CO2 Pipeline Transport Research Articles

Integrity and Safety Management Challenges of Supercritical CO2 Pipeline Transportation at Offshore Platforms

Integrity and Safety Management Challenges of Supercritical CO2 Pipeline Transportation at Offshore Platforms

Techno-Economic Feasibility Analysis of Post-Combustion Carbon Capture in an NGCC Power Plant in Uzbekistan

As natural gas-fired combined cycle (NGCC) power plants continue to constitute a crucial part of the global energy landscape, their carbon dioxide (CO2) emissions pose a significant challenge to climate goals. This paper evaluates the feasibility of implementing post-combustion carbon capture, storage, and utilization (CCSU) technologies in NGCC power plants for end-of-pipe decarbonization in Uzbekistan. This study simulates and models a 450 MW NGCC power plant block, a first-generation, technically proven solvent—MEA-based CO2 absorption plant—and CO2 compression and pipeline transportation to nearby oil reservoirs to evaluate the technical, economic, and environmental aspects of CCSU integration. Parametric sensitivity analysis is employed to minimize energy consumption in the regeneration process. The economic analysis evaluates the levelized cost of electricity (LCOE) on the basis of capital expenses (CAPEX) and operational expenses (OPEX). The results indicate that CCSU integration can significantly reduce CO2 emissions by more than 1.05 million tonnes annually at a 90% capture rate, although it impacts plant efficiency, which decreases from 55.8% to 46.8% because of the significant amount of low-pressure steam extraction for solvent regeneration at 3.97 GJ/tonne CO2 and multi-stage CO2 compression for pipeline transportation and subsequent storage. Moreover, the CO2 capture, compression, and transportation costs are almost 61 USD per tonne, with an equivalent LCOE increase of approximately 45% from the base case. This paper concludes that while CCSU integration offers a promising path for the decarbonization of NGCC plants in Uzbekistan in the near- and mid-term, its implementation requires massive investments due to the large scale of these plants.

Preparation and pipeline transport of CO2 as a hydrate slurry – Modelling and techno-economic analysis

CO2 transportation as a hydrate slurry is modelled in Aspen Plus, including the slurry preparation and the pipeline transport. Due to the lack of built-in models for the hydrate formation, mass and energy balances were developed and implemented using a User-block function. NRTL-RK global property method was used, given the accuracy in predicting the CO2 solubility in water under incipient hydrate formation conditions and the dissolution heat of CO2 in water. The conventional process of transporting CO2 in a supercritical state was also modelled to benchmark the hydrate-based technology. The hydrate-based process is safer than the conventional process as it requires lower operating pressures, but the estimated costs are higher due to the need for refrigeration and larger pipeline diameters for transportation. The addition of thermodynamic promoters, that moderate the hydrate formation conditions, the integration of cold streams with other processes, and valuing the water transported with CO2, will enhance the economic attractiveness of the hydrate-based process.

Study on the effect of valve openings and multi-stage throttling structures on the pressure and temperature during CO2 pipeline venting processes

The venting operation is an important measure for rapidly eliminating the risk of overpressure in CO2 transportation pipelines. However, the low-temperature phenomenon and vibration generated by the rapid discharge can affect structural reliability. Multi-stage throttle structures have been proven to effectively alleviate vibration phenomena, but their impact on low temperatures remains unclear. In this study, venting tests were conducted on eight groups of single-stage and two-stage throttle structures based on a large-scale pipeline. The results indicate that the nonlinear variation of the valve resistance coefficient when the valve opening changes is the fundamental reason affecting the downstream temperature. Two-stage throttle structures can effectively mitigate the low-temperature conditions in certain spaces within the pipeline. For the remaining low-temperature sections, three-stage throttle structures can provide effective compensation. However, this significantly reduces the pressure drop rate in the main pipeline, contradicting the original purpose of the venting operation. Additionally, considering the temperature of the throttle structure and the pressure within the main pipeline, this study recommends increasing the valve openings for the two-stage throttle structure. The results of this study provide important references for the design of throttle structures and the formulation of on-site venting schemes, with strong prospects for engineering applications.

