CCS Comparison Matrix

 

SUMMARIES

COMPARISONS: SIMILARATIES & DIFFERENCES

Key Issue

WRI CCS Guidelines

U.S. EPA

EU Geologic CO2 Storage Directive

WRI CCS Guidelines vs. U.S. EPA

WRI CCS vs. EU

U.S. EPA vs. EU

Siting requirements that focus on geologic characteristics

Specific guidelines are given for site characterization and selection, including a set of guidelines for (1) determining the functionality of confining zone(s), (2) determining injectivity, and (3) determining capacity (Storage Guideline 5).

 

The geologic system must be comprised of (1) an injection zone of sufficient areal extent, thickness, porosity, and permeability to receive total anticipated volume of CO2, and (2) a confining zone(s) that is free of transmissive faults or fractures and sufficient areal extent and integrity to contain injected CO2 stream and displaced formation fluids and allow injection at proposed maximum pressures and volumes without initiating or propagating fractures in the confining zone(s) (§146.83).

The site characterization permit (issued prior to the storage permit) includes a four-step process for site selection. The data collection requirement (Step 1) includes collection of site-specific data including reservoir engineering (including volumetric calculations of pore volume for CO2 injection and ultimate storage capacity, pressure and temperature conditions, pressure volume behavior as a function of formation injectivity, cumulative injection rate and time), and identifying the presence and condition of natural and man-made pathways including wells and boreholes which could provide leakage pathways (Annex 1, Step 1: Data Collection).

 

Similarity. Both the WRI Guidelines and U.S. EPA proposed rule require the presence of a cap rock that is laterally extensive, relatively thick, and without penetrations or faults that are predicted to serve as conduits for CO2 outside the injection reservoir, as well as the presence of an injection formation that can store the anticipated volume of CO2.  

 

Similarity. Both the WRI Guidelines and the EU Directive require the collection of site-specific data to determine injectivity (projected pressure and volume behavior) and storage capacity, and to prove the functionality of the confining zone by identifying potential leakage pathways.

 

Similarity. Both the U.S. EPA proposed rule and the EU Directive include provisions that require providing information to show that a proposed storage site has the needed capacity and the presence of a confining zone which will ensure the integrity of the storage.

Flexibility in choice of monitoring tools

Operators should have flexibility to choose specific monitoring techniques and protocols that will be deployed at each storage site, as long as methods selected provide data at resolutions that will meet stated monitoring requirements (Storage Guideline 1b).

 

The testing and monitoring plan must be submitted with the permit application for Director approval, and must include a description of how the owner or operator will meet the requirements of this section

(§146.88).

Note: The U.S. EPA rule does require minimum monitoring and gives some specificity with respect to corrosion monitoring in the well.

Choice of monitoring technology shall be based on best practice available at the time of design. The Directive provides three technology selection options that shall be considered and used as appropriate (Annex II).

 

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule preserve flexibility for operators to develop a site-specific monitoring plan based on the unique local geologic conditions and informed by site-specific data collected during characterization.

 

 

Similarity. Both the WRI Guidelines and the EU Directive preserve the flexibility for operators to develop a site-specific monitoring plan based on the unique local geologic conditions and informed by site-specific data collected during characterization.

 

Similarity. Both the U.S. EPA proposed rule and the EU Directive preserve the flexibility for operators to develop a site-specific monitoring plan based on the unique local geologic conditions and informed by site-specific data collected during characterization. Both also offer suggestions to guide monitoring tool selection.

 

Flexible monitoring area

The monitoring area should be based initially on knowledge of the regional and site geology, overall site-specific risk assessment, and subsurface flow simulations. This area should be modified as data obtained during operations warrants (Storage Guideline 1d).

The area of review is based on computational modeling that accounts for physical and chemical properties of all phases of the CO2 stream. Periodic reevaluation of delineation is required (§146.84).

Member States shall ensure that the operator carries out monitoring of the injection facilities, the storage complex (including where possible the CO2 plume), and where appropriate the surrounding environment (Article 13).

 

One component of establishing a monitoring plan is inclusion of…. (c) monitoring locations and spatial sampling rationale and (d) frequency of application and temporal sampling rationale (Annex II).

