IMPACTS: Economic Trade-offs for CO2 Impurity Specification

Key findings and recommendations from the IMPACTS project

Carbon capture and storage (CCS) has been identified as a priority issue within the context of the North American climate change and energy collaboration. An important aspect of CCS is the need to improve public confidence in long-term geological storage of CO2. A key to developing confidence for the longer term is a demonstration of safe and expected storage behaviour in the short term. Two primary concerns of the public and government regulatory bodies are the potential for induced seismicity and for CO2 leakage. To alleviate these concerns, storage monitoring is critical in demonstrating that the subsurface CO2 plume is behaving as expected, and that induced microseismic or seismic activity is being closely monitored. The Aquistore CO2 Storage Project is a multi-year research and monitoring project to demonstrate that storing CO2 deep underground is a safe and workable solution to help reduce greenhouse gas emissions to the atmosphere. The Geological Survey of Canada's studies within the project are focused on the development of improved monitoring methodologies and a better understanding of the relationship between CO2 injection and induced seismicity. A total of 60 ktonnes of CO2 were injected at the Aquistore site in the first year following initial injection in April-2015. Injection is occurring within a saline formation at a depth of 3150-3350m. In the first 4 months of 2016, CO2 was injected at an average rate of ~400 tonnes/day. Passive seismic monitoring at the site which began in 2012 has not identified any seismicity associated with the injection process. The first time-lapse 3D seismic surveys were completed in February of 2016 and will provide images of the CO2 plume in the subsurface.

Geochemistry of anhydrites at the iea Weyburn site: Implications for assessing the effectiviness of sealing rocks

The steady accumulation of greenhouse gases resulting from the combustion of fossil fuels has led to an increase in the amount of solar radiation trapped between the atmosphere and earth. This increased radiation raises the temperature of the earth's atmosphere and ocean systems. It is believed that continuing increases in temperature will lead to catastrophic changes in weather conditions around the globe. With carbon dioxide (CO2) being the most abundant greenhouse gas, many efforts are underway to reduce the level of CO2 entering the atmosphere. One promising technology involves the sequestration of CO2 in deep geologic formations. CO2 is first separated from flue gas expelled by coal fired power plants, compressed to a supercritical phase (ScCO2), and injected into underground formations such as exhausted gas reservoirs and deep brine aquifers. Flue gas normally contains 10% to 15% CO2 by volume. It is believed that CO2 can remain permanently sequestered in such formations, depending on the chemical and mechanical characteristics of the underground resident water and rock constituents. However, uncertainties remain in several areas such as the chemical and physical effects of CO2 injection on subsurface rocks which may introduce unwanted side-effects that could hamper long-term sequestration, such as induced seismicity. Risk estimation of short- and long-term geologic storage of CO2 can only be addressed through numerical modeling and simulation. In this paper we examine a short-term side-effect of CO2 injection in which an acidic fluid region develops ahead of the main CO2-rich water injectant. It is shown that the length of this low pH region varies with injectant velocity and reservoir temperature. A leading fluid region of low pH could have an effect on the wetability of formation minerals and the capillarity of the moving effluent. An advancing low pH front may increase the wetability of mineral surfaces which would improve CO2 sequestration efficiency and aid in enhanced oil recovery operations.

Influence of SO2 on CO2 storage for CCS technology: Evaluation of CO2/SO2 co-capture

Assessment of two-phase flow on the chemical alteration and sealing of leakage pathways in cemented wellbores

Introduction Carbon Capture and Sequestration (CCS) is one of the most promising technologies for the reduction of CO2 accumulation in the atmosphere. Continuous research on the topic develops methods for utilising the captured CO2 for enhanced oil and gas recovery (EOR and EGR). Through the research in this field, challenges that regard the mitigation of environmental pollutants such as CO2, as well as the increase of efficiency of oil and gas production processes can be addressed. Quite an important role in the design of these processes, and especially for the transport of CO2 streams via pipelines, is held by the thermodynamic modeling of pure CO2 and CO2 mixtures. The stream in the pipeline contains mainly CO2, together with many other gases, depending on the source of the stream, and the capture technology that precedes the transport. Typical impurities include CH4, N2, O2, SO2, Ar, and H2S, all of which can have a substantial impact on the thermodynamic behavior of the stream, both in the pipeline and out of it, in the unwanted event of a fracture. Methodology In this work, cubic and SAFT-based equations of state are used in combination with specific models for the calculation of phase equilibria, derivative thermodynamic properties and transport properties of CO2 mixtures. Their performance is evaluated against available experimental data from the literature. Especially for transport properties, established viscosity models from the literature based on friction theory, are combined with the above mentioned equations, in order to assess their ability of predicting viscosity of CO2 mixtures of interest to the CCS and EOR processes. Diffusivity and thermal conductivity are also investigated with the use of models combined with a range of equations of state, towards a unified approach of the thermodynamic properties prediction for CO2 containing systems. Conclusion In most cases, the higher order EoS are more accurate than the cubic EoS in the case of predictive calculations (no binary parameters used) of phase equilibria. Nevertheless, the two classes of EoS provide similarly good results when using a temperature independent binary interaction parameter. Derivative properties are more accurately captured by the SAFT family EoS, due to the higher physical content that they have over the cubic EoS. The pure components viscosity calculations with the different types of EoS compared in this study do not exhibit great deviations, owing that to the fitting procedure that was necessary for each EoS. On a related note, the need for more experimental data of derivative and transport properties of CO2 mixtures at conditions that cover the design and operation of CO2 pipelines becomes obvious. Acknowledgment The authors acknowledge financial support from the 7th European Commission Framework Program for Research and Technological Development for the projects "Quantitative failure consequence hazard assessment for next generation CO2 pipelines" (CO2PipeHaz, Project No.: 241346) and "Techno-economic Assessment of CO2 Quality Effect on Capture, Transport and Storage" (CO2Quest, Project No.: 309102).

