2 injected into a site and water samples from before and after injection to find out how much CO2 is trapped.

Dr Sascha Serno, of the University of Edinburgh’s School of GeoSciences, who led the study, said: “Our results highlight the promising potential of using oxygen compositions to monitor the fate of CO2 injected underground. This method is simple and cheap, and can be easily combined with other monitoring techniques for CCS projects in the UK and beyond.”

The study was published in the International Journal of Greenhouse Gas Control.