Otway Project: atmospheric monitoring
The CO2CRC Otway Project Atmospheric Monitoring Program aims to verify that injected CO2 stays underground and demonstrate the capacity to detect and quantify surface leakage in the unlikely event of leakage to the surface.
The program will develop, test and deploy new and enhanced monitoring and verification (M&V) technologies that might apply to commercial-scale carbon capture and storage projects in the future.
The program is conducted by CO2CRC and CSIRO Marine and Atmospheric Research. It is one of the most comprehensive and one of the few continuous atmospheric programs dedicated to monitoring CO2 stored underground in the world.
CanSyd Australia has worked with CO2CRC to design, build and demonstrate CO2 atmospheric and soil flux monitoring instruments at the CO2CRC Otway Project that would give early warning in the unlikely event of CO2 leakage from the geological storage site.
The natural biological flux (emission and uptake) of CO2 is large and variable compared to the emissions from a hypothetical leak. Local agricultural and industrial emissions can also be significant. Understanding these natural variations plays an integral part in successfully monitoring for leakage.
The CO2 concentration measured at Otway before CO2 injection (Figure 1) shows these fluxes cause large variations compared to the CO2 concentration at Cape Grim, Tasmania, during “baseline” conditions (strong south westerly winds off the ocean).
The CO2CRC Otway Project Atmospheric Monitoring Program incorporates ongoing monitoring for many years.
- an atmospheric station with a CSIRO LoFlo CO2 analyser continuously measuring concentrations of CO2;
- a CO2 flux tower continuously measuring surface-air CO2 fluxes of a representative area of the site;
- soil CO2 flux measurements taken at many point locations across the region;
- modelling of the ecosystem CO2 and pre-existing industrial/agricultural CO2 sources;
- measuring tracers to help confirm the origin of the CO2 emissions to the local atmosphere and to quantify emissions; and,
- headspace gas sampling to establish the presence, concentration and distribution of any CO2 or related gases, and their distribution within three nominated water boreholes adjacent the project.
- The atmospheric monitoring installed at the Otway Project site has many benefits: it is continuous, unattended, flexible, relatively economical, and not invasive
- The atmospheric monitoring has been important in gaining the acceptance of regulatory bodies and the public
- It has quantified background gas concentrations and fluxes for a year before injection
- Monitoring CO2 isotopes has shown their potential use as naturally occurring tracers for this project
- If all components of the enhanced strategy are in place, the potential exists to independently detect and quantify relatively small leaks
- Atmospheric monitoring can potentially provide independent assurance verification to complement other assurance monitoring technologies