Carbon Capture, Utilization, And Storage Research Articles

Toward a Green Energy System: How Does Carbon Capture, Utilization, and Storage Technology Innovation Promote Green Total Factor Productivity?

Abstract Using a panel data set from 2007 to 2019, we empirically evaluate the impact of carbon capture, utilization, and storage (CCUS) technology innovation on green total factor productivity (GTFP). The findings show that (1) CCUS technology innovation significantly improves GTFP. (2) CCUS technology innovation significantly contributes to GTFP by promoting industrial structure upgrading and carbon emissions efficiency. (3) Environmental regulation plays a positive moderating role in the nexus between CCUS technology innovation and GTFP. The findings of this paper provide guidance for China to achieve green energy transition and build a green energy system.

Comparative Evaluation of Carbon Capture, Utilization, and Storage (CCUS) Technologies Using Multi-Criteria Decision-Making Approaches

Comparative Evaluation of Carbon Capture, Utilization, and Storage (CCUS) Technologies Using Multi-Criteria Decision-Making Approaches

Generalized functionals for qualification of geological carbon storage injection sites

Many nations have pledged to reach carbon neutrality by 2050. Embarking on the decarbonization journey, they posited geological carbon storage (GCS) as a pivotal technology within the carbon capture, utilization, and storage (CCUS) framework. The CCUS chain operates to reduce “hard-to-abate” emissions at key sectors by capturing carbon dioxide (CO2), reusing it, transporting it, or disposing of it via injection into underground geological formations for permanent storage. Despite the global success of GCS ventures, mainly driven by the oil and gas industry, GCS initiatives are still in their early stages in several developing countries. In Brazil, for instance, a full setup covering precise storage capacity databases, potential CCUS clusters, national regulatory structure, and auxiliary computer-aided engineering is underway. Intended to push the frontier in the latter subject, this paper introduces mathematical models for qualifying underground CO2 storage sites. Our research explores a family of multivariate functionals endowed with underlying reservoir features and distinct weighting functions, thus envisioning two primary objectives. Firstly, it clarifies non-linear interactions between rock and fluid properties using quality indicators. Secondly, it evaluates geographical regions considering structural traps/caprocks settings. Backed by the Matlab Reservoir Simulation Toolbox (MRST) capabilities, the methodology is a subsidiary resource for identifying suitable injection and storage sites. A case study using the UNISIM-I-D model generated dozens of volumetric quality maps that point to unique potential storage sites. Numerical simulation experiments of injection comparing legacy and novel wells reveal storage surpluses improved by up to 50%. The paper seeks to establish foundational knowledge in GCS efficiency for general underground settings. One expects that these outcomes leverage well-repurposing perspectives and stimulate field appraisal actions to scale up GCS projects both in Brazil and worldwide.

Evolution of CO2 Storage Mechanisms in Low-Permeability Tight Sandstone Reservoirs

Understanding the storage mechanisms in CO2 flooding is crucial, as many carbon capture, utilization, and storage (CCUS) projects are related to enhanced oil recovery (EOR). CO2 storage in reservoirs across large timescales undergoes the two storage stages of oil displacement and well shut-in, which cover multiple replacement processes of injection–production synchronization, injection only with no production, and injection–production stoppage. Because the controlling mechanism of CO2 storage in different stages is unknown, the evolution of CO2 storage mechanisms over large timescales is not understood. A mathematical model for the evaluation of CO2 storage, including stratigraphic, residual, solubility, and mineral trapping in low-permeability tight sandstone reservoirs, was established using experimental and theoretical analyses. Based on a detailed geological model of the Huaziping oilfield, calibrated with reservoir permeability and fracture characteristic parameters obtained from well test results, a dynamic simulation of CO2 storage for the entire reservoir life cycle under two scenarios of continuous injection and water–gas alternation were considered. The results show that CO2 storage exhibits the significant stage characteristics of complete storage, dynamic storage, and stable storage. The CO2 storage capacity and storage rate under the continuous gas injection scenario (scenario 1) were 6.34 × 104 t and 61%, while those under the water–gas alternation scenario (scenario 2) were 4.62 × 104 t and 46%. The proportions of storage capacity under scenarios 1 and 2 for structural or stratigraphic, residual, solubility, and mineral trapping were 33.36%, 33.96%, 32.43%, and 0.25%; and 15.09%, 38.65%, 45.77%, and 0.49%, respectively. The evolution of the CO2 storage mechanism showed an overall trend: stratigraphic and residual trapping first increased and then decreased, whereas solubility trapping gradually decreased, and mineral trapping continuously increased. Based on these results, an evolution diagram of the CO2 storage mechanism of low-permeability tight sandstone reservoirs across large timescales was established.

