Decarbonisation Technology February 2026 Issue

CCS: how chemical tracers safeguard future of CO 2 storage How do we prove that captured carbon truly remains underground? Chemical tracer technologies can deliver data-driven certainty

Heinz Weidmann Tracerco

A cross the industrial landscape, carbon capture and storage (CCS) has shifted from demonstration pilot projects to proven pathways. Over the past five years, an accelerating alignment of regulation, incentives, and technology has enabled real progress in capturing and permanently storing carbon dioxide (CO₂). The question is no longer if CCS works, but how well companies can prove it does. The one question that continues to shape technical progress and public perception alike is: How do we prove that captured carbon truly remains underground? Chemical tracer technologies, long used to understand fluid behaviour in the subsurface, are now providing that proof. The same principles that once helped optimise enhanced oil recovery are now being applied to confirm the fate of stored CO₂. These technologies deliver the data-driven certainty that carbon storage integrity depends on to satisfy regulators, reassure communities, and sustain confidence in the permanence of storage. Measurement, monitoring, and verification challenge CCS success depends on more than secure geology. It relies on transparent measurement, monitoring, and verification (MMV) systems that can demonstrate containment beyond doubt (see Figure 1 ). Frameworks such as the US 45Q tax credit rules, Environmental Protection Agency (EPA) Class VI well standards, and emerging international MRV guidelines all require operators to quantify what happens after injection.

Historically, the task of proving CO₂ containment has relied on interpretive methods such as seismic imaging, geochemical analysis, and pressure or temperature monitoring. Each provides valuable information, yet none delivers direct proof. These techniques infer changes in subsurface behaviour rather than physically confirming where injected gas travels or whether it remains trapped. Tracerco’s chemical tracer technology provides the missing link between interpretation and verification. When a minute quantity of an identifiable compound is co-injected with CO₂, it disperses through the formation. It can later be detected in sampling wells, groundwater, through the surface, or produced gas, at sensitivities down to parts-per-trillion. If a tracer signal is found where it should not be, it conclusively indicates CO₂ migration. If no tracer is detected beyond the intended boundary, it confirms containment. Unlike mechanical sensors or seismic surveys, tracers do not interrupt operations. They integrate seamlessly into the injection process and continue to provide data over the life of a storage project. The resulting evidence is quantitative, time-resolved, and directly traceable to specific injection events. These characteristics that make tracers an increasingly valuable component of regulatory-grade monitoring strategies. Inside the science: how chemical tracers work Once injected, chemical tracers travel with the CO 2 into the reservoir, following the same pathways through rock pores, fractures, and capillary networks. Each tracer is a