The EU has set out a goal to become climate neutral by 2050. The IPCC has recognized carbon dioxide removal (CDR) as being an essential technology in order to achieve net zero CO2 emissions. Since CDR can account for emissions from sectors that are hard to mitigate, the European Commission has proposed a regulation that will be the first EU-wide voluntary certification framework for high-quality carbon removals. During 1 December 2023 - 23 March 2023, the proposal received feedback from different actors in order to develop methodologies that will enable stakeholders to implement this certification framework. Therefore, since relevant actors' participation in designing the framework is important, the aim of this study is to analyse the feedback and identify potential strengths, weaknesses, areas of agreement, and conflicts of interest in the proposal. Out of the 210 submitted feedback documents that the EU Commission received, 165 documents were analysed in this study. From the feedback, the results of this study show that many actors from different sectors welcome the proposal and believe that it could bring further transparency and trustworthiness to CDR activities which could increase investments in carbon removal solutions. However, a common weakness among the respondents was the lack of clarity in the framework regarding the terminology and the alignment to other regulations and policies. Some conflicts of interest were also identified, surrounding the level of permanence in the included CDR activities, co-benefits, and the representation of actors within the expert groups. / EU har satt ett mål att bli klimatneutralt 2050. IPCC har erkänt koldioxidinfångning som en nödvändig teknik för att uppnå netto noll CO2 utsläpp. Detta eftersom koldioxidinfångning kan kompensera för utsläpp från sektorer som är svåra att minska. Den Europeiska kommissionen har därav föreslagit en ny förordning som kommer att bli det förstaEU-omfattande frivilliga ramverket för certifiering av koldioxidinfångning av hög kvalitet. Den 1 december 2023 - 23 mars 2023 fick förslaget feedback från olika aktörer i syfte att utveckla metoder som gör det möjligt för aktörer att implementera certifieringsramverket. Eftersom att relevanta aktörers deltagande i utformningen av ramverket är av betydelse, är syftet med denna studie att analysera responsen som certifieringsramverket har fått för att sedan kunna identifiera potentiella styrkor, svagheter, punkter av överensstämmelse och intressekonflikter inom förslaget. Av de 210 dokumenten med respons som inkom tillEU-kommissionen, analyserades 165 dokument i denna studie. Efter att responsen analyserats framkom det att många aktörer från olika sektorer välkomnar förslaget då de, bland annat, anser att förslaget skulle kunna tillföra ytterligare transparens och trovärdighet gällande koldioxidinfångning. Detta skulle i sin tur kunna öka andelen investeringar i olika tekniker för koldioxidinfångning. En svaghet som framkom bland respondenterna var att terminologin i ramverket ansågs vara otydlig. Respondenterna ansåg även att det var otydligt hur ramverket skulle anpassas till befintliga och kommande policys och lagar. Vissa intressekonflikter kunde också identifieras. Både kring koldioxidlagringens varaktighet och ramverkets samfördelar samt representationen av aktörer inom expertgupperna.

Geological sequestration of CO₂ in deep saline reservoirs is one of the ways to reduce its continuous emission into the atmosphere to mitigate the greenhouse effect. The effectiveness of any CO₂ sequestration operation depends on pore volume and the sequestration efficiency of the reservoir. Sequestration efficiency is defined here as the maximum storage with minimum risk of leakage to the overlying formations or to the surface. This can be characterized using three risk parameters i) the time the plume takes to reach the top seal; ii) maximum lateral extent of the plume and iii) the percentage of mobile CO₂ present at any time. The selection among prospective saline reservoirs can be expedited by developing some semi-analytical correlations for these risk parameters which can be used in place of reservoir simulation study for each and every saline reservoir. Such correlations can reduce the cost and time for commissioning a geological site for CO₂ sequestration. To develop such correlations, a database has been created from a large number of compositional reservoir simulations for different elementary reservoir parameters including porosity, permeability, permeability anisotropy, reservoir depth, thickness, dip, perforation interval and constant pressure far boundary condition. This database is used to formulate different correlations that relate the sequestration efficiency to reservoir properties and operating conditions. The various elementary reservoir parameters are grouped together to generate different variants of gravity number used in the correlations. We update a previously reported correlation for time to hit the top seal and develop new correlations for other two parameters using the newly created database. A correlation for percentage of trapped CO₂ is also developed using a previously created similar database. We find that normalizing all risk parameters with their respective characteristic values yields reasonable correlations with different variants of gravity number. All