Investigation of scaling-down experiments for accidental CO2 leakage dispersion risks in constant-pressure transportation pipelines within the CCUS process

Within the framework of strategies to prevent global warming, the safety of CO2 transportation pipelines requires thorough hazard analysis. Accidental leakage during long-distance CO2 transport, influenced by the size of the leakage opening, typically occurs under constant pressure conditions in the CCUS process. This paper introduces an innovative scaled experimental apparatus with an elliptical orifice, designed to simulate leakage due to free rupture in pipelines. The goal is to understand the risk characteristics of constant-pressure leakage in transportation pipelines. The results indicate that during leakage, the pressure drop in the source CO2 pipeline is less than 0.3013 MPa/s, which can be considered constant pressure leakage. The Mach disk size dm has a linear relationship with the elliptical leakage orifice ab. The scaled experiments also show that temperatures can drop to as low as −78°C, indicating significant low-temperature risks. This scaling experiment provides a new approach for predicting and mitigating diffusion risks in long-distance pipeline transportation by examining the relationship between pipeline length and orifice diameter. The research data and results contribute to a deeper understanding of the safety aspects of long-distance transportation of CO2 under constant pressure leakage conditions, providing a basis for risk assessment of leakage accidents and environmental protection measures.

Risks and Safety of CO2 Pipeline Transport: A Case Study of the Analysis and Modeling of the Risk of Accidental Release of CO2 into the Atmosphere

In the field of CO2 capture and sequestration, ensuring the safety of pipeline infrastructure is paramount to successful climate change mitigation efforts. This study investigates the dynamics of CO2 dispersion from pipeline systems, assessing not only the transport process but also the physical properties and associated hazards. Advanced simulation techniques are used to model how different states of CO2 (gas, liquid, and supercritical) and varying pipeline characteristics—such as perforation sizes, flow rates, and orientations—affect the dispersion patterns in the event of a leak. Simulations cover a range of atmospheric conditions, emphasizing the role of atmospheric stability and wind speed in shaping dispersion and defining potential impact zones. An analysis of historical pipeline accidents is included to inform risk management strategies. The results show that the orientation of the pipeline has a significant effect on dispersion, with downward leaks causing the largest impact zones, particularly under supercritical conditions. The results highlight the need for adaptive safety strategies that take into account real-time CO2 transport conditions and localized environmental data. By integrating these factors, the study recommends refining safety protocols and emergency response strategies to improve pipeline resilience and public safety against potential leaks. Key findings include the quantification of the relationship between leak parameters and dispersion areas, providing a valuable framework for future safety improvements.

Simulation of boost path and phase control method in supercritical CO2 pipeline commissioning process

CO2 pipeline can be applied to Enhanced Oil Recovery (EOR) projects and CO2 geological storage projects, and has high engineering application value. However, pipeline transportation of CO2 is a high-risk link in CO2 storage projects. The phase state commonly used to transport CO2 is a supercritical state with both gaseous and liquid characteristics, and there are also great challenges in the field of pipeline transportation. The existing researches have carried out a lot of exploration and application development in the heat transfer, phase change, transient and special conditions of supercritical CO2 pipeline operation.In this paper, the modeling and exploration of the commissioning process before the formal operation of the supercritical CO2 pipeline are carried out, and the boost path of the supercritical CO2 pipeline in the phase diagram under different working conditions is obtained. The model developed in this paper is based on the sensitivity analysis of the effects of variables such as ground temperature, filling pressure speed, and whether to perform pressure-stabilizing leak detection operations. The step-up path in the phase diagram of the CO2 pipeline commissioning process and the adjustment control method are obtained. And the critical temperature of each working condition that cannot avoid phase transition, thus contributing to the existing knowledge system in this field.

Investigation of Pipeline CO2 Leakage and Diffusion on Offshore Platforms Based on Numerical Simulation.