Unleashing geological sequestration potential of mature oilfield by enforcing 4-dimensional seismic model-based inversion in Widuri Field, Indonesia

Implementing reservoir characterization by undertaking seismic inversion on time-lapse surveys is very effective for observing the distribution and changes in the hydrocarbon reservoir. In mature oilfields, these changes are most likely influenced by the thermodynamic activities including the injection of fluid into the reservoir, which can change the volume, pressure, and composition of the geological formations. Fluid injection (in this case, water injection) into the reservoir is typically used as an oil and gas booster to increase production through EOR (Enhanced Oil Recovery). However, in light of CCUS (Carbon Capture Utilization and Storage) application, injecting CO2 can be considered as a new EOR strategy development, with the dual objectives of increasing oil and gas production as well as lowering carbon emissions at the same time. The 4-dimensional (4D) seismic data available over Widuri Field covers an area of 125 km2, with 884 inlines and 905 crosslines, acquired in 1991 and 2004 over the same area. The inversion algorithm is using seismic deconvolution to generate an acoustic impedance model before developing a geological reservoir model. Reservoir characterization was conducted in this study to obtain detailed information of the reservoir zones by determining the impact of water injection that replaces hydrocarbons. Intervals and areas with an abundance of water can be considered as potential CO2 sequestration in the future, as a part of the CCUS application. In conclusion, the findings of increasing impedance from inversion data from 1991 to 2004 can indicate the presence of existing porosity and permeability. This evidence could indicate reservoir capability as CO2 storage.

CO2-responsive polymer promoted by polyether to efficient viscosity increase for CO2 plugging

A novel series of CO2-responsive polymers with unique hydrophobic structures were developed, capable of efficiently increasing viscosity in response to CO2 at low concentrations. These polymers, namely PAD-H, were synthesized by copolymerizing acrylamide, 2-(dimethylamino)ethyl methacrylate, and octadecyl polyoxyethylene ether methacrylate. In parallel, two comparative polymer sets were crafted, lacking the long polyether chains in their hydrophobic structures. DMAEMA imparts CO2-responsiveness through its tertiary amine groups, while the hydrophobic monomer contributes an alkyl structure with polyether long chains. These hydrophilic polyether long chains provide enhanced mobility to the hydrophobic alkyl chains, enabling lower concentration molecular hydrophobic association post CO2 exposure, thus leading to an increase in viscosity. This research delved into the mechanism of CO2-responsive viscosity increase, examining the impact of the polymer's intrinsic structure and external factors on its responsive behavior. Additionally, the polymer was applied in CO2 flooding, a crucial technique in carbon capture, utilization, and storage (CCUS). Simulated reservoir conditions were used to conduct in-situ CO2-responsive viscosity increase tests and CO2 gas channeling plugging experiments, substantially enhancing plugging efficiency. This advancement offers practical materials for addressing gas channeling in CO2 flooding and augments the technical methodologies for carbon utilization and storage within the CCUS framework.

