CO 2 Storage Monitoring and Verification

The overriding reason for engaging in CCS is to reduce the amount of CO2 escaping into the atmosphere. It is important therefore that a system that clearly defines and determines how this goal can be monitored and verified not only for health and safety purposes or environmental integrity of the project but for resolving issues of liability and help enhancing the risk management strategy.

The operation of CO2 storage require the Measuring, Monitoring and Verification (MMV) of the quantity of CO2 injected and retained in the storage reservoirs for site

395 Hendricks et al 2004, “Global Carbon Dioxide Storage Potential and Costs, ECOFYS report EEP-02001,2004

396 IEA 2008, “CO2 Capture and Storage: A key carbon abatement option”. OECD/IEA 2008

397Id. IEA 2008

398Supra note [Anastassia M., et al. 2009].

399Supra note [IEA 2008].

145 characterisation of the potential geological formation,⁴⁰⁰ to ensure that the CO2 is retained in the formation and that any form of leakage is at the minimum.⁴⁰¹ With these as necessary indicators, Anderson (2003) further suggested that the procedure should ensure the monitoring of any subsurface movement and environmental [and ecological] impacts.⁴⁰²

In relation to environmental impact, the main concern would be the resulting liability from public health and safety hazards due to the escape of CO2 into the atmosphere and the potential contamination of groundwater aquifers. It is however possible as a risk mitigation strategy to monitor the groundwater contaminant flow by seismic technologies akin to that used by Statoil in the Sleipner CO2 storage project.⁴⁰³ Exposure to CO2 at high concentration is one of the main causes of concern for public health and safety in the CCS technology implementation since CO2 at normal concentration does not impact on the environment and ecology due to ease of dissipation in the atmosphere over time. However, with possible blow-outs during injections or transportation of the gas, large volume leaks resulting to high

concentration at low level area could be catastrophic.

There are various monitoring technologies and measuring techniques for determining the exposure of an area to high CO2 concentration (see Table 8). The monitoring of leakage into the Vadose zone (an area directly above the water table) can be measured by observing the soil air concentration of CO2, the flux from the

surrounding soils and the impact on the surface concentration of CO2.⁴⁰⁴ (See figure 26 below). On a commercial scale and due to occupational implications, advance technological sensors are used to help with continuous monitoring of CO2 levels in the air,⁴⁰⁵ while groundwater monitoring can be achieved by the analysis of noble

400 Anderson, J., 2003, “Monitoring and Verification of Geological and Ocean Carbon Dioxide Disposal, Verification Yearbook.

401Id.

402Id

403 McKenna J., et al 2001, “Time-lapse 3-D seismic imaging of shallow subsurface contaminant flow”, Journal of Contaminant Hydrology, Vol. 53, Issues 1–2, 1 December 2001, Pages 133–150 Published by Elsevier

404Yingqi Zhang et al (2004), Vadose Zone Remediation of CO₂ Leakage from Geologic CO₂ Storage Sites (LBNL-54680); Carbon Sequestration Leadership Forum Discussion Paper from the Task Force for Identifying Gaps in CO₂ Monitoring and Verification of Storage 9 (CSLF-T-2005-10, 2005);

405 IPCC Special Report (2005) pg. 239

146 gas and Isotope.⁴⁰⁶ Lewicki (2005) indicated that overcoming the difficulty

associated with differentiating between natural ecological flux and the leakage of CO2 in small quantities from storage reservoir can be achieved by developing methods that aim at proficiently collecting data properties associated with CO2

leakage at the same time reduce the natural CO2 flux.⁴⁰⁷ It is therefore of necessity in my opinion that to eliminate such concerns such methodology is integrated in the relevant national regulatory framework.

Table 8 Monitoring and Verification Techniques for CO2 Storage (adapt from IPCC Special Report)

Monitoring Techniques Application

Introduction and Natural tracers Flux of CO2 can be traced in geological storage reservoirs

Solubility trapping can be measured Tracing of leakage

Vertical seismic profiling and cross-well seismic imaging

Detecting detailed distribution of CO2 in the storage formation

Detecting leakage through faults and fractures

Time-lapse 3-D seismic imaging Tracking CO2 movement and above storage formation

Passive seismic monitoring Development of micro-fractures in formation and caprock

CO2 migration pathway Electrical and electromagnetic

techniques

Tracking movement of CO2 in and above the geological reservoir

Subsurface pressure Control of formation pressure below fracture gradient

Wellbore and injection tubing condition Leakage out of the storage formation

Well logs Tracing CO2 movement in and above

storage formation

Tracking migration of brine into shallow aquifers

Calibrating seismic velocities for 3D seismic surveys

Water composition Quantifying solubility and mineral trapping

Quantifying CO2 –water-rock interactions

Detecting leakage into shallow groundwater aquifers

Soil gas sampling Detect elevated levels of CO2

Identify source of elevated soil gas CO2

406Supra note [Carbon Sequestration Leadership Forum Discussion Paper]

407Lewicki J. L., 2005, “An Improved Strategy to Detect CO2 Leakage for Verification of Geological Carbon Sequestration, 32 GEOPHYS. RES. LETT. L19403.

147 Evaluation ecosystem impacts

CO2 land-surface flux monitoring by flux chamber or eddy-coveriance

Detect, locate and quantify CO2 release Visible and infrared imaging from

satellite or planes

Detect vegetative stress

Finally, another monitoring concern is with regards the economic impact vis-à-vis compromising the integrity of such incentive based program. Small leaks over a long period of time may not necessarily impact the public health but could compromise the economic integrity⁴⁰⁸ of the project due to the incentive based nature of the CDM project. This problem would arise in a case when on the long term the initial carbon emissions reduction (CER) credits or allowances or offsets have been received by the different parties involved but eroded by continuous but gradual release of CO2

into the atmosphere even when the implementation phase and contractual liability is ended or over a long period when the receipt of the incentive no longer exist. In this

408 Marston P.M et al (2008), “From EOR to CCS: The Evolving Legal and Regulatory Framework For Carbon Capture And Storage”, Energy Law Journal [Vol. 29:421-490 2008]

Figure 26 Scientists collect a sample of naturally-occurring gases that are found in the soil at the Otway Project site prior to the injection of CO2. Regular sampling of the soil gas is part of the monitoring program. Source: CO2CRC website CRC for Greenhouse Gas Technologies

148 case, it is important a set out financial security for ongoing monitoring and

verification through either by government or privately funded mechanism in place to mitigate any associated risks or financial losses.

149 Chapter 4