Pipeline transportation of CO2 is the key link to realize carbon capture, utilization, and storage. CO2 pipeline transportation may face the risk of leakage, which poses a great threat to the production process and personnel safety. It is of great significance to study the leakage and diffusion characteristics of CO2 in pipeline transportation for the safety design and personnel protection of the offshore CO2 storage platform. In order to study the leakage and diffusion characteristics of CO2 in pipeline transportation on offshore platforms, a physical model of a target platform and several numerical models were built, and a series of pipeline CO2 leakage and diffusion simulations were carried out using the method of numerical simulation. Based on the simulation results, the temperature distribution and CO2 concentration distribution on the offshore platforms after leakage were measured and analyzed. The influence of leakage direction (horizontal and oblique 45° upward) was also studied. Dangerous areas on the platform and suggestions for staff evacuation were given according to the simulation results. The research results of this work can provide guidance for the safe operation of offshore CO2 storage platforms.

A new model to predict the small-hole decompression process of long CO2 pipeline

CO2 pipeline transportation is considered as an economical and safe way of moving large quantities of CO2 in Carbon Capture Utilization and Storage (CCUS) projects. However, design and planning of CO2 pipelines passing through populated areas require careful risk assessment of accidental pipeline failure scenarios leading to CO2 pipeline decompression. In this study, a new zero-dimensional multi-stage outflow model describing transient decompression of CO2 is developed. The model accounts for the experimentally observed liquid level variation along the pipeline and uses the liquid volume fraction threshold parameter (αt) to mark the end of the saturated liquid flow decompression stage. Besides, the Lee model is applied to describe the mass transfer in gas-liquid phases. The model was validated against experimental data obtained large-scale pipeline decompression tests and can be recommended for simulation of outflow of supercritical and liquid CO2 from pipelines longer than 258 m and the orifice-to-pipeline diameter ratios smaller than 0.21. The advantage of this model lies in its use of the relatively simple Vessel Blowdown Model (VBM) to accurately model the depressurization process. It addresses the inconvenience posed by the heavy computational burden of high-dimensional models when predicting long-duration leakages in large-capacity pipelines.

Analysis Model of Crack Arrest for Supercritical CO2 Pipelines Containing Impurities

CO2 transport pipelines, as a critical link in CCUS technology, are more prone to fracture propagation under the effects of environment and high pressure due to the special characteristics of CO2, resulting in ductile fracture incidents. However, the commonly used original Batelle two curves method (BTCM) has large errors applied to CO2 pipelines containing impurities. In this paper, a corrected BTCM based on a hoop stress calibration factor was proposed to evaluate the crack arrest ability of CO2 pipelines. The reliability of the modified model was verified based on the experiments data. The results show that the GERG-2008 equation of state is more suitable in predication of decompression wave velocity, and fracture propagation velocity model with a correction factor of ccf =2.0 was verified in quite good agreement with experiment results. This corrected BTCM that can be directly applied to engineering, provided theoretical basis and suggestions in the design and safe operation of CO2 pipelines containing impurities.

Source-Sink Matching Model Focusing on the Feasibility of CO2 Pipeline Transport

Source-Sink Matching Model Focusing on the Feasibility of CO2 Pipeline Transport

Experimental study of decompression wave characteristics and steel pipe applicability of supercritical CO2 pipeline

