For the first time, researchers have investigated the possibility of storing carbon dioxide in Sweden’s onshore bedrock. In a new study from Luleå University of Technology, two locations have been identified where the bedrock has the potential to transform carbon dioxide into rock by mineral carbonation.
According to the study “Permanent storage of carbon dioxide in mafic rock formations: exploring Sweden’s potential“, published in the scientific journal Frontiers in Climate, these locations are Sundsvall and Örnsköldsvik.
The study is part of the Utilization of industrial residues for an efficient geological BECCS (INSURANCE) project investigating the potential for onshore storage of carbon dioxide from the industry in the Swedish bedrock.
The researchers examined around twenty sites, stretching from Kalix in the north to Kalmar in the south.
The results show that the bedrock around Sundsvall and Örnsköldsvik has the potential to store carbon dioxide (CO2). The volcanic rock in these areas has the right composition to react with CO2 and bind it.
We have identified bedrock in Sweden that, in theory, is suitable for onshore carbon storage. This has not been done before, and it is an important first step. We have now moved on to carrying out experiments to see how effectively these rock types can bind and store carbon dioxide, said Emelie Crafoord, Doctoral Student in Ore Geology at Luleå University of Technology and co-author of the report.
Sundsvall and Örnsköldsvik are also two locations where pulp mills emit large volumes of biogenic carbon dioxide (bioCO2)
We chose to investigate sites located close to emission sources, as this reduces the need for transportation. We urgently need to find ways to cut emissions. Capturing and storing carbon dioxide alone won’t be enough to meet global climate goals, but it can form part of the solution, said Emelie Crafoord.
Collaboration with Iceland
Storing carbon dioxide in volcanic bedrock involves capturing CO2, dissolving it in water, and injecting it into the rock.
The acidic liquid reacts with the bedrock to form carbonate minerals – in other words, the carbon dioxide turns into stone.
In Iceland, facilities already use this method. Iceland’s geologically young and porous bedrock is well suited to the purpose, and it takes around two years for the CO2 to turn into stone.
Researchers at Luleå University of Technology are collaborating with Icelandic scientists and believe the technique could also work in Sweden, although the Swedish bedrock will react more slowly since it is much older than Iceland’s.
Advantages of storing on land
Much of today’s carbon storage involves injecting CO2 into sedimentary rock formations beneath the seafloor, but there are several advantages to storing it on land.
In seafloor storage, it takes thousands of years for the carbon dioxide to convert from liquid to solid form. In volcanic bedrock on land, this transformation happens much faster, and the trapped carbon dioxide remains stable and permanently stored deep within the bedrock. Other advantages of onshore storage include lower transport costs and easier, cheaper monitoring of the CO2 until it has fully mineralised, said Glenn Bark, Senior Lecturer in Ore Geology at Luleå University of Technology and co-author of the paper.
Carbon capture and storage is part of the solution
In addition to ongoing work examining how quickly Swedish bedrock can react with carbon dioxide, other challenges remain.
At present, onshore carbon storage in Sweden is only permitted in small quantities for research purposes.
Beyond assessing the potential for storage, we also need to understand any possible environmental impacts the technology might have. We need legislation that allows onshore storage, and we need further research into the bedrock. If we can capture and store part of our emissions, that’s a step in the right direction, while it’s equally important to emphasise that society’s emissions must decrease. Carbon storage should be seen as a complement to large emission reductions, concluded Glenn Bark.