 

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule acknowledge that the monitoring area should reflect the site-specific geological conditions and be determined based on modeling that employs site-specific data. This area may change throughout the course of a CCS project and may need to be periodically reevaluated. 

Similarity. Both the WRI Guidelines and the proposed EU Directive acknowledge that the monitoring area should reflect the site-specific geological conditions and be developed for each site and be determined based on modeling that employs site-specific data. This area may change throughout the course of a CCS project and may need to be periodically reevaluated.

 

 

Both the U.S. EPA proposed rule and the EU Directive acknowledge that the monitoring area should reflect the site-specific geological conditions and be developed for each site and be determined based on modeling that employs site-specific data. This area may change throughout the course of a CCS project and may need to be periodically re-evaluated. Both the proposed EPA rule and the EU Directive include provisions for updating the monitoring plan.

Monitoring and data collection

MMV requirements should not prescribe methods or tools. Rather, they should focus on key information an operator is required to collect for each injection well and overall project, including: injected volume; flow rate or injection pressure; composition of injectate; spatial distribution of CO2 plume; reservoir pressure; well integrity; determination of any measurable leakage; and appropriate data (including formation fluid chemistry) from monitoring zone, confining zone, and underground sources of drinking water (Storage Guideline 1a).

Reporting requirements outlined in §146.91 include reporting the characteristics of the CO2 stream, injection pressure, flow rate, volume and annular pressure (monthly averages), and volume of CO2 injected, as well as other criteria (§146.91).

 

Parameters to be monitored are identified so as to fulfill the purposes of monitoring. However, the plan shall in any case include continuous or intermittent monitoring of the following: fugitive emissions of CO2 at injection facility; CO2 volumetric flow at injection wellheads; CO2 pressure and temperature at injection wellheads (to determine mass flow); chemical analysis of injected material; reservoir temperature and pressure (to determine CO2 phase behavior and state) (Annex III).

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule identify data requirements for operational monitoring that are largely consistent. Both frameworks recommend that an operator report the composition of the injected fluid, the volume injected, the flow rate, and reservoir pressure.

 

Similarity. Both the WRI Guidelines and the EU Directive identify data requirements for operational monitoring that are largely consistent. Both frameworks recommend that an operator report the composition of the injected fluid, the volume injected, the flow rate, and reservoir pressure, and reporting of any fugitive emissions.

Similarity. Both the U.S. EPA and the EU Directive identify data requirements for operational monitoring that are largely consistent. Both frameworks recommend that an operator report the composition of the injected fluid, the volume injected, the flow rate, and reservoir pressure.

 

Difference. The U.S. EPA proposed rule does not specify reporting leakage emissions as an operational data requirement.

Model update requirements

The reservoir and risk models should be recalibrated (or history-matched) periodically based on operational data and re-run flow simulations; immediate updates should be made if significant differences in expected and discovered geology are found (Storage Guideline 6f).

Operational data should be collected and analyzed throughout a project’s operation and integrated into reservoir models and simulations. Data collected should be used to history-match (calibrate) the project performance to the simulation predictions (Storage Guideline 6m).

 

Predict, using computational modeling, the projected lateral and vertical migration of the CO2 plume and formation fluids in subsurface from commencement of injection activities until plume movement ceases, pressure differentials sufficient to cause movement of injected fluids or formation fluids into an Underground Source of Drinking Water (USDW) are no longer present, or after a fixed time period as determined by the Director. The model must be based on detailed geologic data collected to characterize the injection zone, confining zone and any additional zones; and anticipated operating data. It must also take into account any geologic heterogeneities, data quality, and their possible impact on model predictions (§146.84).

The data collected from monitoring shall be collated and interpreted. The observed results shall be compared with behaviour predicted in dynamic simulation of 3-D-pressure-volume and saturation behaviour undertaken in the context of the security characterization. Where there is a significant deviation between observed and predicted behaviour, the 3-D-model shall be recalibrated to reflect the observed behaviour. Recalibration shall be based on the data observations from the monitoring plan, and where necessary to provide confidence in the recalibration assumptions, additional data shall be obtained. Where new CO2 sources, pathways, and flux rates or observed significant deviations from previous assessments are identified as a result of history matching and model recalibration, the monitoring plan shall be updated accordingly (Annex II, section 1.2).