High-strength pipeline steel is the optimal choice for continuously transporting large amounts of carbon dioxide (CO2) in the future Carbon capture, utilization and storage (CCUS) industrial chain, and supercritical CO2 (S–CO2) is the ideal phase state from an emitter to an onshore storage site. In CCUS projects, it is very indispensable to carry out the suitability of high steel-grade pipelines to ensure the safe operation of pipelines. It is considered a catastrophic incident for creatures and equipment once pipeline failure when fractures or propagation occurs. In this paper, the fracture propagation velocity of X70, X80, and X90 pipeline materials is calculated base on the high strength line pipe (HLP). Meanwhile, three sets of full-bore fracture (FBR) experiments of S–CO2 pipelines were conducted with similar initial status on an industrial-scale setup, and the decompression wave velocity was obtained with the data acquisition system. The result shows that the initial decompression wave velocity of S–CO2 is about 270 m/s, and the pressure plateau is between 6.8 and 7.3 MPa, corresponding to the decompression wave velocity, which is about in the range of 100–220 m/s. After that, the decompression wave velocity prediction model was established based on the homogeneous equilibrium method (HEM) and the equation of state (Eos), and the prediction results are more conservative than the experimental results. To ensure that the pipeline will not ductilely fracture in the event of a leakage or rupture, X70, X80 and X90 grade steel pipeline design wall thickness and minimum arrest toughness values are determined based on the two-curve method (TCM), respectively. Furthermore, a CO2 pipeline design model is developed based on the experimental data and decompression wave calculation method. The significant experimental data could be used for safety assessment and theoretical model validation in the CO2 transport pipeline and is useful in developing better fracture control models.

Real-time monitoring of CO2 transport pipelines using deep learning

Real-time pipeline monitoring is important for the safe transportation of captured CO2. A dynamic modeling method, which is one of pipeline monitoring methods, can provide reliable diagnostic results for various anomalies. In the dynamic modeling method, anomalies are detected by comparing the predictions and observations of pipeline monitoring variables. However, the licensing costs associated with the use of pipeline flow simulators that provides the predictions are high. In this study, we developed a real-time deep-learning-based pipeline monitoring method that can save the licensing cost of the pipeline flow simulators. The predictions are obtained using deep-learning models where the pipeline flow simulator is required only in the training step. Two improvements were made to enhance both the prediction and anomaly detection accuracies. First, the prediction accuracy for the monitoring variables can be improved by considering a delay time interval between inlet and outlet points in pairing training input and output data. Second, the anomaly detection accuracy can be also improved by conditionally choosing observations based on the normal operation ranges of the observations. As part of a field demonstration, the proposed deep-learning-based pipeline monitoring method was applied to the monitoring of a CO2 transport pipeline located in the East Sea gas field. The results showed the anomaly detection accuracy of the proposed method was improved by more than 25 %.

China's CO2 pipeline development strategy under carbon neutrality

Under China's goal of carbon neutrality, there is a huge demand for carbon dioxide (CO2) capture, utilization, and storage technology (CCUS). CO2 transport, as a crucial link in the CCUS industrial chain, will inevitably rely on the construction of long-distance CO2 pipelines and infrastructure. Due to the late start and small scale of China's CO2 pipeline construction, and the relative lag in related technologies and policies, it is urgent to make systematical planning and achieve relevant technological breakthroughs for the future construction of CO2 pipeline network as a public infrastructure. Therefore, a three-stage pipeline development path is proposed based on the analysis of the spatial distribution characteristics and the temporal pattern of large-scale commercial development of CO2 carbon sources and storage in China. Moreover, solutions and suggestions are proposed upon the developments analysis in China from the perspectives of pipeline transportation technology, safety evaluation, materials and equipment, and integrity. The results show that the construction of CO2 pipeline network as an important CCUS infrastructure will accelerate with the development of the global CCUS industry; the spatial distribution of CO2 emission sources and storage is unbalanced in China, with 65.8% from the eastern and central China, and CO2 flooding and geological storage contributing to most of large-scale CO2 pipeline transportation. The conclusions are as follows. First, the three-stage development path is a million-ton demonstration project of supercritical CO2 transmission pipeline before China peaks carbon emissions. After the achievement of carbon peak, a 10 million-ton regional network architecture of CO2 pipeline network centered on basins will be built, and trunk pipelines between regions will be formed before achieving carbon neutrality, establishing the national carbon transmission network with a transportation capacity of 10 × 108 ton, and a total mileage of approximately 6 × 104 km. Second, we should carry out research on the technology and equipment for the full phase CO2 pipeline transportation onshore and offshore, improve the domestic pipeline transportation technology, and promote the continuous improvement of the regulatory system in the pipeline transportation industry, so as to facilitate the implementation of demonstration projects.

