The vessel Ocean Surveyor has 41 years on its back – and yes, it shows in some places. A little rust here, worn mahogany there. Heavy leather furniture that breathes the 80s.
But here, you'll also find state-of-the-art measurement and navigation equipment. With a margin of error of just one centimeter, the GPS can determine the boat's position.
Knife-sharp clarity
When we step on board for a shorter trip to Beckholmen in Stockholm's archipelago, where the Vasa sank on its maiden voyage in August 1628, it's hard not to let your thoughts fly away to science fiction movies.
With an underwater camera with knife-sharp clarity, Björn Bergman, head of the marine operations and technology unit at SGU, shows us the spot where the royal ship lay on the seabed for 333 years.
2022, all the technology on Ocean Surveyor was replaced, Bergman explains.
He brightens up.
Look there, he says, pointing to one of the many large computer screens.
A crab.
The little crustacean seems, however, to be moderately interested in being in the spotlight at a depth of about 35 meters and quickly disappears from view.
Searching for porous layers
Ocean Surveyor's equipment is not, however, used daily for this type of pleasure cruise. On behalf of the government, SGU is currently investigating the possibilities of carbon dioxide storage in the bedrock – and then the vessel's measuring instruments are crucial for mapping.
In two areas, in southeastern Östersjön near Gotland and in the sea area south of Skåne, the geological conditions are being examined.
Geological storage of carbon dioxide involves using porous layers in the bedrock to store the carbon dioxide, which is a way to reduce emissions. You take the carbon dioxide that we ourselves produce and pump it down into the bedrock, into the porous layers, says project leader Sofie Lindström.
It works so that if you have a porous layer, for example, sandstone, deep down in the bedrock, there are small spaces between the sand grains. In those spaces, you can store carbon dioxide.
If the sandstone is at a depth of over 800 meters, the carbon dioxide takes up 300 times less volume than it does at the surface, due to the pressure and temperature, she explains.
At that depth, the carbon dioxide becomes supercritical, it behaves both as a liquid and as a gas. At the storage site, the porous layer must be overlaid with dense layers, such as claystone, so that the carbon dioxide is prevented from moving upwards.
And that's exactly what SGU is looking for, by examining the bedrock under the seabed. Because on land, it's not allowed to store carbon dioxide according to Swedish law.
In order for us to be able to do this safely, we need a storage site that is geologically safe, preferably with an upwelling in the bedrock. Then the porous layer is bounded on the sides by the dense layer above. We call it traps. Such traps could be suitable places where you can inject carbon dioxide.
Ways to reach the goals
Sofie Lindström is hopeful that SGU will find usable storage sites. In March 2026, the final report will be submitted to the government, and then she believes it may take about five years before carbon dioxide storage in the bedrock can become a reality.
In Denmark, they have been far ahead in their investigations and have potential storage sites both on land and under the sea.
Their investigations began in earnest in 2022, but they had a good foundation since before. Now they have started issuing licenses to companies that want to investigate the possibilities on land. At sea, they have leftover oil reservoirs where they can store carbon dioxide, and there they plan to start storing from the turn of the year, she says.
Lindström continues to explain – she is engaged and says she can talk for hours about the subject.
It won't go as fast for us because we don't have the same foundation from the start, and we don't have empty oil reservoirs to start from. If we can point out a number of potential sites, it will likely take a few years before it becomes possible to geologically store carbon dioxide in Sweden.
You can't inject into places where there are large cracks in the rock, so that's something we're looking extra at. We also have to think about the fact that there is already water in the porous layers, which means we can't inject the carbon dioxide too quickly, or the pressure will increase, which can lead to cracks in the overlying rock.
Requires monitoring
This could lead to leaks. Therefore, geological monitoring of future storage sites will also be required.
Storing carbon dioxide in this way could be a way for Sweden to reduce the problems of reaching future emission targets. The government has stated that Sweden must have net-zero emissions by 2045 at the latest.
There has been talk of carbon dioxide storage for many years, in varying forms due to the political situation. Since 2023, we have been working on this assignment, and it looks promising. We have found geological layers with high porosity and that exist at sufficient depths. Now we're starting to look at specific sites where these layers exist under the right geological conditions, says Lindström.
Mikael Widerberg/TT
Facts: Carbon dioxide storage
TTTT
The EU has set a goal to be climate-neutral by 2050, and Sweden has set a goal to have net-zero emissions by 2045 at the latest. Separation and storage of carbon dioxide are important puzzle pieces to reach the goals.
The Swedish Geological Survey (SGU) is investigating, on behalf of the government, the conditions for carbon dioxide storage in two areas, in southeastern Östersjön near Gotland and in the sea area south of Skåne.
Source: SGU
