CO₂ Capture and Renewable Energy, 2nd Edition

Topic Information

Dear Colleagues,

The following Topic is a continuation of the previous successful Topic “CO₂ Capture and Renewable Energy”. (https://www.mdpi.com/topics/CO2_capture_renewable_energy) The rapid and global development of an energy sector based on renewables and green sources is critical for the decarbonization of energy in a climate-friendly scenario. However, CO₂ capture, utilization, and storage (CCUS) continues to play a vital role in mitigating CO₂ emissions from industrial sources that are challenging or impossible to fully decarbonize. Complementing this, CO₂ removal technologies, including bioenergy with carbon capture and storage (BECCS), direct air capture (DAC), CO₂ mineralization, and photosynthetic CO₂ uptake by microalgae, will be indispensable in achieving negative emissions and addressing the rising atmospheric concentration of CO₂. This topic aims to emphasize not only the current status and advancements in CO₂ capture technologies and renewable energy systems but also their integration into sustainable solutions for a low-carbon future. A particular focus will be placed on the molecular-level understanding of CO₂ capture and transformation processes, including the design of novel materials, catalysts, and chemical pathways that improve efficiency and reduce environmental impact. Additionally, this issue will explore the lifecycle sustainability of these technologies, highlighting innovative approaches to enhance the scalability and affordability of CCUS and CO₂ removal techniques.

Dr. Haris Ishaq
Dr. Cheng Cao
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Clean Technologies cleantechnol	5.9	9.4	2019	20.9 Days	CHF 1800
Energies energies	3.9	8.3	2008	16.7 Days	CHF 2600
Molecules molecules	5.1	10.3	1996	15.6 Days	CHF 2700
Processes processes	3.4	5.7	2013	14.7 Days	CHF 2400
Sustainability sustainability	4.1	8.9	2009	16.9 Days	CHF 2400

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Published Papers (6 papers)

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24 pages, 6286 KB  

Open AccessArticle

The Leaching Performance and Mechanism of Calcium Ions from Coal Fly Ash Under Sequential Alkaline-Acid Processing

by Xiaohu Yang, Yonghui Wu, Kui Sun, Liqiang Ma, Jie Peng, Shuyue He, Shicheng Li and Shiqi Chen

Processes 2026, 14(11), 1731; https://doi.org/10.3390/pr14111731 - 26 May 2026

Viewed by 265

Abstract

Liquid-phase mineralization of CO₂ using coal fly ash (CFA) is an efficient approach to permanent CO₂ sequestration. To address the low leaching efficiency of calcium ions (Ca²⁺) in carbon mineralization, this study systematically investigates the leaching performance and leaching [...] Read more.

Liquid-phase mineralization of CO₂ using coal fly ash (CFA) is an efficient approach to permanent CO₂ sequestration. To address the low leaching efficiency of calcium ions (Ca²⁺) in carbon mineralization, this study systematically investigates the leaching performance and leaching mechanism of calcium ions from CFA by using a sequential alkaline-acid processing (i.e., alkaline activation followed by acid leaching). The effects of NaOH concentration, acid concentration, acid type (HCl/CH₃COOH), reaction time, and grinding duration on leaching efficiency are studied. The reaction products are characterized by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). A kinetic model is proposed to analyze the reaction dynamics and leaching mechanisms. The results show that the maximum Ca²⁺ leaching efficiency for untreated CFA is 43.7% after 40-min acid leaching with 7 mol/L HCl and 1:1.5 S/L ratio. The leaching efficiency can be enhanced to 72.1% after 50-min alkaline activation with 11 mol/L NaOH. Grinding the CFA can further increase the leaching performance of Ca²⁺. It is shown that the leaching efficiency can be enhanced to 58.75% and 82.3% after 90-min grinding, respectively, for cases without and with 50-min alkaline activation using 9 mol/L NaOH. It is also shown that a peak leaching efficiency of 86.51% can be obtained when 8 mol/L CH₃COOH is used for the acid system. The mechanism for the enhancement of leaching efficiency is that both NaOH activation and mechanical grinding can break down the calcium and aluminum silicate vitreous matrix of CFA, facilitating calcium release. Ca²⁺ leaching performance exhibits two regimes. The leaching efficiency is significantly time-dependent in the first regime, and it remains almost constant in the second regime after the efficiency reaches a pseudo-maximum value. The contribution of this study is that a theoretical foundation is provided for enhancing the Ca²⁺ recovery from CFA, which makes it practical for large-scale CFA utilization and permanent CO₂ sequestration in industry applications. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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17 pages, 1540 KB  

Open AccessArticle

Gas Injection Optimization and Shrinkage Control for Salt Cavern CO₂ Storage (SCCS) Based on Creep-Shrinkage Sensitivity Analysis

by Tingting Jiang, Yiyun Zhang, Youqiang Liao, Dongzhou Xie and Tao He

Energies 2026, 19(8), 1970; https://doi.org/10.3390/en19081970 - 18 Apr 2026

Viewed by 353

Abstract

Salt cavern CO₂ storage (SCCS) technology represents a crucial pathway for achieving large-scale carbon sequestration. However, its long-term operation faces the challenge of cavern shrinkage due to surrounding rock creep, which directly impacts storage safety and stability. Despite its importance, there is [...] Read more.

