CCS (CCS)

Carbon Capture and Storage (CCS) is a suite of technologies that capture carbon dioxide produced by combustion or industrial processes, transport it to a storage site, and inject it deep underground for permanent geological sequestration. The intent is to prevent CO₂ from reaching the atmosphere, thereby contributing to greenhouse-gas reduction targets without requiring an immediate switch away from carbon-emitting fuels or processes.

CCS has three components. Capture separates CO₂ from a mixed gas stream using amine scrubbing (post-combustion), oxy-fuel combustion, or pre-combustion gasification. Transport moves the captured CO₂ — typically by pipeline at over 100 bar in dense-phase, occasionally by truck or rail — to the injection site. Storage injects CO₂ into deep saline aquifers, depleted oil and gas reservoirs, or unmineable coal seams at depths over 800 m, where reservoir pressure keeps CO₂ in supercritical phase and trapping mechanisms (structural, residual, solubility, and mineral trapping) hold it for thousands of years.

In a biogas or CBG context, CCS intersects with upgrading: biogas upgrading already separates a high-purity CO₂ stream as a by-product. Capturing and sequestering this biogenic CO₂ converts a carbon-neutral process into a carbon-negative one, generating credits under voluntary markets and potentially under India's Carbon Credit Trading Scheme (CCTS) once methodology approvals are finalised. India does not yet have a commercial-scale CCS facility. The National CCUS Mission has identified potential storage sites in the Cambay, Krishna-Godavari, and Mumbai basins, but commercial deployment is held back by high capex (estimated at $50–100 per tonne CO₂ for the full chain), the absence of a CO₂ pipeline grid, and unsettled long-term liability rules for stored CO₂. For CBG plants, the more accessible near-term opportunity is selling food-grade CO₂ to beverage and dry-ice markets — a route currently blocked only by purification capex.