India’s Transition Towards Becoming a Carbon Neutral Nation

The escalating impacts of climate change and the imperative to decarbonize global energy systems have spurred a concerted effort toward exploring and adopting renewable energy technologies. Among all these options, wind energy stands out as a top choice. It has a lot of potential to meet the growing need for energy and help the environment simultaneously. In this study, we comprehensively assess wind energy potential in five key cities across India: Udupi, Kollam, Surat, Visakhapatnam, and Jamnagar. Leveraging two decades of wind data sourced from reputable repositories such as the Iarc Power Project of NASA, we employ rigorous statistical analysis, including the application of the Weibull distribution, to elucidate the probability distribution of wind speeds and assess the viability of wind energy utilization in each city. We have also focused on other ways for decarbonizing India using new and advanced technologies such as Carbon Capture, Utilization and Storage (CCUS), and green hydrogen. Our analysis extends beyond theoretical considerations to encompass practical dimensions such as infrastructure requirements, cost implications, and technological advancements. Through meticulous evaluation, we aim to provide actionable insights that can inform policy formulation, infrastructure development, and investment strategies aimed at accelerating the adoption of wind energy technologies in India. Our research suggests a solution for implementing and policy framework for CCUS to make it more effective in achieving India’s carbon-neutral goals. We have also discussed green hydrogen its types, cost of implementation, and its current application. By fostering dialogue and collaboration, our research seeks to contribute to the ongoing discourse surrounding renewable energy transitions, facilitating informed decision-making towards a more sustainable energy future.

From carrot to stick – the impact of a changing landscape of CCS policy and funding in Australia since 1999

Since 1999 successive Australian Commonwealth governments have provided direct funding for carbon capture, utilisation and storage (CCUS) projects, notably the carbon capture and storage (CCS) Flagships Fund (Rudd government, 2009). The most recent CCUS Hubs and Technologies Fund (Morrison government, 2022) was later revoked (Albanese government, 2022) marking a shift from direct funding (‘carrot’) to emission reduction through a strengthening of the Safeguard Mechanism, the introduction of a 43% emissions reduction target by 2030, and the establishment of the Net Zero Authority (‘stick’). Reports such as the ‘Net Zero Mobilisation Report’, have delineated the need for, and size of, the role of CCUS in Australia, especially for hard-to-abate sectors and the report states ‘private investment in a CCUS industry requires targeted government support’ i.e. funding. As government focus moves from direct funding support for CCS to CCU and direct air capture (DAC), the development of underground geological storage of carbon dioxide will be largely left to fossil fuel emitters, especially large liquefied natural gas (LNG) companies, reflected in current Western Australian government policy (Cook government, 2023) to develop CCS strategy as part of the LNG Jobs Taskforce. The only current exception is CarbonNet, operated by the Victorian government and one of the early CCS Flagship funded projects.

Reliable local renewable power decarbonising offshore energy

Reliable local renewable power generation enables more environmentally and economically viable operations, to meet with the challenge of renewable energy intermittency and energy security. The Renewables for Subsea Power (RSP) project support targets towards Net Zero Targets by providing a full solution to generate low carbon, cost-effective, power and communications to remote locations in the offshore energy industry. The development of the RSP system is a collaborative project led by three UK-based companies in partnership with wider industry engagement from operators and the Aberdeen-based Net Zero Technology Centre. Carbon capture, utilisation and storage (CCUS) is set to play a key role in the energy transition. CCUS developments will incorporate all-electric subsea systems that can benefit from the RSP solution. This first of a kind integrated solution will contribute significantly to the generation of clean energy in the petroleum industry using a Wave Energy Converter and seabed battery energy storage for production control applications. The various applications that would benefit from the cost and CO2 savings from deploying the system, compared to traditional methods, include umbilical remediation, brownfield expansion, long offsets, CCUS, and Autonomous Underwater Vehicle residency. For CCUS projects key advantages are a specific design catered towards simplified controls architecture (e.g. electric controls), and the ability to offer an alternative to direct current fibre-optic from shore. A full system demonstrator deployment commenced in Feb-23 and has demonstrated system capability to power subsea equipment and an Autonomous Underwater Vehicle (AUV). Trials continue through 2024.

Commercialising carbon capture and storage – how much does regulatory certainty truly matter?

With carbon capture, utilisation and storage (CCUS) technology advancement reaching a point of scalability, there is a desperate need for global regulatory and legislative frameworks to support large-scale commercialisation. With various economies at differing stages of updating their policy and regulatory frameworks, the impact on investment into large-scale CCUS projects is an area worth interrogating to understand whether regulatory certainty has material impact on viability of a CCUS project, or whether the bulk of the project economics are still driven by traditional cost components. This paper seeks to undertake a literature review of current regulatory and policy frameworks such as the US Inflation Reduction Act 2022 and Australia’s Safeguard Mechanism to undertake a relative comparison of the two leading regulatory policies on large-scale carbon capture and storage. This paper will also undertake a comparison of a theoretical large-scale carbon capture and storage project subject to each type of regulatory condition to estimate the potential impact on project viability in each scenario. The aim of the paper is to understand the magnitude of impact that regulatory policies can have on commercialisation of a large-scale CCUS project.

