Why is this research needed?

Understanding detectability limits when monitoring for leakage is particularly important for project operators, and for providing assurance and evidence to regulators, local populations, investors/insurers and policy makers. This project undertakes an impartial review to understand CO2 detectability thresholds in the environment, and to link leakage rates to detectable limits, through application of new techniques and methods, and to equip storage project stakeholders with techniques, methods and evidence to constrain future post-closure liability and reduce costs.

In the unlikely event that geological CO2 storage sites were to leak, surface expression will vary widely, both temporally and spatially. Mobile techniques that can quickly and reliably screen large areas for further focused investigation are therefore needed. However, sensitivity is often sacrificed for mobility, reducing the chances of successful detection of low CO2 concentrations.

This project will undertake an impartial and systematic review to benchmark the efficacy of established and newly developed sensors and techniques with fixed and mobile deployments and attempt to quantify the extent to which CO2 leakage is under- or over-estimated. Benchmarking will consider field sensitivity, accuracy, feasibility and applicability for deployment at full-scale. Leakage of a known quantity of CO2 will be used to establish realistic detection limits. Commercially available and researcher-developed sensors will be assessed. Numerical modelling will be used to predict the amount of CO2 leakage and this will be compared to the known value.

These results will help define a tiered response with wide-area techniques for large-area screening, and more focused follow-up techniques for specific areas of interest. This project will assess how findings at this field scale can be upscaled to monitor full-scale onshore CO2 transport and storage infrastructure through engagement with storage project developers.

What is this research investigating?

The objectives of this proposal are to understand leakage detection limits of a range of mobile and fixed techniques in order to support project developers in providing assurance on security and engagement with local stakeholders:

1) Understand CO2 detectability thresholds in the environment, and link leakage rates to detectable limits
2) Benchmark the efficacy of established and newly developed near-surface gas sensors and techniques with fixed and mobile deployments and attempt to quantify the extent to which CO2 leakage is under- or over-estimated by these techniques
3) Upscale research findings to understand relevance of opportunities, issues and risks to commercial scale CO2 transport and storage

This project will also build capacity in the UK ECCSEL BGS near-surface gas sensing facility.

What does the research hope to achieve?

The research will be of benefit to those seeking to use CO2 sensors to detect and quantify CO2 at surface, providing assurance on the detection thresholds and ease of field deployment of various sensors. This will include commercial and cost-efficient options to suit a range of budgets. The aim is to benchmark the sensitivity and deployability of monitoring sensors and techniques for CO2 detection and quantification, including at kilometre-scale. The output report will offer an impartial review of the application of various sensors and techniques considering sensitivity and deployability.

Understanding detection limits when monitoring for leakage is particularly important for project operators, and for providing assurance and evidence to regulators, local populations, investors/insurers and policy makers.

Results will be disseminated to a wide academic audience through participation at the UKCCSRC conference and webinar, and the CO2GeoNet Open Forum, where it will also gain the attention of relevant industrial stakeholders.