Scientists to Store Carbon Dioxide Underground to Reduce Negative Impacts of Climate Change
Scientists are now planning to capture carbon dioxide from the atmosphere and store it underground to reduce carbon emissions from coal and gas-fired power stations, potentially thwarting negative effects of climate change.
A new study, published in the journal Nature Communications, showed that the carbon capture and storage (CCS) process is possible and that the carbon emission needs to be stored underground for at least 10,000 years to prevent climatic impacts.
During the CCS process, carbon dioxide produced at power plants is captured, compressed and pumped into reservoirs in the rock more than a kilometer underground. In order to be truly effective, impermeable cap rocks are needed to trapped the carbon dioxide in the reservoir and avoid the stored carbon dioxide to spill back to the atmosphere.
Previous studies suggests that CO2-charged brines formed as carbon dioxide dissolves in water might progressively corrode cap rocks, resulting to a weaker and more permeable layers of rock several meter thick, which could jeopardize the secure retention of CO2.
To determine if cap rocks can potentially seal off carbon dioxide underground, researchers from the University of Cambridge examined a natural-occurring 100,000 year-old reservoir of carbon dioxide. With the help of some experts, the researchers drilled deep down below one of the natural reservoir and collected samples of the rock layers and the fluid contained in the rock pores.
According to a press release, the corrosion of the materials comprising the rock sample was studied using acidic carbonated water. The researchers also analyzed the mineralogy and geochemistry of the cap rock. To better understand the changes that may have occurred in the pore structure and permeability of the cap rock, the researchers bombarded the sample with neutrons.
The researchers discovered that the carbon dioxide trapped in the reservoir has a very little impact in the corrosion of minerals in the cap rock, with the corrosion limited to a layer only seven centimeters thick. Their results is much lower than the predicted corrosion in previous studies.
Their findings suggest that minerals in cap rocks are capable of resisting acidic carbonated water, proving that the CSS process is much more predictable and safer than releasing carbon dioxide in the atmosphere.