The European Commission is counting on it. The government’s Climate Program rests on it. And the UN’s Intergovernmental Panel on Climate Change (IPCC) claims that there is no way around carbon capture and storage.
In fact, in its latest report from April this year, the IPCC underlined the fact that we will have to capture CO2 from the atmosphere if we are to keep global warming anywhere near the 1.5 degrees Celsius from the Paris Agreement.
In practice, this means that we need various technologies for carbon capture and storage.
The Danish contribution to slowing global warming is, among other things, the Climate Act’s 70 percent target for 2030. To reach it, we need to reduce greenhouse gas emissions by 10 million tonnes of CO2 equivalents (CO2e) within the next eight years.
According to the government’s Climate Program 2021, this must be achieved, among other things, by storing CO2.
But how realistic is that? Are there mature carbon capture and storage technologies, or is Dan Jørgensen’s “hockey stick” model—expecting that the reduction of CO2 emissions will initially follow a curve that is as flat as the shaft of a hockey stick, until technological solutions at the last moment cause the curve to rise sharply and hit the mark—still a joke?
Through a review of scientific and political reports, as well as interviews with Danish researchers and experts, Ingeniøren has identified the carbon storage tools available to Denmark and assessed their technological maturity.
They can be divided into five general categories: biological storage with afforestation as an active measure, underground geological storage on land and at sea, storage in biochar produced from pyrolysis of biomass, storage in buildings (with wood-based materials as a good example), and mineral storage, where CO2 reacts with different types of minerals in a process called carbonation.
By comparing the various tools available, Ingeniøren came to the conclusion that there are both mature and immature technologies. However, they all have one thing in common—it takes time to implement them.
In other words, carbon capture and storage is one of several necessary fixes when it comes to climate change—but hardly a quick one.
Afforestation is the most mature of the possible storage methods, but the disadvantage is that it takes years from making a decision to seeing an effect. It is quite simply because it takes time for trees to grow, and they can only capture a significant amount of CO2 after a decade.
A forest planted today will therefore only really contribute to the 70 percent target after 2030. There is also the issue of space—trees compete with both food and energy crops.
The limited space therefore places a limit on how much atmospheric CO2 can be captured via photosynthesis. In fact, lack of space is a problem that affects several carbon capture and storage technologies.
In addition to afforestation, both wood-based construction and biochar storage require quite a lot of space, and the gain of capture from flue gases with subsequent geological or mineral carbon storage is greatest if the captured CO2 comes from burning biomass.
Carbon capture and storage as an emission reduction strategy therefore also requires a well-considered political decision on the distribution of land.
The second most mature of the technologies—geological storage—also requires a timely political decision.
The government itself says in its Climate Program 2021 that a decision must be made by 2025 at the latest on massive investment in underground carbon capture and storage if it is to have an impact on the 2030 target.
A decision which, according to several of Ingeniøren’s sources, would be quite sensible. The storage technology itself is well understood, and there is low-hanging fruit to be picked by storing CO2 captured by upgrading biogas. The Danish Energy Agency expects a storage potential of 1.5 million tonnes of CO2 annually in 2030 from biogas alone.
There is also the ongoing public tender for CCUS (carbon capture, utilization and storage) worth DKK 8 billion, which will ensure the capture and storage of 0.4 million tonnes of CO2 annually already in 2026. At the same time, we have carbon storage projects, such as Bifrost and Project Greensand in the North Sea as well as Gas Storage Denmark’s onshore project, which, if successful, will be able to store at least 5 million tonnes annually from 2030, according to Ingeniøren’s sources.
“Capture from large point sources and geological storage, I have no doubt, is one of the methods that will work the fastest,” says Erling Halfdan Stenby, professor and head of department at DTU Chemistry and vice chairman of the InnoCCUS partnership for carbon capture, utilization and storage.
But even though geological storage may be available and effective in good time, it is not sufficient to bet everything on capture at point sources and subsequent geological storage. We do not need just a single method of storing CO2, but a whole range of them, according to several of our sources.
“I’m of the opinion that we have to do it all,” as Erling Halfdan Stenby says.
And to have all of the capture and storage tools, a broad effort must also be made to reduce human consumption in general and to promote a complete transformation of the energy supply. That message is repeated time and time again by the Danish Council on Climate Change, the IPCC, and scientific reports, as well as roadmaps for the recovery of the global climate.
Even with reasonable options for a large range of carbon capture and storage technologies in the long term, we need to reduce emissions to achieve neutrality.
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