The capacity to store CO2 underground is much lower than initially thought. This is evident from a study published by the International Institute for Applied Systems Analysis and the Grantham Institute at Imperial College London, which appeared in the journal Nature. Underground carbon capture has long been marketed as a climate solution, as a way out to tackle climate change.
The study found that global carbon storage capacity was ten times less than previous estimates after ruling out geological formations where the gas could leak, trigger earthquakes, or contaminate groundwater, or had other limitations.
That also means that carbon capture and storage would only have the potential to reduce human-caused warming by 0.7 degrees Celsius — far less than previous estimates of around 5-6 degrees Celsius, researchers said.
Safest storage
Especially countries that produce a lot of fossil fuels have the most significant underground storage capacity for CO2 because unused mines provide the most efficient storage.
The safest storage sites are located in Saudi Arabia, Congo, and Kazakhstan, among others, while Norway, Canada, and EU countries are seeing the most significant reductions in their storage capacity. This could also be bad news for Belgium, as in mid-2024, Belgium signed an agreement with Norway for the underground storage of CO2 from Belgian industry.
Climate change
Co-author Joeri Rogelj, the Belgian director of the Grantham Institute for Climate Change and the Environment at Imperial College London, explains that geological storage should be seen as a finite resource that must be managed responsibly to ensure a safe future for humanity. It should be used to halt climate change, not to offset continued CO2 pollution from fossil fuels or outdated combustion engines.
Current climate scenarios project warming of up to 3°C by the end of the century. To mitigate this warming, CO2 storage will likely be necessary, although its area of application will be significantly smaller than initially thought.
Carbon removal and storage
The 2015 Paris Agreement aimed to limit the average global temperature increase to 2 degrees Celsius. Many scenarios for achieving that have relied on carbon removal and storage, assuming the potential was “huge”, but that’s never systematically challenged or tested. So, countries now must prioritize how they use the limited storage and do so in conjunction with fast and deep emissions reductions.
Carbon dioxide, a gas produced by burning fossil fuels, traps heat close to the ground when released to the atmosphere, where it persists for hundreds of years and raises global temperatures.
CCS
CO2 storage involves trapping carbon dioxide emissions, primarily using geological methods, such as injecting CO2 into deep, porous rock formations like saline aquifers or depleted oil and gas reservoirs, and to a lesser extent, mineral storage where CO2 reacts with minerals to form solid carbonates.
This process is a key part of Carbon Capture and Storage (CCS), which aims to mitigate climate change by preventing CO2 from entering the atmosphere.
