Today, CO₂ is permanently stored beneath the seabed. So far, however, little attention has been given to the possibility of using old rock formations for onshore storage close to emission sources. Led by NGI – the Norwegian Geotechnical Institute, Norwegian research and industry partners are now exploring this opportunity.
“Norway is at the forefront of research on CO₂ storage. This is the first project to investigate the possibility of storing CO₂ in geologically old rock formations,” says project manager Bahman Bohloli from NGI about the project MiniCCS: Small-scale local onshore CO₂ storage in mafic & ultramafic rocks.
The three-year research project has a total budget of NOK 14.7 million and is funded by Gassnova together with industry partners Gassco, Equinor, Hydro and 44.01 Norway AS. In addition to NGI, the University of Oslo, the Geological Survey of Norway, and BI Norwegian Business School participate in the project.
Industry-driven initiative
The innovative project originates from requests by industry stakeholders seeking to explore opportunities for smaller-scale CO₂ storage on land, close to where emissions occur.
“At NGI, we have made a map showing where these old geological formations, known as mafic and ultramafic rocks, are located across the country, and how they relate to emission sources,” Bohloli explains.
The aim of the project is to investigate whether onshore CO₂ storage is technically feasible and whether it can be cost-effective and environmentally sound.
The map, developed by NGI, shows emission sources and the locations of old geological formations that may potentially be used for CO₂ storage in the future.
Is there storage capacity? Can the rock still capture CO₂?
As researchers begin studying and analysing the old rock formations in the field and in laboratories, several key questions must be addressed.
“We need to determine whether there are voids, in the form of pores or fractures in the rock, that provide sufficient volume for CO₂ storage. These pore and fracture sizes can range from microscopic scales to several centimetres. We must also understand whether these old rocks still have the capacity to absorb CO₂,” says Bohloli.
Storage capacity depends on chemical reactions between CO₂ and rock. If the rocks have previously been exposed to CO₂, potentially millions of years ago, their storage capacity may already be used.
“These are questions that no one can currently answer. Through this project, we will test and find out.”
Turning CO₂ into solid rock
In Norwegian folklore, trolls turn to stone when exposed to sunlight. In the “story” of CO₂ storage, it is the rock itself that turns greenhouse gases into stone. This process gives researchers confidence that onshore CO₂ storage can be safe, with minimal risk of leakage or pollution.
“These rock types react with CO₂ by transforming the greenhouse gas into solid minerals. Pilot studies in the United States and Iceland have shown that up to 60 percent of injected CO₂ can turn into stone within two to five years,” says Bohloli.