 

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule include provisions for using a model that is based on site-specific, operational data and that this model should be updated. The detailed provisions for model updates differ slightly with the U.S. EPA rule allowing for updates after a fixed time.

Similarity. Both the WRI Guidelines and the EU Directive include provisions for operational monitoring data being compared with (history-matching) predictive models, with models updated where there are significant differences between observed and predicted values.

Similarity. Both the U.S. EPA proposed rule and the EU Directive include provisions for using a predictive model that is based on operational data, which is updated throughout a project. The detailed provisions for model updates differ slightly with the U.S. EPA rule allowing for updates after a fixed time.

Risk analysis and contingency plans

A risk assessment should be required along with development and implementation of a risk management and risk communication plan for all storage projects. Risk assessments should, at a minimum, examine potential for leakage of injected or displaced fluids via wells, faults, fractures and seismic events, and the fluid’s potential impacts to integrity of the confining zone and endangerment to human health and the environment (Storage Guideline 2a).

§146.84 outlines the criteria for the area of review and corrective action. In this section it states that the model must “consider potential migration through faults, fractures, and artificial penetrations.” An emergency and remedial response plan is also required, as outlined in §146.94.

Security, sensitivity, and hazard characterization are outlined as requirements. Specifically, the risk assessment should include hazard characterization, an exposure assessment, an effects assessment, and a risk characterization (Annex 1, Step 4).

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule emphasize the need for identifying potential leakage pathways and evaluating them as well as having plans in place to manage the risks associated with unexpected movement of CO2.

 

Similarity. Both the WRI Guidelines and the EU Directive emphasize the need for identifying potential leakage pathways and evaluating them in the context of a site-specific risk assessment.

Similarity. Both the U.S. EPA proposed rule and the EU Directive emphasize the need for identifying potential leakage pathways based on site-specific information.

Inclusion of area of elevated pressure

Storage project footprint is defined as the area above the "injected or displaced fluids". This area is the focus of many Guidelines, including those for Monitoring, Risk Analysis, and Post-Closure non-endangerment criteria (Storage Guidelines 1d, 2a, and 7d).

Pressure front is defined as “the zone of elevated pressure that is created by the injection of carbon dioxide into the subsurface. For geologic storage projects, the pressure front of a CO2 plume refers to the zone where there is a pressure differential sufficient to cause the movement of injected fluids or formation fluids into a USDW.” This pressure front is included as part of the geologic storage project definition. Location of this area is included as a monitoring requirement (§146.90 and §146.93).

Pressure volume behavior is included as a requirement for site characterization in the context of modeling and monitoring (Annex I).

Similarity. Both the WRI Guidelines and the U.S. EPA proposed rule include consideration of the area of elevated pressure that is associated with the injected CO2 in provisions for modeling and monitoring.

 

Similarity. Both the WRI Guidelines and the EU Directive include consideration of the area of elevated pressure (or pressure volume behavior) that is associated with the injected CO2 in provisions for modeling and monitoring.

 

Similarity. Both the U.S. EPA proposed rule and the EU Directive include consideration of the area of elevated pressure (or pressure volume behavior) that is associated with the injected CO2 in provisions for modeling and monitoring.

 

Financial responsibility

Based on site-specific risk assessment, project operators / owners should provide an expected value of the estimated costs of site closure (including well plugging and abandonment, MMV, and foreseeable corrective (remedial) action) as part of their permit application. These cost estimates should be reviewed and updated as needed prior to undertaking site closure (Storage Guideline 3a).

 

Project operators / owners should demonstrate financial assurance for all of the activities required for site closure (Storage Guideline 3b).

 

Policies should be developed for adequately funding the post-closure activities that become the responsibility of an entity assuming responsibility for long-term care as described in the Post-Closure Section (Storage Guideline 3c).

 

The entities need to be adequately funded over time to conduct the post-closure activities for which they are responsible (Storage Guideline 8b).