Hydrogen and carbon capture utilisation and storage policy for progress on climate change mitigation

This paper highlights the need for Australia to enhance its climate change policies, arguing that the introduction of Contracts for Difference (CfD) policy mechanisms is an appropriate successor to Hydrogen Headstart and would support the development of hydrogen and carbon capture, utilisation and storage (CCUS) industries. CfDs are financial agreements designed to provide price certainty, support investment, and bridge the cost gap between new and established technologies. With explanation of different CfD structures and examples from other countries the paper argues that implementing CfDs could attract investors, provide confidence to the sector, and ultimately help Australia meet its climate change obligations.

Experimental study of leakage characteristics and risk prediction of N2-containing dense-phase CO2 pipelines in real transportation conditions

In the background of pipelines being widely used as a critical transportation chain for the carbon capture, utilization and storage (CCUS) process, studying the leak diffusion characteristics and risks of high-pressure impure CO2 pipelines in real transportation conditions is critical for process safety. Due to the limitations of the capture process and economic cost, the CO2 used for sequestration contains impurities in the range of 3% molar ratio, mainly N2. In this paper, the first leakage experiments involving dense-phase CO2 with a 3% molar ratio of N2 impurity were conducted on a large CO2 pipeline (258 m long and 233 mm inner diameter) using initial leakage orifices of 50 mm and 100 mm. Data concerning the thermodynamic properties of the impurity-containing leakage source were gathered for the analysis of phase transitions and flow alterations within the pipeline, as well as near-field temperature and the progression of the far-field concentration. The pressure-temperature curve in the pipe shifted along the dew line and then slowly shifted to the saturation line of pure CO2 with the influence of N2 impurities during the multiphase leakage phase. In the near-field region, cryogenic diffusion was governed by the boundary of the jet, with the control distance decreasing as the leakage orifice increased. In addition, an accurate prediction model of CO2 concentration on the leak axis was established based on the virtual source theory and the concentration decay law, and the predicted locations of CO2 concentrations at the 5% were 169 m and 210 m. As the leak orifice increases, the risk of low temperatures and high concentrations escalates, albeit with a sharp decrease in duration. These data provide accurate leakage characteristics and risk assessment for safely operating high-pressure CO2 processes under real conditions with impurities.

Benedict–Webb–Rubin–Starling Equation of State + Hydrate Thermodynamic Theories: An Enhanced Prediction Method for CO2 Solubility and CO2 Hydrate Phase Equilibrium in Pure Water/NaCl Aqueous Solution System

Accurately predicting the phase behavior and physical properties of carbon dioxide (CO2) in pure water/NaCl mixtures is crucial for the design and implementation of carbon capture, utilization, and storage (CCUS) technology. However, the prediction task is complicated by CO2 liquefaction, CO2 hydrate formation, multicomponent and multiphase coexistence, etc. In this study, an improved method that combines Benedict–Webb–Rubin–Starling equation of state (BWRS EOS) + hydrate thermodynamic theories was proposed to predict CO2 solubility and phase equilibrium conditions for a mixed system across various temperature and pressure conditions. By modifying the interaction coefficients in BWRS EOS and the Van der Waals–Platteeuw model, this new method is applicable to complex systems containing two liquid phases and a CO2 hydrate phase, and its high prediction accuracy was verified through a comparative evaluation with a large number of reported experimental data. Furthermore, based on the calculation results, the characteristics of CO2 solubility and the variation of phase equilibrium conditions of the mixture system were discussed. These findings highlight the influence of hydrates and NaCl on CO2 solubility characteristics and clearly demonstrate the hindrance of NaCl to the formation of CO2 hydrates. This study provides valuable insights and fundamental data for designing and implementing CCUS technology that contribute to addressing global climate change and environmental challenges.

