Integrated Annual Report 2025

What is a carbon capture and sequestration (CCS) chain?

Guillaume Rodrigues : A CCS chain involves four stages: on-site capture; CO₂ specification adjustment (purification) at the industrial facility; transport-either in gaseous or liquid phase; and, finally, sequestration in suitable geological formations. Depending on the project, our scope of intervention ranges from a standalone capture unit to a solution that includes liquefaction. Air Liquide works with partners for injection and sequestration.

What criteria determine whether a capture project is competitive?

There are two key parameters. First, carbon concentration: the higher it is, the more efficient the capture. For example, CO₂ concentration in cement plant flue gases reaches 15% to 30%, whereas it is below 5% in a gas-fired power plant. Therefore, capture in the latter case is far less economic. Second, energy: its availability, carbon footprint and cost are critical.

To ensure both the economic and environmental viability of a project, we prioritize the use of low-carbon electricity or the recovery of heat produced by the industrial site. The objective is to capture up to 98% of the CO₂ emitted at the boundaries of the capture unit.

How do you design capture solutions that can adapt to different industrial sites?

There is no single technology that meets every need, so we take an approach tailored to each emission source. We always begin by analyzing the CO₂ concentration in the gas to be treated in order to select the appropriate technological building block from our Cryocap™ range. Our FG(1) version is suited to industrial flue gases (15% to 50% CO₂), while OXY is for very carbon-rich gases (above 50%). And Cryocap H₂ is suited to gases resulting from hydrogen production processes. We then size each unit on a case-by-case basis to capture up to 98% of the CO₂ physically present in the gas stream.

Actual performance, however, is measured in terms of CO₂ avoided, taking into account the carbon footprint of the energy consumed. Finally, we must adapt to the impurities present in each source. Our R&D and Engineering teams identify these specific compounds to treat them in a tailored and competitive manner.