Salt cavern CO₂ storage (SCCS) technology represents a crucial pathway for achieving large-scale carbon sequestration. However, its long-term operation faces the challenge of cavern shrinkage due to surrounding rock creep, which directly impacts storage safety and stability. Despite its importance, there is currently a lack of research focusing on the proactive control of SCCS cavern shrinkage and its collaborative optimization with operational economy. To fill this gap, this paper first investigated the effects of the stress state (f₁), height-to-diameter ratio (f₂), symmetry factor (f₃), and cavern volume (f₄) on the volumetric shrinkage rate through numerical simulations of regular caverns and univariate sensitivity analysis. The sensitivity ranking and quantitative relationships of these factors were clarified as $f_1(2.31)>f_4(0.309)>f_2(0.166)>f_3(0)$. Subsequently, a multi-objective nonlinear optimization model was established, and the primal-dual interior-point method was adopted as the solution algorithm. Using actual cavern data as a case study for the solution, the results demonstrate that the optimization model converges stably in approximately 1.1 s. The resulting optimal gas injection allocation scheme achieves a 14.77% improvement in the comprehensive score compared to the baseline scheme. This study provides a theoretical basis and a practical tool for the rapid generation of SCCS gas injection allocation schemes. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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19 pages, 9944 KB  

Open AccessArticle

Molecular Simulation Study of Water–Rock Interfaces During Supercritical CO₂ Sequestration

by Yuanzi Yan, Yunfeng Fan and Peng Zhang

Molecules 2026, 31(2), 268; https://doi.org/10.3390/molecules31020268 - 13 Jan 2026

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Abstract

Understanding how supercritical CO₂ and water interact with mineral surfaces is essential for predicting the stability and sealing performance of geological storage formations. Yet, the combined effects of mineral surface chemistry and confined pore geometry on interfacial structure and fluid dynamics remain [...] Read more.

Understanding how supercritical CO₂ and water interact with mineral surfaces is essential for predicting the stability and sealing performance of geological storage formations. Yet, the combined effects of mineral surface chemistry and confined pore geometry on interfacial structure and fluid dynamics remain insufficiently resolved at the molecular scale. In this study, molecular dynamics simulations were employed to quantify how methylated SiO₂, hydroxylated SiO₂, and kaolinite regulate CO₂–H₂O interfacial behavior through variations in wettability and electrostatic interactions. The results show a clear hierarchy in water affinity across the three minerals. On methylated SiO₂, the water cluster remains spherical and poorly anchored, with a contact angle of ~140°, consistent with the weakest water–surface Coulomb attractions (only −400 to −1400 kJ/mol). Hydroxylated SiO₂ significantly enhances hydration, forming a cylindrical water layer with a reduced contact angle of ~61.3° and strong surface–water electrostatic binding (~−18,000 to −20,000 kJ/mol). Kaolinite exhibits the highest hydrophilicity, where water forms a continuous bridge between the two walls and the contact angle further decreases to ~24.5°, supported by the strongest mineral–water electrostatic interactions (−23,000 to −25,000 kJ/mol). Meanwhile, CO₂–water attractions remain moderate (typically −2800 to −3500 kJ/mol) but are sufficient to influence CO₂ distribution within the confined domain. These findings collectively reveal that surface functionalization and mineral type govern interfacial morphology, fluid confinement, and electrostatic stabilization in the sequence methylated SiO₂ < hydroxylated SiO₂ < kaolinite. This molecular-level understanding provides mechanistic insight into how mineral wettability controls CO₂ trapping, fluid segregation, and pore-scale sealing behavior in subsurface carbon-storage environments. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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38 pages, 40159 KB  

Open AccessArticle

Hybrid-Energy-Powered Electrochemical Ocean Alkalinity Enhancement Model: Plant Operation, Cost, and Profitability

by James Salvador Niffenegger, Kaitlin Brunik, Katie Peterson, Andrew Simms, Tristen Myers Stewart, Jessica Cross and Michael Lawson

Clean Technol. 2026, 8(1), 12; https://doi.org/10.3390/cleantechnol8010012 - 9 Jan 2026

Cited by 1 | Viewed by 1980

Abstract

Electrochemical ocean alkalinity enhancement is a form of marine carbon dioxide removal, a rapidly growing industry that is powered by efficient onshore or offshore energy sources. As more and larger deployments are being planned, it is important to consider how variable energy sources [...] Read more.