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.

Research on carbon dioxide capture materials used for carbon dioxide capture, utilization, and storage technology: a review.

In recent years, climate change has increasingly become one of the major challenges facing mankind today, seriously threatening the survival and sustainable development of mankind. Dramatically increasing carbon dioxide concentrations are thought to cause a severe greenhouse effect, leading to severe and sustained global warming, associated climate instability and unwelcome natural disasters, melting glaciers and extreme weather patterns. The treatment of flue gas from thermal power plants uses carbon capture, utilization, and storage (CCUS) technology, one of the most promising current methods to accomplish significant CO2 emission reduction. In order to implement the technological and financial system of CO2 capture, which is the key technology of CCUS technology and accounts for 70-80% of the overall cost of CCUS technology, it is crucial to create more effective adsorbents. Nowadays, with the development and application of various carbon dioxide capture materials, it is necessary to review and summarize carbon dioxide capture materials in time. In this paper, the main technologies of CO2 capture are reviewed, with emphasis on the latest research status of CO2 capture materials, such as amines, zeolites, alkali metals, as well as emerging MOFs and carbon nanomaterials. More and more research on CO2 capture materials has used a variety of improved methods, which have achieved high CO2 capture performance. For example, doping of layered double hydroxides (LDH) with metal atoms significantly increases the active site on the surface of the material, which has a significant impact on improving the CO2 capture capacity and performance stability of LDH. Although many carbon capture materials have been developed, high cost and low technology scale remain major obstacles to CO2 capture. Future research should focus on designing low-cost, high-availability carbon capture materials.

Optimum operation condition of fluidized-bed homogeneous crystallization technology for the recovery of carbon dioxide captured in flue gas

The decarbonization of industry, particularly in "hard-to-decarbonize" sectors like combustion plants, poses a significant challenge due to the limited availability of low-carbon options. Carbon capture, utilization, and storage (CCUS) offers a promising solution to this challenge. Chemical precipitation is one method of converting CO2 into precipitated mineral carbonates, which can be stored and converted into valuable materials. This study explores fluidized-bed homogeneous crystallization (FBHC) technology for recovering carbonate from simulated CO2-enriched flue gas, resulting in stable calcium carbonate granules. Factors such as pH, carbonate concentration, reactor type, and reactants significantly impact carbonate removal and crystallization efficiency. Optimal conditions were found at 0.086 M input carbonate concentration, pH 9.0, and using a two-stage reactor, achieving 99.9 % removal and 93.2 % crystallization efficiency. Potassium-based absorbents yield higher crystalline intensity and larger granules compared to sodium. X-ray diffractometry confirms the composition of calcium carbonates, demonstrating FBHC's effectiveness for CO2 capture and storage. Utilizing calcium carbonate granules for carbon dioxide sequestration can potentially reduce emissions, pending resolution of investment and feasibility challenges.

Deriving a Framework of Science and Technology Cooperation for Responding to Climate Change with Developed Countries: The Case of the ROK-UK Cooperation

Climate technology is one of the most crucial factors of mitigating greenhouse gas emission and attaining carbon neutrality. The Republic of Korea (ROK) and the United Kingdom (UK) have strengthened science and technology cooperation while climate technology has not been actively discussed so far. This study aimed to suggest a preliminary framework of cooperation on climate technology by analyzing national strategies and official cooperation activities. The national strategies and plans in terms of climate technologies were analyzed to derive common technological interest of the ROK and the UK. Technologies in sectors of energy conversion, building, transportation, agriculture·livestock·fishery, hydrogen, carbon sink, and carbon capture, utilization and storage (CCUS) were identified. Network establishment and joint research and development (R&D) program were defined as main modalities of bilateral cooperation, according to a quantitative analysis on official announcement of the ROK on the cooperations. The methodology of this study is expected to be efficient and relevant as the official and public information·data had been utilized to identify common technological interests and to derive modality of cooperation. We hope this preliminary framework of cooperation on climate technology can contribute to facilitating and mainstreaming bilateral climate technology cooperation.

