How does the carbon capture chain work?

Post-combustion capture is the most widely applicable method. Flue gas from an industrial process or power station is passed through a chemical solvent (typically an amine solution) that selectively absorbs CO2. The CO2-rich solvent is then heated in a regeneration column to release the CO2, which is compressed to a supercritical state (above 73 bar) for pipeline transport. The regenerated solvent is recycled. The energy penalty for this process is significant, typically 15-25 per cent of the plant's output, which is why capture costs dominate the total CCUS chain cost.

Geological storage relies on multiple trapping mechanisms. Structural trapping keeps CO2 beneath an impermeable cap rock. Residual trapping immobilises CO2 in pore spaces. Dissolution trapping dissolves CO2 into formation water. Mineral trapping converts CO2 into solid carbonate minerals over thousands of years. Natural analogues (underground CO2 reservoirs that have retained gas for millions of years) and decades of experience from enhanced oil recovery operations provide strong evidence that well-chosen storage sites can retain CO2 indefinitely. The regulatory framework requires monitoring during and after injection, with liability transferring to the government after a defined period under the Energy Act 2023.

The Transport and Storage Regulatory Investment (TRI) model creates a regulated asset base for CO2 pipeline and storage infrastructure, similar to how gas and electricity networks are regulated. T&S operators earn a regulated return on their capital investment, with the revenue recovered from emitters who pay a per-tonne transport and storage fee. This model reduces investment risk by guaranteeing a return, making it attractive to institutional investors. The licence is granted by the NSTA (North Sea Transition Authority), and Ofgem oversees the economic regulation. The key design challenge is setting initial capacity and pricing when demand from capture projects is still uncertain.

The 2024 programme differs from previous attempts in three key ways. First, it commits 21.7 billion pounds rather than running a small competition, providing scale. Second, it uses the cluster model with shared transport and storage infrastructure, creating economies of scale rather than funding isolated demonstration projects. Third, it separates the T&S infrastructure (regulated utility model) from capture projects (contract-based support), which allows different risk profiles to be managed appropriately. The question is whether this design is sufficient to overcome the credibility deficit created by previous cancellations.