Techno-economic assessment of CO2 quality effect on its storage and transport: CO2QUEST: An overview of aims, objectives and main findings

CO2 transport from capture sources to storage sites is one of the leading parts of the carbon capture, and storage (CCS) infrastructure that needs to be optimized in order to reduce the capital, operating and maintenance (O&M) costs. This paper conducts a systematic overview of CO2 transport and identifies the knowledge gaps with a view for application to optimal CCS Hub design. The findings show that much research has been focused on the engineering and economic consequences in pure CO2 streams while in most real field studies the captured CO2 is accompanied with trace impurities that can affect the "intelligent" cost model's confidence to estimate CO2 pipeline costs. The impacts of different topographical conditions in current models on the economic pressure drop and inlet pressure is another challenge that has received little attention in the literature. Most cost-effective pipeline systems described in the literature, are based on the simple point-to-point design while the capture of CO2 from multiple sources and transport to multiple distributed CCS injection wells is an issue for the industrial-scale rollout of CCS. The lack of sufficient studies on the flow variations within CO2 networks is the last discussion in this research review. Further, there have been several cost models reported in the literature, and most of them are based on the costs of the natural gas pipeline infrastructure. However, the higher operating pressure of CO2 and the various impurities in CO2 streams from capture plant may require construction material specifications that will affect cost models. A systematic understanding of how CO2 pipelines contribute to CCS chain economics is still lacking. While many optimization challenges have been solved for natural gas pipeline networks, there are different thermodynamic behaviors for CO2 that require further optimization. The potential minor impurities that could occur in CO2 pipelines such as water (H2O), nitrogen (N2), oxygen (O2), hydrogen sulfide (H2S) and methane (CH4) can add complexity compared to the transport of natural gas.

A novel process design and techno-economic performance assessment for methanol synthesis from Blast Furnace Gas (BFG) is presented. Methanol synthesis using BFG as a feedstock, based on direct CO2 hydrogenation at commercial scale was simulated using Aspen Plus software to evaluate its technical performance and economic viability. The applied process steps involve first conditioning BFG using adsorption based desulfurisation, water-gas shift, dehydration, then separation of components into N2, CO2 and H2 rich streams using pressure swing adsorption. The H2 stream and a fraction of the CO2 stream are fed to a methanol synthesis system, while the remaining CO2 may be considered for geological storage in a Carbon Capture, Utilization and Storage (CCUS) case, or not in a Carbon Capture Utilization (CCU) case. Techno-economic analysis confirms methanol production from BFG is economically attractive under certain conditions, with Levelized Cost of Methanol production (LCOMeOH) calculated to be 344.61 £/tonne-methanol, and costs of CO2 avoided of − 20.08 £/tonne-CO2 for the CCU process and 9.01 £/tonne-CO2 for the CCUS process when using a set of baseline engineering assumptions. Sensitivity analysis of the process simulation explores opportunities for optimising the methanol synthesis system in terms of the impact of reactor size and/or recycle ratio on LCOMeOH. Economic viability of the CCU(S) processes is also found to be highly dependent on the cost of the feedstock BFG. Future cost savings as compared to business-as-usual steel production by 2030 in consideration of expected increases in the carbon price are estimated to be 10.59 £/tonne-steel for CCU and 24.61 £/tonne-steel for CCUS.

The production of hydrogen through water electrolysis has emerged as a promising alternative to decarbonizing the energy sector, especially when integrated with renewable energy sources. Among the key operational parameters that affect electrolysis performance, temperature and current density play a critical role in determining the energy efficiency, hydrogen yield and durability of the system. The study presents a Systematic Literature Review (SLR) that includes peer-reviewed publications from 2018 to 2025, focusing on the effects of temperature and current density across a variety of electrolysis technologies, including alkaline (AEL), proton exchange membrane (PEMEL), and solid oxide electrolysis cells (SOEC). A total of seven high-quality studies were selected following the PRISMA 2020 framework. The results show that high temperatures improve electrochemical kinetics and reduce excess potential, especially in PEM and SOEC systems, but can also accelerate component degradation. Higher current densities increase hydrogen production rates but lead to lower Faradaic efficiency and increased material stress. The optimal operating range was identified for each type of electrolysis, with PEMEL performing best at 60–80 °C and 500–1000 mA/cm2, and SOEC at >750 °C. In addition, system-level studies emphasize the importance of integrating hydrogen production with flexible generation and storage infrastructure. The review highlights several research gaps, including the need for dynamic modeling, multi-parameter control strategies, and techno-economic assessments. These findings provide a basic understanding for optimizing hydrogen electrolysis systems in low-carbon energy architectures.

