Methodology to deploy shallow-focused subsea CCS technologies

Synthesis Report on network designs for CCS site marine Measurement, Monitoring and Verification

This provides an overarching Executive Summary to the whole project consisting of 7 separate research studies.

Part 1: Optimising sensor configurations on fixed and mobile platforms for improved signal retrieval

Key outcomes from the experimental investigation of optimal sensor configurations include:

• The validation, in-field, of sensors integrated on several platforms;
• Conclusion of initial testing of the sensor configurations on the Unmanned Surface Vehicle (USV), moorings and landers;
• The development of operational configurations and procedures for the USV;
• Limited demonstration of near-real time (NRT) data stream processing for data from the sensors due to issues with acoustic performance (with alterations to be implemented prior to the May 2019 field deployment of equipment); and
• The development of initial recommendations for optimisation of the MM&V network design.

Part 2: Near Real Time and Delayed Mode data QC protocols

The report documents the near-real-time (NRT) and delayed mode (DM) data quality control protocols, metadata structures and archive file formats for data generated by the fixed and mobile platforms deployed into the near shore area during 2018.

Part 3: Modelling

The work addresses CO₂ plume signal analysis and optimised sensor network configuration within a 3D hydrodynamic model of Bass Strait. Two numerical ocean models were deployed for offshore Gippsland. The models provide unique insight into the morphology of a hypothetical CO₂ release and how it differs from the naturally varying background and allow the detection and impact length scales of any artificial release to be estimated providing critical information for monitoring design.

Part 4: Biological Investigation

The study focuses on investigation of natural variability in biological indicators of environmental impact. The approach taken has been to first gather biological data on the Gippsland area via a number of targeted field surveys. This data has enabled an understanding of the patterns of diversity and abundance of subtidal benthic sediment infauna, meiofauna and flora present in the area. This data was then considered in the context of international literature on biological impacts of CO₂ to assess whether any biota present in the Gippsland region may prove to be useful parameters for CCS monitoring purposes.

Part 5: Fixed Platforms

The report highlights application of fixed sensor network designs for CCS site marine measurement, monitoring and verification. The work demonstrates instrumental and operational constraints of fixed MM&V platform deployment into the coastal Gippsland marine environment are now well understood. The surface moorings and seabed landers tested during this project have been proven to be capable of sustained observations of the order of 6 to 9 months without intervention. The on-board sensor systems provided high quality datasets which have enabled characterisation of the oceanographically complex, high energy coastal Gippsland environment. The in-water measurements taken during the deployments have also begun to characterise the tidal, diurnal and seasonal variation at the Gippsland study site. These data have been critical calibration data for the 3D biogeochemical models developed for the project.

Part 6: Mobile Platforms

The work reports on considerations for integration of mobile platforms with a fixed sensor design network. It investigates how the spatio-temporal variance structure of a marine CCS site may be characterised and monitored using mobile monitoring platforms.  Within the marine technology domain, it is widely acknowledged that autonomy will underpin the future of ocean operations. Unmanned surface and autonomous underwater vehicles (USVs and AUVs) are rapidly evolving in their performance, sophistication, and accessibility. The work demonstrates that mobile platforms are an essential part of a MM&V program where both crewed vessels and unmanned surface vessels play a valuable and differentiated MM&V role.

Part 7: Feasibility and design study of a cabled marine monitoring and verification system

This work delivers a design study for integrating the sensor technologies into a cabled observatory concept. It was designed to provide a CCS proponent with several options that will permit robust and cost-effective Marine M&V plans to be developed. It reports on engineering constraints, data processing requirements and a suite of sensors and platforms that might be employed during the planning process.

Several cabled observatory configuration scenarios, from sparsely to highly instrumented, were developed and discussed to compare and contrast different deployment configurations and replications of the core 3 – platform system. In addition, three potential construction and maintenance vessel options were examined and a cost model developed.

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