The owner or operator must demonstrate and maintain financial responsibility and resources for corrective action, injection well plugging, post-injection site care and site closure, and emergency and remedial response until the completed post-injection site care and site closure plan are approved and the regulatory authority determines that the site has reached the end of the post-injection site care.

 

The owner or operator must provide written updates of adjustments to the cost estimate to account for any amendments to the area of review and corrective action plan and the post-injection site care and site closure plan, or if there is reason to believe that the original demonstration is no longer adequate to cover the cost of injection well plugging and post-injection site care and site closure.

 

EPA plans to develop guidance that is similar to current UIC financial responsibility guidance for Class II owners or operators (§146.85 Financial Responsibility).

 

 

Member States are required to ensure that the operator, on the basis of modalities to be decided by Member States, makes a financial contribution available to the competent authority before the transfer of responsibility has taken place. The contribution should take into account the criteria referred for characterization and assessment of the storage complex and surrounding area and elements relating to the history of storing CO2 relevant to determining the post-transfer obligations, and cover at least the anticipated cost of monitoring for a period of 30 years. This financial contribution may be used to cover the costs borne by the competent authority after the transfer of responsibility to ensure that the CO2 is completely and permanently contained in geological storages sites after the transfer of responsibility (Article 20: Financial Mechanism).

 

Similarity. Both the WRI Guidelines and the proposed U.S. EPA rule include provisions for demonstrating financial responsibility that include the costs of site closure and that are updated as needed.

 

Difference. The WRI Guidelines include provisions for funding continued monitoring of a site by another entity after the site is certified as closed.

Similarity. Both the WRI Guidelines and the EU Directive require that the operator demonstrate financial responsibility for the expected costs of a storage project.

 

Difference. In the EU Directive the costs of post-closure monitoring are paid by the operator, whereas the WRI Guidelines specify that post-closure monitoring should be adequately funded without specifying the origin of that funding.

Similarity. Both the U.S. EPA proposed rule and the EU Directive require that the operator demonstrate financial responsibility for the expected costs of a storage project.

 

Difference. The EU Directive includes coverage for 30 years of monitoring as part of the plan; under the U.S. EPA rule the default time period would be 50 years, although this is not mentioned explicitly in the financial responsibility section.

 

Register of storage sites

If one does not already exist in a jurisdiction, a publicly accessible registry should be created for well plugging and abandonment data (Storage Guideline f).

 

 

There is no direct mention of requirements for maintaining a register of storage sites. However, there are requirements for reporting post-closure information to the regulator:

 

Under §146.93, post-injection site care and site closure requirements, once the Director has authorized site closure, the owner or operator must submit a site closure report within 90 days that must thereafter be retained at a location designated by the Director. The report must include, among other things, a documentation of appropriate injection and monitoring well plugging as per specifications under plugging report.

 

The owner or operator must retain for three years following site closure records collected during the post-injection site care period. The owner or operator must deliver the records to the Director at the conclusion of the retention period, and the records must thereafter be retained at a location designated by the Director for that purpose (§146.93, Post-injection site care and site closure requirements).

 

The competent authority shall establish and maintain a register of the storage permits granted and a permanent register of all closed storage sites and surrounding storage complexes, including maps and sections of their spatial extent and available information relevant for assessing that the stored CO2 will be completely and permanently contained. The register shall be taken into consideration by the competent national authorities in relevant planning procedures and when permitting any activity that could affect or be affected by the geological storage of CO2 in the registered storage sites (Article 25).

 

Difference. There is no explicit mention of a registry in the U.S. EPA proposed rule, while the WRI Guidelines specifically mention that a publicly accessible registry be created and maintained.

Similarity. Both the WRI Guidelines and the EU Directive specify that a registry of information about closed sites should be established.

Difference. There is no explicit mention of a registry in the U.S. EPA proposed rule, while the EU Directive specifically mentions that a registry be created and maintained.

CO2 composition/definition

The WRI Guidelines text outlines quantity of potential co-constituents on a percent volume basis. A future action is to compare these with criteria listed under 40 CFR part 261.