correlations confirm the physics behind plume movement in a reservoir. The correlations reproduce almost all simulation results within a factor of two, and this is adequate for rapid ranking or screening of prospective storage reservoirs. CO₂ injection in saline reservoirs on the scale of tens of millions of tonnes may result in fracturing, fault activation and leakage of brine along conductive pathways. Critical contour of overpressure (CoP) is a convenient proxy to determine the risk associated with pressure buildup at different location and time in the reservoir. The location of this contour varies depending on the target aquifer properties (porosity, permeability etc.) and the geology (presence and conductivity of faults). The CoP location also depends on relative permeability, and we extend the three-region injection model to derive analytical expressions for a specific CoP as a function of time. We consider two boundary conditions at the aquifer drainage radius, constant pressure or an infinite aquifer. The model provides a quick tool for estimating pressure profiles. Such tools are valuable for screening and ranking sequestration targets. Relative permeability curves measured on samples from seven potential storage formations are used to illustrate the effect on the CoPs. In the case of a constant pressure boundary and constant rate injection scenario, the CoP for small overpressures is time-invariant and independent of relative permeability. Depending on the relative values of overall mobilities of two-phase region and of brine region, the risk due to a critical CoP which lies in the two-phase region can either increase or decrease with time. In contrast, the risk due to a CoP in the drying region always decreases with time. The assumption of constant pressure boundaries is optimistic in the sense that CoPs extend the least distance from the injection well. We extend the analytical model to infinite-acting aquifers to get a more widely applicable estimate of risk. An analytical expression for pressure profile is developed by adapting water influx models from traditional reservoir engineering to the "three-region" saturation distribution. For infinite-acting boundary condition, the CoP trends depend on same factors as in the constant pressure case, and also depend upon the rate of change of aquifer boundary pressure with time. Commercial reservoir simulators are used to verify the analytical model for the constant pressure boundary condition. The CoP trends from the analytical solution and simulation results show a good match. To achieve safe and secure CO₂ storage in underground reservoirs several state and national government agencies are working to develop regulatory frameworks to estimate various risks associated with CO₂ injection in saline aquifers. Certification Framework (CF), developed by Oldenburg et al (2007) is a similar kind of regulatory approach to certify the safety and effectiveness of geologic carbon sequestration sites. CF is a simple risk assessment approach for evaluating CO₂ and brine leakage risk associated only with subsurface processes and excludes compression, transportation, and injection-well leakage risk. Certification framework is applied to several reservoirs in different geologic settings. These include In Salah CO₂ storage project Krechba, Algeria, Aquistore CO₂ storage project Saskatchewan, Canada and WESTCARB CO₂ storage project, Solano County, California. Compositional reservoir simulations in CMG-GEM are performed for CO₂ injection in each storage reservoir to predict pressure build up risk and CO₂ leakage risk. CO₂ leakage risk is also estimated using the catalog of pre-computed reservoir simulation results. Post combustion CO₂ capture is required to restrict the continuous increase of carbon content in the atmosphere. Coal fired electricity generating stations are the dominant players contributing to the continuous emissions of CO₂ into the atmosphere. U.S. government has planned to install post combustion CO₂ capture facility in many coal fired power plants including W.A. Parish electricity generating station in south Texas. Installing a CO₂ capture facility in a coal fired power plant increases the capital cost of installation and operating cost to regenerate the turbine solvent (steam or natural gas) to maintain the stripper power requirement. If a coal-fired power plant with CO₂ capture is situated over a viable source for geothermal heat, it may be desirable to use this heat source in the stripper. Geothermal brine can be used to replace steam or natural gas which in turn reduces the operating cost of the CO₂ capture facility. High temperature brine can be produced from the underground geothermal brine reservoir and can be injected back to the reservoir after the heat from the hot brine is extracted. This will maintain the reservoir pressure and provide a long-term supply of hot brine to the stripper. Simulations were performed to supply CO₂ capture facility equivalent to 60 MWe electric unit to capture 90% of the incoming CO₂ in WA Parish electricity generating station. A reservoir simulation study in CMG-GEM is performed to evaluate the feasibility to recycle the required geothermal brine for 30 years time. This pilot study is scaled up to 15 times of the original capacity to generate 900 MWe stripping system to capture CO₂ at surface. / text