CO2 capture, a lever for decarbonisation

CO2 capture, a lever for decarbonisation

CO2 is a greenhouse gas whose role in climate change is well established. Since the beginning of the industrial era, its concentration in the atmosphere has risen steadily, linked to the intensification of human activity, particularly industrial activity. Today, targets have been set to reduce greenhouse gas emissions at French, European and international levels. To support these objectives, CO2 capture, storage and recovery solutions are particularly promising.

What is CO2 capture?

The aim is to recover CO2 at its source of production, in industrial emissions. Three capture technologies are currently being studied:

  • "post-combustion" capture, the most widely used technique, consists of recovering the CO2 by washing the fumes emitted by combustion with a solvent;

  • pre-combustion capture involves transforming the fuel into a synthesis gas made up of water, hydrogen and carbon monoxide. This is converted into CO2 by introducing water vapour into the synthesis gas. The CO2 and hydrogen are then separated by a solvent, enabling them to be captured;

  • oxy-combustion capture requires the fuels to be burnt in the presence of pure oxygen instead of air, which results in fumes with a higher concentration of CO2 and therefore makes it easier to separate the CO2 from the water vapour.

However, there is no point in capturing the molecule if it cannot be transported, stored and/or used. It is therefore also important to develop suitable transport and storage infrastructures. This is part of a CCUS (Carbon Capture, Utilisation and Storage) process.

Why capture CO2?

France and Europe have set themselves the goal of achieving carbon neutrality by 2050, which means decarbonising industry. The introduction of CO2 capture, transport and storage solutions, alone or in conjunction with other systems, would appear to be one way of achieving this decarbonisation.

All the more so as, for certain heavy industries (steelworks, iron and steel or cement works for example), the use of renewable energies and the principles of energy sobriety, although essential, will not be sufficient to massively reduce their greenhouse gas emissions. CCUS technologies are therefore particularly interesting for these industries, which are difficult to decarbonise.

CO2 capture: what next?

Once the CO2 has been extracted from the industrial flue gases, it must be transported:

  • Either by pipelines

  • Or by boat

  • Or by train or lorry

The captured CO2 is then transported to be stored underground or recycled.
Different types of structures are used for storage:

  • deep saline aquifers, reservoirs of unclean salt water located at great depths;

  • depleted hydrocarbon deposits.

The former offer significant storage potential, but they need to be studied further to gain a better understanding of their structure and their capacity to trap CO2 over the long term. The latter have already demonstrated their ability to store hydrocarbons for several million years. Today, we need to ensure that operating them has not compromised their airtightness.

Captured CO2 can also be considered as a resource to be exploited. For example, in combination with renewable hydrogen, it can be used to produce synthetic methane, thereby contributing to the development of multi-energy networks.

The CCUS sector: what's at stake?

The potential of CCUS is very real. The main challenge today is therefore to set up a truly dedicated industry, involving large-scale capture facilities as well as the massive development of transport networks, storage sites and industrial processes capable of recovering CO2.

A number of projects have been launched, such as the regional PYCASSO project supported by Teréga. In the same vein, Teréga has launched a Call for Expressions of Interest (AMI) from 26 June to 13 October 2023, dedicated to the transport and storage of hydrogen (H2) and/or carbon dioxide (CO2).

What is the aim? Obtain a clearer view of the needs of the various regional, national and European players in this field and enable Teréga to develop the architecture of its projects to best meet their expectations.