 

Throughout the WRI Guidelines it is stated that materials should be fit-for-purpose, or designed to function according to specific conditions and parameters, reflecting the flexibility in choosing materials and procedures based on the level of co-constituents in the injected CO2 (see definitions).

The rule does not apply to streams that meet the definition of a hazardous waste under 40 CFR part 261 (see definitions).

A CO2 stream shall consist overwhelmingly of carbon dioxide. A  CO2 stream may contain incidental associated substances from the source, capture or injection process, and trace substances added to help monitor and verify CO2 migration. Concentrations of all incidental and added substances shall be below levels that would adversely affect the integrity of the storage site or the relevant transport infrastructure, pose a significant risk to the environment or human health, and breach the requirements of applicable community legislation. 

The operator should only accept and inject the CO2 stream if analysis of the stream composition including corrosive substances and a risk assessment has been carried out, and if the risk assessment has shown that the contamination levels are in line with the composition criteria referred to in the Directive (Article 16).

Similarity. The WRI Guidelines call for a future action of evaluating the composition of CO2 from various capture processes with the criteria under 40 CFR part 261, and the proposed EPA rule states that the rule does not apply to CO2 streams that meet the definition of a hazardous waste under 40 CFR part 261.

Similarity. Both the WRI Guidelines and the EU Directive acknowledge that trace amounts of co-constituents may be present in the gas stream and focus on project and material design that avoids adverse impacts.

Similarity. Both the U.S. EPA and the EU call for a stream that does not include large quantities of co-constituents; however, the differences in the language may have legal implications.

Constraints on constituents in CO2 stream

Standards for the levels of co-constituents have been proposed by some regulators and legislators; however there is potential risk of reducing sources of anthropogenic CO2 if the standard is too stringent.  Ultimately, the emphasis should be on employing materials, procedures, and processes that are fit-for-purpose and assessing the environmental impacts of any co-constituents along with the benefits of CO2 emissions reduction as part of a comprehensive CCS risk assessment. Facility operators, regulators, and other stakeholders should pay particular attention to potential impacts of co-constituents in the transport and storage aspects of the project (Capture Guideline 1c).

 

The rule does not apply to streams that meet the definition of a hazardous waste under 40 CFR part 261 (see definitions).

The EU Directive necessitates imposing constraints on the composition of the CO2 stream that are consistent with the primary purpose of geologic sequestration (isolating CO2 emissions from the atmosphere), and that are based on the risks that contamination may pose to the safety and security of the transport and storage network and to the environment and human health. Composition of the CO2 stream should be verified prior to injecting and storing it. The composition of the CO2 stream is the result of the processes at the capture installations. Following inclusion of capture installations, an environmental impact assessment has to be carried out in the capture permit process. The best available techniques to improve the composition of CO2 stream have to be established and applied (Section 27) .

 

 

Similarity. Neither the WRI Guidelines nor the U.S. EPA rule provide specific limits on co-constituents that may be present in the captured CO2 stream.

 

Difference. The U.S. EPA rule does not include explicit evaluation of the environmental impacts of the co-constituents as part of a risk assessment.

 

 

Similarity. Although the WRI Guidelines state that there is a potential of setting standards for CO2 composition that are too stringent and the EU Directive speaks to imposing constraints, the resulting language is extremely consistent and states that environmental impacts of co-constituents should be evaluated within a risk analysis framework.

Similarity. Neither the U.S. EPA rule nor the EU Directive provide specific limits on co-constituents that may be present in the captured CO2 stream.

 

Difference. The U.S. EPA rule does not include explicit evaluation of the environmental impacts of the co-constituents as part of a risk assessment.

Faults

Operators should identify and map all potentially significant transmissive faults, especially those that transect the confining zone within the project footprint (Storage Guideline 5b5).

The confining zone should be free of transmissive faults or fractures (defined as faults or fractures with sufficient permeability and vertical extent to allow fluids to move between formations) (§146.83).

Characterization includes development of a 3-dimensional static geological earth model that characterizes storage complex in terms of the presence of any faults or fractures, fault/fracture sealing, and presence of any human-made pathways (Annex 1, Step 2, c).