Electrochemical ocean alkalinity enhancement is a form of marine carbon dioxide removal, a rapidly growing industry that is powered by efficient onshore or offshore energy sources. As more and larger deployments are being planned, it is important to consider how variable energy sources like tidal energy can impact plant performance and costs. An open-source Python-based generalizable model for electrodialysis-based ocean alkalinity enhancement has been developed that can capture key system-level insights of the electrochemistry, ocean chemistry, acid disposal, and co-product creation of these plants under various conditions. The model additionally accounts for hybrid energy system performance profiles and costs via the National Laboratory of the Rockies’ H2Integrate tool. The model was used to analyze an example theoretical plant deployment in North Admiralty Inlet, including how the plant is impacted by the available energy sources in the region and the scale at which plant costs are covered by the co-products it generates, such as recycled concrete aggregates, without requiring carbon credits. The results show that the example plant could be profitable without carbon credits at commercial scales of 100,000 to 1 million tons of carbon dioxide removal per year, so long as it uses low-cost electricity sources and either sells acid or recovers recycled concrete aggregates with about 1 molar acid concentrations, though more research is needed to confirm these results. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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14 pages, 1491 KB  

Open AccessArticle

Renewable Energy Transition and Sustainable Economic Growth in South Asia: Insights from the CO₂ Emissions Policy Threshold

by Mustapha Mukhtar, Idris Abdullahi Abdulqadir and Hassan Sani Abubakar

Sustainability 2025, 17(20), 9289; https://doi.org/10.3390/su17209289 - 19 Oct 2025

Cited by 2 | Viewed by 3609

Abstract

This article examines the asymmetric effects of renewable energy on sustainable economic growth across six South Asian countries from 2000 to 2023, employing panel data and threshold regression analysis. The findings indicate that CO₂ emissions must remain below a threshold of 2.38% [...] Read more.

This article examines the asymmetric effects of renewable energy on sustainable economic growth across six South Asian countries from 2000 to 2023, employing panel data and threshold regression analysis. The findings indicate that CO₂ emissions must remain below a threshold of 2.38% to support the integration of renewable energy with sustainable growth. Furthermore, access to clean energy and technologies should exceed 3.38%, and urbanization must be managed at a complementary threshold of 3.21%. These results are consistent with various studies investigating the renewable energy transition’s economic impacts globally. It is recommended that South Asia focus on reducing CO₂ emissions below the identified threshold, enhancing clean energy access and innovation above the designated thresholds, and supporting urban growth as part of its policy initiatives. Such actions are essential for fostering economic growth and ensuring the sustainability of the region. The study recommends that the South Asian region take decisive steps to reduce CO₂ emissions and enhance access to clean energy while accommodating urban population growth. It highlights the importance of transitioning to renewable energy to stimulate economic growth and maintain trade and foreign direct investment (FDI) as a viable part of the gross domestic product. The study suggests that investments in Gross Capital Formation (GCF), trade, and FDI will yield long-term benefits, although short-term policy adjustments may disrupt resource allocation and hinder economic and renewable energy development. Future research should explore the complex interactions between CO₂ emissions, clean energy access, FDI, and trade, particularly in light of recent trade policies, including U.S. tariffs. Investigating these relationships through advanced methodologies, such as machine learning, could provide valuable insights into drivers of renewable energy transition and economic outcomes. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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37 pages, 11435 KB  

Open AccessArticle

Hybrid Energy-Powered Electrochemical Direct Ocean Capture Model

by James Salvador Niffenegger, Kaitlin Brunik, Todd Deutsch, Michael Lawson and Robert Thresher

Clean Technol. 2025, 7(3), 52; https://doi.org/10.3390/cleantechnol7030052 - 23 Jun 2025

Cited by 2 | Viewed by 2446

Abstract

Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require [...] Read more.

Offshore synthetic fuel production and marine carbon dioxide removal can be enabled by direct ocean capture, which extracts carbon dioxide from the ocean that then can be used as a feedstock for fuel production or sequestered underground. To maximize carbon capture, plants require a variety of low-carbon energy sources to operate, such as variable renewable energy. However, the impacts of variable power on direct ocean capture have not yet been thoroughly investigated. To facilitate future deployments, a generalizable model for electrodialysis-based direct ocean capture plants is created to evaluate plant performance and electricity costs under intermittent power availability. This open-source Python-based model captures key aspects of the electrochemistry, ocean chemistry, post-processing, and operation scenarios under various conditions. To incorporate realistic energy supply dynamics and cost estimates, the model is coupled with the National Renewable Energy Laboratory’s H2Integrate tool, which simulates hybrid energy system performance profiles and costs. This integrated framework is designed to provide system-level insights while maintaining computational efficiency and flexibility for scenario exploration. Initial evaluations show similar results to those predicted by the industry, and demonstrate how a given plant could function with variable power in different deployment locations, such as with wind energy off the coast of Texas and with wind and wave energy off the coast of Oregon. The results suggest that electrochemical systems with greater tolerances for power variability and low minimum power requirements may offer operational advantages in variable-energy contexts. However, further research is needed to quantify these benefits and evaluate their implications across different deployment scenarios. Full article

(This article belongs to the Topic CO₂ Capture and Renewable Energy, 2nd Edition)

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