Handling CO2

In the case of petrochemical processes and the production of syngas, carbon capture has been considered state-of-the-art for some time now. But carbon capture is also being further developed in many other industrial processes and the first facilities are being tested or are already in use. 

On the one hand, CO₂ can accrue selectively in higher concentrations in so-called point sources such as cement works. On the other hand, CO₂ may also occur diffusely, i.e. it disperses directly into the air – as in the case of agriculture or air travel. If the formation of carbon dioxide cannot be prevented, it has to be compensated, i.e. it must be captured in another place. This is the only way to meet the goal of climate neutrality. There are several ways to do this:

• Reforestation: when new woodlands are planted they bind CO₂.
• BECCS (Bioenergy with Carbon Capture and Storage): CO₂ is captured in bioenergy applications and then stored by geological sequestration.
• DAC (Direct Air Capture technology): This method captures carbon directly from the ambient air. The extension of this, DACCS (Direct Air Carbon Capture and Storage), further refers to the subsequent storage of the carbon that is captured. This process is, however, extremely energy-intensive. It is therefore more advantageous to avoid CO₂ or to separate it in a more energy-efficient way in areas where it occurs in higher concentrations.

Capturing CO₂ at point source only makes sense if the CO₂ can be subsequently transported from the source to a carbon sink. This can be done by pipeline or ship, amongst other methods, or by rail or truck in the case of smaller quantities. Pipelines are predominantly the logical choice for industrial point sources, such as cement and lime works, where large quantities of CO₂ constantly arise. These pipelines can be used to transport CO₂ to storage facilities (Carbon Capture and Storage (CCS)) or to facilities that make further use of the carbon (Carbon Capture and Utilisation (CCU)).

Avoiding fossil-based carbon in industrial production

CO₂ is already used for various applications in industry. However, it generally only remains bound in this respect for a short period of time, which is not particularly beneficial to the climate. Utilising CO₂ can only be climate-neutral if fossil-based carbon is avoided or if the CO₂ stays permanently bound, for example in concrete. Utilising CO₂ has a further benefit however: CO₂ can replace fossil-based carbon carriers such as crude oil and natural gas in the chemical industry. Furthermore, this can close the carbon cycle in line with the circular economy concept.

The solution: closing the carbon cycle and using climate-neutral fuels

The solution: the carbon must remain within the closed loop of the carbon economy and not be allowed to leave it. This is the only way to prevent the amount of CO₂ in the atmosphere from rising. This works for chemical products like medicines and plastics, for instance. Moreover, to achieve climate neutrality, it is essential that CO₂ is replaced by or transformed into climate-neutral fuels and reactants such as hydrogen or renewable energy. The industrial sector is already transforming the use of CO₂ in its initial projects (see the examples of best practice).

Storage as an alternative to continued use

In contrast to reusing CO₂ (Carbon Capture and Utilisation (CCU)), in the case of Carbon Capture and Storage (CCS), carbon leaves the cycle and is stored over the long-term. Several projects have been created at an international level. Their goal is to provide the service of long-term geological carbon storage.

CO₂ from agriculture and air travel can also be stored

It is possible to prevent CO₂ emissions originating from unavoidable carbon sources from entering the atmosphere by means of storage. Diffuse CO₂ emissions from agriculture and air travel can either be captured in bioenergy applications (Bioenergy Carbon Capture and Storage (BECCS)) or taken directly from the ambient air (Direct Air Carbon Capture and Storage DACCS) and can thus be mitigated.

Carbon sinks in the North Sea are particularly practical for NRW

The largest potential for storing NRW’s CO₂ emissions is reckoned to be in the North Sea, under the upper geological layers of the seabed. CO₂ can be stored there over the long-term in deep-set saline rock layers, in sandstone or in the depleted reservoirs left over from crude oil and natural gas. Initially, only disused natural gas fields at a depth of more than 2.5 kilometres below the seabed could potentially be used as storage facilities for CO₂. These storage facilities are particularly interesting since the North Sea is so close for Germany and especially for NRW. There are also potential areas for storing CO₂ off the coasts of the Netherlands, Norway and the UK. Capacity is currently estimated at 61 to 73 gigatonnes of CO₂.