Difference. The WRI Guidelines specify that all potentially significant transmissive faults be identified and mapped, especially any that transect the confining zone, while the U.S. EPA proposed rule specifies that the confining zone should be “free of” transmissive faults or fractures.

Difference. The WRI Guidelines specify that all potentially significant transmissive faults be identified and mapped, especially any that transect the confining zone, while the EU Directive simply states that the faults/fractures (as well as any expected fault/fracture sealing) be included in the geological model.

Difference. The U.S. EPA rule specifies that the confining zone should be “free of” transmissive faults or fractures, while the EU Directive allows for the presence of faults and fractures, provided they are included in the geological model.

Volumetric capacity

Operators should estimate or obtain estimates of pore volume with site-specific data for the project footprint. This should include all target formations of interest, including primary and secondary targets. Capacity calculations should include estimates of net vertical volume effectively utilized or available for storage and an estimate of likely pore volume fraction to be used (Storage Guideline 5d1).

Capacity estimates are implicit in the description of “area of review” determination, but are not required explicitly.

Data collection includes “Reservoir engineering (including volumetric calculations of pore volume for CO2 injection and ultimate storage capacity, pressure and temperature conditions, pressure volume behaviour as a function of formation injectivity, cumulative injection rate and time)” (Annex 1, Step 1).

Difference. In the U.S. EPA draft rule, capacity estimates are only required implicitly as part of an “area of review” calculation and in the UIC context, which requires adequate pore volume for storage. By stating capacity estimates as an explicit requirement, the WRI Guidelines provide a more direct tie to the capture component of a CCS effort with an implicit need to prove availability of the needed capacity. This difference may be an artifact of difference in scope, with the U.S. EPA rule exclusively focusing on the storage aspects of a project.

 

Similarity. Estimating capacity as part of site characterization is emphasized in both the WRI Guidelines and the EU Directive, with a specific mention of volumetric capacity estimates. By stating capacity estimates as an explicit requirement, the WRI Guidelines and EU Directive provide a direct tie to the capture component of a CCS effort with an implicit need to prove availability of the needed capacity.

Difference. In the U.S. EPA draft rule, capacity estimates are only required implicitly as part of an “area of review” calculation and in the UIC context, which requires adequate pore volume for storage. By stating capacity estimates as an explicit requirement, the EU Directive provides a more direct tie to the capture component of a CCS effort with an implicit need to prove availability of the needed capacity. This difference may be an artifact of difference in scope, with the U.S. EPA rule exclusively focusing on the storage aspects of a project.

 

Injection pressures

Injection pressures and rates should be determined by well tests. Injection formation parting pressure should not be restricted by a regulatory framework but may be adopted as a best practice for early projects (Storage Guideline 6j).

Except during stimulation, the owner or operator must ensure that injection pressure does not exceed 90 percent of the fracture pressure of the injection zone (§146.88). The preamble states that U.S. EPA is seeking comments on this.

Fracture pressure is mentioned as a data collection requirement; no restriction is set (Annex 1, Step 1).

Difference. In this case, the WRI Guidelines and U.S. EPA Rule directly disagree. The U.S. EPA draft rule states that operators cannot exceed 90% of the fracture pressure while the WRI Guidelines state that a regulatory framework should not restrict injections above formation parting or fracture pressures. The key question, and one that may require further research to answer, is whether the available storage space would be significantly decreased by and whether certain cap rocks would fail at >90% injection pressure.

 

Similarity. Both the WRI Guidelines and the EU Directive include fracture pressure as a data requirement without setting explicit standard limits.

 

Difference. The EU Directive does not include a limit to injection pressures, but does include reporting fracture pressure as a data requirement. The U.S. EPA draft rule states that operators cannot exceed 90%. The key question, and one that may require further research to answer, is whether the available storage space would be significantly decreased by and whether certain cap rocks would fail at >90% injection pressure.

 

Post-closure

This is defined as the period of time after certification of site closure. At this stage, the storage project should not endanger human health or the environment. The Guidelines propose a set of expectations for a site in the post-closure period, as well as potential mechanisms for managing post-closure MMV activities, to the extent needed (see definitions).

Post-injection site care means appropriate monitoring and other actions (including corrective action) are needed following cessation of injection to ensure that USDWs are not endangered, as required under §146.93 (see definitions).

