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Technical CO2 sinks





1.5-degree Paris target only achievable with CO2 cuts

To reach the 1.5-degree target of the Paris Climate Agreement, it is not enough to reduce greenhouse gas (GHG) emissions as much as possible. GHG neutrality will only be achieved if CO2 is also removed from the atmosphere. Natural CO2 sinks are subject to a high degree of uncertainty. Technical sinks are often met with mistrust. As part of a dena study, Prognos examined the current state of knowledge on technical CO2 sinks as well as the entire value chain from CO2 capture and transport to the use and storage of CO2.

Technical CO2 sinks: Areas of application  

Technical CO2 sinks are created when biogenic or atmospheric CO2 is captured and removed from the atmosphere in the long term.

The energetic use of biomass and the subsequent capture of the biogenic carbon (BECCS) is particularly suitable for processes in the industrial sector that have a large, concentrated heat demand at a high-temperature level (e.g. iron & steel and basic chemicals). Here, the specific costs for the entire value chain are currently between 115 and 145 euros/tCO2.

The direct capture of CO2 from the atmosphere with subsequent storage (DACCS) or use in long-life products (DACCUS) holds great potential for negative emissions in the long term. However, sufficient renewable energy and free land must be available for this. The current capture costs of around 700 euros/tCO2 are also very high, so there is still a considerable need for research and development. However, upscaling will be necessary anyway for the production of carbon-based power fuels (P2X), which could be a driver for a faster market ramp-up.

Fossil CO2 emissions from energy use as well as CO2 process emissions that can be eliminated by a technology change should be avoided. In the case of unavoidable process emissions (e.g. in cement production), CO2 capture is necessary from the current perspective. Carbon capture and storage (CCS) is used as CO2 avoidance technology, but no negative CO2 emissions are generated.

The technical prerequisites for the development of a transport infrastructure for CO2 transports are available. However, due to long planning periods, the development would have to begin promptly so that sufficient transport capacities are available if CO2 is to be captured and stored in large quantities. In the medium term, transport by ship is the most cost-effective option. In the long term, a Europe-wide CO2 pipeline infrastructure should be developed.

As far as the utilization of CO2 is concerned, the potential for chemical use is particularly high but also poses major challenges. The use of biogenic or atmospheric CO2 in durable products (e.g. building materials) can make a relevant contribution to climate neutrality, but the potentials here are significantly lower than for chemical use.

The geological capacities for storing CO2 are theoretically very high. The technologies for storage are also available and the costs are relatively low at 4-20 euros/tCO2. However, the limited annual feed-in capacities and the lack of acceptance due to possible risks set limits to geological CO2 storage.

Technologies for technical CO2 sinks are available – but there is a need for technological development and political action

"Overall, the report shows that the technologies are available in the relevant areas. Nevertheless, there is still a high need for research and development for more efficient and mature technologies," says Prognos project manager Sebastian Lübbers. The future potential of technical CO2 sinks depends on the availability of renewable energies, the sustainable biomass supply and the annual CO2 transport and feed-in capacity. For this, the political framework conditions must also be created to guarantee planning security for the stakeholders. Monetary incentives should be created for the large-scale generation of negative emissions. In addition, the social discourse on the necessity and risks of storing CO2 and negative emissions should be forced to create broad acceptance for these topics.

"The focus must remain on reducing GHG emissions. Nevertheless, it is of importance to develop a ramp-up path for technical CO2 sinks in the medium term to generate large-scale negative CO2 emissions in a cost-optimised way in the long term," Sebastian Lübbers emphasises. For the period after 2045, the importance of technical CO2 sinks will increase again to permanently reduce the CO2 concentration in the atmosphere and achieve net negative emissions in the long term.

On 16 June 2021, Sebastian Lübbers spoke at the dena colloquium " The importance of CO2 sinks", Sebastian Lübbers presented the results of this special report in a keynote speech.

To the report (, in German)

Authors: Sebastian Lübbers, Christoph Thormeyer, Jens Hobohm, Hans Dambeck

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