Lifecycle carbon footprints of buildings and sustainability pathways in China

The Paris Agreement, with a 2 °C temperature increase baseline and a 1.5 °C target temperature increase, imposes challenges to the sustainability of buildings. However, as an end-user or end-of-the-art, the building sector overlaps with other sectors, such as industry and transportation in building materials manufacturing (such as steel, concrete, cement, etc. ) and electricity use (such as building-to-vehicle charging), imposing difficulties in lifecycle carbon footprint quantification in buildings. In this study, the lifecycle carbon footprint of buildings and sustainability pathways in China are provided. Tools and platforms for lifecycle carbon footprint quantification in buildings are reviewed. A global database for lifecycle carbon footprint quantification in buildings is reviewed and compared, together with an analysis of the advantages and disadvantages. Furthermore, decarbonization technologies in the building operation stage are comprehensively reviewed, including the decarbonization potential, technology readiness level (TRL), techno-economic performance, and current technical status. Pathways on carbon neutrality in building sectors in China are provided. The results indicate that inconsistencies in global databases, unclear definitions of lifecycle carbon emissions, and inaccurate models of building energy consumption are the main challenges for accurate lifecycle carbon analysis in buildings. Various carbon neutrality transformation technologies can be classified into ultralow energy building and near zero-energy building technologies and into efficient heat pump and smart metering technologies. Pathways for low-carbon transition in building sectors include building energy saving (330 million tCO2 with 22%), renewable energy supply (299 million tCO2 with 20%), building electrification and power sector decarbonization (450 million tCO2 with 30%), and carbon capture, utilization and storage (CCUS) technology (420 million tCO2 with 28%). These research results can pave the way for upcoming studies on the lifecycle carbon footprint in buildings and sustainability pathways in China.

Efficient Absorption of CO2 by Protic-Ionic-Liquid Based Deep Eutectic Solvents.

Carbon capture, utilization, and storage (CCUS) are among the key technologies to achieve large-scale carbon emission reduction globally. Deep eutectic solvents (DESs) are considered as designable solvents, which has attracted intensive attention for CO2 capture. Here, a series of binary DESs are synthesized through one-step mixing with the starting materials of protic ionic liquid (PIL) and amine. The eutectic behavior was investigated by measuring the melting point of PILs and amine. The saturated vapor of these DESs and industrial MDEA solution were measured and compared. These DESs are investigated to have high absorption capacity (0.1 g ⋅ g-1 at 1.0 bar and 25 °C), superior apparent absorption rate constant (0.381 min-1 vs 0.012 min-1 of 70 wt.% MDEA), moderate interaction with CO2 (the enthalpy change is as low as -34.8 kJ ⋅ mol-1). The absorption mechanism is also investigated by NMR analysis. Eight absorption/desorption regeneration experiments are carried out to show their reversibility. Considering the advantages, including convenience of synthesis, large absorption capacity, fast absorption rate, and moderate interaction energy as well as good regeneration, these DESs are believed to be as potential CO2 absorbent in practical applications.

High-efficiency thermal reduction of CO2 to high-valued carbon nanotubes

To reduce the amount of carbon dioxide (CO2) already emitted into the atmosphere, various carbon capture, utilization, and storage (CCUS) technologies have been developed for climate and economic reasons in recent years. However, the state of art CCUS techniques suffer from deficiencies such as high cost, low yield, and harsh and discontinuous production conditions. In this work, we report a new thermal reduction method for continuously conversing CO2 to methane (CH4) by introducing sodium borohydride (NaBH4) as a reductant under catalyst-free conditions. Experimental results show that CO2 can be fully captured and converted to CH4 and carbon monoxide (CO) and the selectivity efficiency of CO2 to CH4 can be achieved to be as high as 90% with the optimization of experimental conditions. Such a result originates from the high activity of NaBH4 and high selectivity of the thermal reduction of CO2. To demonstrate one of the potential usages of the reduction products, we integrated the thermal reduction of CO2 with the production of carbon nanotubes (CNTs). As long as CO2 is supplied at the source end, the reduction products can undergo catalytic decomposition to produce a CNT fiber or film continuously at the final end. The present technique is featured with simple equipment setup, low cost, and continuous thermal reduction, thus providing a new pathway for the large-scale conversion of CO2 into high-valued products for wide applications.