'Post-closure' means the period after the closure of a storage site, including the period after the transfer of responsibility to the competent authority (Article 3, definition 19).

Difference. The WRI Guidelines have identified post-closure as a period after a demonstration of non-endangerment has been made and after the point at which the operator is no longer responsible for MMV, while the U.S. EPA defines post-closure as a period of time after injection, but before a site is closed, during which the operator is responsible for MMV. Clearly defined criteria for cessation of monitoring and transfer of responsibility are essential (regardless of what label is given to any one period of time).

 

Difference. The WRI Guidelines have identified post-closure as a period after a demonstration of non-endangerment has been made and after the point at which the operator is no longer responsible for MMV, while the EU Directive defines the time period of post-closure to include time after a site is closed, and before and after responsibility of the site is transferred.

Difference. The U.S. EPA defines post-closure as a period of time after injection, but before a site is closed, during which the operator is responsible for MMV, while under the EU Directive the time period of pos-closure includes time after a site is closed, and before and after responsibility of the site is transferred.

Transfer of responsibility

Project operators who have demonstrated non-endangerment should be released from responsibility for any additional post-closure MMV and should plug and abandon any wells used for post-injection monitoring. At this point, the project can be certified as closed and project operators should be released from any financial assurance instruments held for site closure. In the event that regulators or a separate entity decide to undertake post-closure monitoring that involves keeping an existing monitoring well open or drilling new monitoring wells, project operators should not be responsible for any such work or associated mitigation or remediation arising out of the conduct of post-closure MMV (Storage Guideline 7e).

 

Certified closed sites should be managed by an entity or entities whose tasks would include activities such as operating registries of sites; conducting periodic MMV; and, if the need arises, conducting routine maintenance at MMV wells at closed sites over time (Storage Guideline 8a).

A site is only closed after a default 50-year post-closure monitoring and site closure plan is complete. No transfer is mentioned, but the operator has completed obligations at site closure (which is after the post-injection monitoring period) (§146.93).

After a storage site has been closed, the operator should remain responsible for maintenance, monitoring and control, reporting, and corrective measures pursuant to the Directive on the basis of a post-closure plan… until the responsibility for the storage site is transferred to the competent authority. Liability will be transferred to the competent authority on its own initiative or on the request of the operator upon completion of the following conditions:

-            All evidences indicate that the CO2 will be permanently and completely contained.

-            A minimum period, to be determined by the competent authority, has elapsed. This minimum period shall be no shorter than 20 years, unless the competent authority is convinced that the criterion referred to in point (a) is complied with before the end of that period.

-            The financial obligations are complete (as per Article 20).

-            The site is sealed and injection facilities are removed.

After transfer of responsibility, site monitoring should continue and may be reduced to a level that still allows for identification of leakages or significant irregularities, but if leakages or significant irregularities are identified it should be intensified (Article 18).

 

Difference. The WRI Guidelines specify criteria for demonstrating that a site will no longer pose a danger to humans and the environment, at which point it can receive a certification of site closure. The WRI Guidelines also call for creation of an entity that can conduct any needed activities at a closed site, while the U.S. EPA does not clearly define what happens to a site after the default 50-year post-closure monitoring and permanent closure of the site.

 

Similarity. The EU Directive provides the most clarity on the transfer of responsibility and outlines the criteria an operator would need to meet to enable transfer to the “competent authority,” including a default 20-year waiting period. This is consistent with the language in the WRI Guidelines that specifies criteria for demonstrating that a site will no longer pose a danger to humans and the environment, at which point it can receive a certification of site closure. The WRI Guidelines also call for the creation of an entity that can conduct any needed activities at a closed site.

 

Difference. The WRI Guidelines differ from the EU Directive in that they allow for these activities to include MMV, and that they do not specify a default time period prior to transfer.

Difference. The U.S. EPA does not clearly define what happens to a site after the default 50-year post-closure monitoring and permanent closure of the site. The EU Directive provides the most clarity on the transfer of responsibility and outlines the criteria an operator would need to meet to enable transfer to the “competent authority,” including a default 20-year waiting period.