Depressurization of CO2 in a pipe: Effect of initial state on non-equilibrium two-phase flow

It is key in several industrial applications to accurately describe rapid depressurization of liquid and dense phase states. Examples include refrigeration systems, nuclear reactor cooling and CO2 capture and storage (CCS). It is expected that large-scale CO2 pipeline transportation must be deployed as a vital part of reaching net zero emissions by 2050. During rapid depressurization of liquid-like CO2, boiling will in many cases occur out of equilibrium, at a lower pressure than the local saturation pressure. Capturing the non-equilibrium effects is necessary to predict outflow rates and the resulting pressure and temperature inside the pipe. In the present work, we quantify the non-equilibrium effects by studying a series of CO2 pipe depressurization experiments from liquid-like states at initial temperatures from 10°C to 40°C. We compare the experimental results to predictions of the homogeneous equilibrium model (HEM) and a homogeneous relaxation-type non-equilibrium model (HRM*) where the mass-transfer rate from liquid to gas is tuned by a relaxation time. The relaxation time was found to decrease for increasing temperatures, and it was observed to be approximately 60 times longer for the coldest experiment than for the warmest one.

CO2 pipelines release and dispersion: A review

Carbon Capture, Utilization, and Storage (CCUS) is an emerging industry in response to climate change. With this, more pipelines are being built to transport CO2 to sequestration sites. CO2, though non-toxic and non-flammable, is an asphyxiant that can cause death when exposed to high concentrations. Hence, there is a need to evaluate the release and dispersion behavior of CO2 from pipelines. Industrial-scale experiments of CO2 dispersion have been performed to acquire quantitative data. However, the sheer number of scenarios that could possibly occur is difficult to perform one-by-one experimentally. Computational tools, such as Computational Fluid Dynamics (CFD), and risk assessment methodologies, such as Quantitative Risk Assessment (QRA), have then been utilized to predict CO2 dispersion behavior and hazards, respectively. In this review, the different industrial-scale experiments, CFD models for CO2 dispersion, and risk assessment of CO2 transport pipelines were discussed. Moreover, we emphasize the possibility of using machine learning as a tool to increase the accuracy and efficiency in predicting CO2 dispersion behavior. The future direction of predicting CO2 dispersion behavior through the use of machine learning was also explored.

Build more and regret less: Oversizing H2 and CCS pipeline systems under uncertainty

The large-scale deployments of Carbon Capture and Storage (CCS) and hydrogen (H2) require the installation of costly carbon dioxide (CO2) and H2 pipeline infrastructures. As the future demands for CO2 and H2 pipeline transportation are expected to increase substantially, this paper examines the economics of installing adequately oversized infrastructures. We analytically show that the underlying engineering equations de facto define Cobb-Douglas production functions for both fluids. We then use these production functions to determine the cost-minimizing decisions of a pipeline operator and infer the optimal ratio of oversizing. From a policymaking perspective, this ratio indicates whether the level of oversizing envisioned by the operator is consistent with its expectations of future demand (and thus, by contrast, whether it is attempting to overcapitalize and exploit a regulatory flaw). As the anticipations of the operator may fail to materialize, we opt for a minimax regret perspective and compare the performances of the operator's investment decisions under alternative demand trajectories. Our study shows that the conservative recommendation to build for the proven demand only is systematically regret-maximizing. Consequently, an infrastructure push would likely contribute to overcoming the chicken and egg problem and thus support the large-scale deployment of these emerging technologies.

