CO2udslip

CO2udslip is a term used in discussions of carbon capture and storage (CCS) and related carbon accounting to describe unaccounted CO2 that fails to reach its intended permanent fate after capture. In this context, CO2udslip quantifies the difference between CO2 that is captured and the CO2 that is eventually stored or utilized, with losses or leaks treated as slipping away from the planned end state. The term is not yet standardized, and different researchers may define the boundary conditions differently.

The concept rests on boundary definitions. CO2udslip depends on which stages are included in the system boundary, such as capture facilities, transport pipelines, compression, injections, and storage or utilization sites. It is commonly discussed as a complement to capture efficiency, providing insight into the net effectiveness of CCS chains beyond the nominal capture rate.

Common sources of CO2udslip include leaks or venting during gas handling, compression, and transport; storage integrity issues that permit CO2 escape from reservoirs; measurement gaps or reporting inaccuracies; and operational emissions from ancillary processes. Slips can also arise from end-use processes that release CO2 before permanent sequestration.

Measurement and reporting typically rely on mass balance approaches, complemented by leak detection, tracer methods, and periodic integrity assessments. CO2udslip is often expressed as a mass flow rate (e.g., kilograms per hour) or as a percentage of captured CO2. Transparent boundary definitions and uncertainty analysis are essential for reliable use in life cycle assessments and policy evaluations.

See also: carbon capture and storage, fugitive emissions, carbon accounting, slip losses.