 

Monitoring duration

A site is closed when criteria for non-endangerment have been demonstrated and at that time the operator is no longer responsible for MMV. However, language leaves open the possibility for longer-term MMV. In the event that regulators or a separate entity decide to undertake post-closure monitoring that involves keeping an existing monitoring well open or drilling new monitoring wells, project operators should not be responsible for any such work or associated mitigation or remediation arising out of conduct of post-closure MMV (Storage Guideline 7d, 7e).

The owner or operator shall continue to conduct monitoring as specified in the Director-approved post-injection site care and site closure plan for at least 50 years following the cessation of injection. At the Director’s discretion, the monitoring will continue until the geologic sequestration project no longer poses an endangerment to USDWs. An exemption may be granted by the Director (§146.93).

 

“Post-closure monitoring shall be based on the information collected and modeled during the implementation of the monitoring plan.” It shall serve in particular to provide information required for transfer of responsibility. This is to document that the stored CO2 will be completely contained for the indefinite future. The monitoring should continue after the transfer of responsibility but may be reduced to a level that still allows for identification of leakages or significant irregularities. However, if leakages or significant irregularities are identified it should be intensified (Annex II; Article 18).

 

Difference. In the WRI Guidelines, a storage site is certified as closed when criteria for non-endangerment have been demonstrated and at that time the operator is no longer responsible for MMV. However, language leaves open the possibility for longer-term MMV. The U.S. EPA rule calls for monitoring to take place until the plume stabilizes and uses a default period of 50 years for MMV activities, which can be lengthened or shortened at the discretion of the regulator.

Similarity. Both the WRI Guidelines and the EU Directive take a performance-based approach where the operator is required to demonstrate that the storage is secure.

Difference. The WRI Guidelines would allow for some MMV to continue after the site closure certification determination is made, under the auspices of the entity that is responsible for the site during the post-closure phase. Also, under the EU Directive it is likely that monitoring would continue for the minimum waiting period of 20 years post-injection prior to transfer of responsibility.

 

Difference. The U.S. EPA rule calls for monitoring to take place until the plume stabilizes and uses a default period of 50 years for MMV activities, which can be lengthened or shortened at the discretion of the regulator. The EU Directive specifies that post-closure monitoring should be focused on obtaining the information needed and identified in the plan. This would continue for at least the minimum waiting period of 20 years post-injection prior to transfer of responsibility.

Phased permitting

The WRI Guidelines provide no recommendation for or against phased permitting.

The draft rule requires submittal and periodic re-evaluation of several types of plans, but does not specify a phased permit structure.

Exploration and storage permits are distinct with unique requirements for each (Chapter 2, Chapter 3).

Similarity. Phased permits are not mentioned in either the Guidelines or the EPA proposed rule, although some states do require separate permits for characterization and injection.

Difference. The EU Directive outlines clearly that permits for site characterization (or exploration) should be issued separately from permits for site storage, while the WRI Guidelines do not address this point.

Difference. The EU Directive outlines clearly that permits for site characterization (or exploration) should be issued separately from permits for site storage, while the U.S. EPA rule does not address this point.

Cement requirements

The cement in the well should extend from the injection zone to at least an area above the confining zone (Storage Guideline 6g).

Surface casing must extend through the base of the lowermost USDW to the surface; one long string casing must extend to the injection zone and be cemented to surface in one or more stages (§146.86).  

The EU Directive contains no language specific to well construction or cement requirements.

Difference. There is a notable difference between the WRI Guidelines and U.S. EPA’s draft rule regarding well construction requirements, specifically on the topic of cementing. The U.S. EPA rule requires long string casing to be cemented to the surface, while the WRI Guidelines specify extending the casing to at least an area above the confining zone. A number of stakeholders felt cementing to the surface should not be required at present because the literature is unclear. Future work should clarify the optimal well construction for permanent geologic storage.

Difference. The EU Directive does not prescribe construction techniques and cannot offer a basis for comparison with the recommendations proposed by the WRI Guidelines.

Difference. The EU Directive does not prescribe construction techniques and cannot offer a basis for comparison with the recommendations proposed by the U.S. EPA proposed rule.