New research shows that carbon dioxide (CO2) emissions can be captured and securely stored beneath deep-seated and impermeable underground rocks.
The findings provide further evidence that a developing technology known as Carbon Capture and Storage (CCS), in which climate changing CO2 gas emissions from industry are collected and transported for storage underground, is safe.
Researchers studied natural CO2 gas fields and CO2 mineral springs in south-east Australia to improve the understanding of how to safely store CO2 underground.
By measuring tiny traces of inactive natural gases, known as noble gases, found in the CO2 they were able to show that, in both the gas fields and mineral springs, the CO2 had come from the same source, the Earth’s mantle.
The Earth’s mantle is around 40 kilometres below the depth where the samples were collected from. Despite such a long distance of travel, the unique noble gas signature preserves the record of the gas origin. The same techniques can therefore be confidently applied for monitoring injected CO2, where travel distances are much shorter than in these natural samples.
Dr Rūta Karolytė, who led the research at the University of Edinburgh said: “We were able to show for the first time that noble gases remain very sensitive tracers of the source of CO2 even after it mixes with large volumes of water. This means that we can use noble gas techniques to sensitively fingerprint stored CO2 once it is injected underground.”
Dr Stuart Gilfillan, who directed the study said: “Our work clearly shows the unique capability of using noble gases to monitor CO2 injected for geological storage. This paves the way for safe storage of CO2 in old gas and oil fields, such as those present in the North Sea.”
Such an approach can reduce emissions of CO2 and help to limit the impact of climate change. Adoption of CCS technologies could greatly help the UK cut its greenhouse gas emissions to almost zero by 2050, necessary to meet recently announced targets.
The study, published in Geochimica et Cosmochimica Acta, was supported by the UK Engineering and Physical Sciences Research Council and the Australian research organisation CO2CRC. The paper is available for 50 days.