Multi-objective economic and environmental assessment for the preliminary design of CO2 transport pipelines

A methodology based on the multi-objective optimisation of economic and environmental aspects is presented to support the preliminary design of CO2 transport pipelines employed as part of Carbon Capture and Storage (CCS) systems. Pareto optimal design solutions are determined for a realistic point-to-point CO2 pipeline using Level Diagrams and choosing the Nominal Pipe Size (NPS) as a decision variable. A quantitative procedure entailing the definition of economic and environmental key performance indicators is defined to allow the identification of an optimum pipeline design. The outcome is compared against the minimisation of single-objective indicators based on the CO2 avoided and carbon pricing concepts. The results of a case-study concerning a 70 km long pipeline transporting 10 Mt yr−1 of supercritical CO2 show that the multi-objective method yields an optimum NPS equal to 30, higher than the NPS 28 deriving from the alternative indexing methods. The proposed multicriteria approach effectively considers case-specific environmental sustainability constraints, which result in determining 46% of the overall performance measure of the identified optimum solution. The results show that conventional single-objective methods underestimate the contribution of environmental factors up to 2.6% of the overall performance index value. A Monte Carlo probabilistic analysis is performed to verify the robustness of the results with respect to the possible uncertainties.

Phase-based design of CO2 capture, transport, and storage infrastructure via SimCCS3.0

The design of optimal infrastructure is essential for the deployment of commercial and large-scale carbon capture and storage (CCS) technology. During the design process, it is important to consider CO2 capture and storage locations and CO2 transportation pipelines to minimize the total project cost. SimCCS, first introduced in 2009, is an integrated open-source tool to optimize CCS infrastructure. The core CCS infrastructure design problem in SimCCS is structured as a mixed-integer linear programming problem by selecting the optimal pipeline routes, searching CO2 source capture and storage locations, and determining the corresponding CO2 amounts to meet desired capture targets. Multiple important and practical features have been developed to the latest version of SimCCS, SimCCS3.0. One of these features is phase-based modeling which enables users to dynamically design the CCS infrastructure. We demonstrate the phased-based modeling capability using two CCS infrastructure optimization case studies. The results from these case studies reveal that the phase-based modeling capability in SimCCS is particularly useful to optimize the dynamic deployment of CCS projects.

A Systematic Review of Carbon Capture, Utilization and Storage: Status, Progress and Challenges

The problem of global warming and climate change has attracted global attention, and reducing the concentration of CO2 in the atmosphere is an important step towards solving the problem. This paper mainly introduces the current development status, research hotspots, challenges and some emerging technologies of carbon capture, utilization and storage (CCUS). Among CO2 capture technologies, solvent absorption technology is currently the most mature and widely used technology, among which ionic liquid technology has great application prospects because its molecular structure can be designed and different functional groups can be connected. The surface functionalization of metal–organic frameworks in the adsorption method endows them with excellent CO2 adsorption capacity. In CO2 transportation, temperature and pressure must be considered in pipeline transportation, because they will affect the phase state of CO2 transportation. The impact of impurities on CO2 pipeline transportation is a challenge that affects pipeline design and transportation safety. In CO2 utilization, the key to enhanced oil recovery, gas recovery and displacement of coalbed methane is to increase the recovery rate and increase the storage capacity at the same time. Only by strengthening the research on the adsorption behavior between CO2 and CH4 and revealing the relevant mechanism can innovative technologies be developed. The chemical utilization of CO2 has formed many routes, but they all lack certain advantages. Most scholars are working on catalysts for CO2 conversion, especially copper-based catalysts that can convert CO2 into methanol. The conversion rate of CO2 can be effectively increased through doping or process improvement. The coupling of electrocatalytic technology and renewable energy is an important development direction in the future. In CO2 storage, geological storage is currently the most important method, especially in saline aquifers. There are currently critical issues concerning reservoir integrity and leakage potential that should be further investigated. CO2 leakage will cause serious environmental problems, and the common monitoring methods are reviewed and discussed in this paper. Finally, the research status, hotspots and cooperation networks of CCUS are summarized by using CiteSpace software in order to help the development of CCUS technology. In addition, through the review and analysis, it is found that CCUS is faced with challenges such as low capture efficiency, difficulties in transformation and utilization, high operating costs, lack of strong support policies, and lack of international cooperation, which restrict the further development of CCUS.