|Gareth Johnson and Sascha Serno operating sampling equipment at the CO2CRC Otway site|
Scientists have found an inexpensive way to monitor the storage of the most common greenhouse gas – carbon dioxide (CO₂) – deep underground.
Successful trials of their method at a site in Australia will inform the development of Carbon Capture and Storage (CCS) technology, in which CO₂ from power stations and industrial sources is held deep underground, to prevent emissions from contributing to climate change.
In the first experiment of its kind, 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 research was carried out by SCCS partner institute, the University of Edinburgh, and Australian research organisation CO2CRC.
Researchers say 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.
The study, published in the International Journal of Greenhouse Gas Control, was supported by the UK Carbon Capture and Storage Research Centre and CO₂CRC.
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.
Dr Stuart Gilfillan, also of the School of GeoSciences, the study co-ordinator, said:
Understanding the fate of CO₂ injected into the underground for storage is essential for engineering secure CO₂ stores. Our work with our Australian partners paves the way for better understanding of the fate of CO₂ when we inject it underground.
|Stuart Gilfillan measuring gas samples in the geochemistry lab at CO2CRC Otway site|
This story was published by the University of Edinburgh on 12 July 2016