The release of CO2 into the atmosphere has been verified as a significant reason for global warming and climate change. To prevent a large amount of CO2 from being emitted into the atmosphere, its utilization and storage become very important for human survival. Regarding the utilization of CO2 in oil reservoir engineering practice, CO2 enhanced oil recovery (CO2EOR) as a mature technology has been widely applied in several types of reservoirs, such as sandstone, carbonate, and shale gas/oil reservoirs, and scientists and reservoir engineers aim to improve displacement efficiency with different injection modes and study its influencing factors over the past few decades. However, related to the experimental evaluation of storage capacity potential with the CO2EOR displacement mode and the long-term storage of CO2 in situ in the formation experienced by CO2 flooding is rarely studied experimentally. In this study, we investigated the effect of injection mode and reservoir heterogeneity on CO2EOR and its storage potential. Several core flooding experiments on displacing remaining oil and water by scCO2 after water flooding have been performed, including injection modes, which are horizontal, vertical, and tapered WAG injections, using reservoir carbonate rock, live crude oil, and seawater under reservoir conditions. The dual-core core flooding experiment was used to study the effect of reservoir heterogeneity on scCO2 storage capacity. As a result of this study, the previously proposed experimental methodology was used to calculate the scCO2 storage capacity, which involved that the scCO2 dissolves into residual water and oil after scCO2 injection, and evaluate the CO2 storage capacity efficiency for different injection modes. The vertical-continuous injection mode of scCO2 flooding can maximize the process of its storage advantage. This study found that the main scCO2 storage mechanism is mainly pore storage (structural trapping) for depleted oil reservoirs. Based on experimental results, the storage efficiency is related permeability of rocks, which expresses the logarithmic relation and increases with an increase in air permeability. The experimental results show that the scCO2 injectivity is not strongly affected, although the relative permeability to scCO2 decreased somewhat after the scCO2EOR process. In addition, the effect of rock heterogeneity on scCO2 storage efficiency is also discussed. The highlights of this study are that the comparison of the scCO2 storage potential was made based on experimental results of different injection modes, and improving the displacement efficiency in the low permeable zone also increases scCO2 storage efficiency. Furthermore, the experimental results can be applied directly to be helpful for the evaluation and strategy of scCO2 storage and can be used to simulate the performance during the injection process of scCO2 storage.

Direct electrification and hydrogen utilization represent two key pathways for decarbonizing the glass industry, with their effectiveness subject to adequate furnace design and renewable energy availability. This study presents a techno-economic assessment for optimal solar energy integration in a representative 300 t/d oxyfuel container glass furnace with a specific energy consumption of 4.35 GJ/t. A mixed-integer linear programming formulation is developed to evaluate specific melting costs, carbon emissions, and renewable energy self-consumption and self-production rates across three scenarios: direct solar coupling, battery storage, and a hydrogen-based infrastructure. Battery storage achieves the greatest reductions in specific melting costs and emissions, whereas hydrogen integration minimizes electricity export to the grid. By incorporating capital investment considerations, the study quantifies the cost premiums and capacity requirements under varying decarbonization targets. A combination of 30 MW of solar plant and 9 MW of electric boosting enables the realization of around 30% carbon reduction while increasing total costs by 25%. Deeper decarbonization targets require more advanced systems, with batteries emerging as a cost-effective solution. These findings offer critical insights into the economic and environmental trade-offs, as well as the technical constraints associated with renewable energy adoption in the glass industry, providing a foundation for strategic energy and decarbonization planning.

High Voltage Direct Current (HVDC) technology is a cornerstone of efficient Offshore Wind Farm (OWF) power transmission. This review examines the integration of HVDC technology in OWFs, considering collection and transmission aspects. The analysis is structured around four key dimensions: economic considerations, connection topologies, converter designs, and technical modeling. It begins with an in-depth economic analysis, evaluating cost-effectiveness, reliability, and market dynamics, focusing on investment, operational costs, and lifecycle expenses. Building on this foundation, the review explores various collection and transmission architectures, highlighting their technical and economical trade-offs, and evaluates power converter designs for efficiency, reliability, and offshore adaptability. Finally, advanced modeling and simulation techniques are reviewed to optimize system performance, enhance reliability, and balance computational efficiency. Throughout each of the four sections, economic and technical constraints are considered together. This helps to improve understanding of how systems can be designed in a way that meets the constraints of both fields and to enhance feasibility on both dimensions. These insights provide a holistic framework for sustainable and economically viable Offshore Wind Energy (OWE) integration.

CO2QUEST: Techno-economic Assessment of CO2 Quality Effect on Its Storage and Transport