Key Takeaways & Executive Findings
- •• • Energy consumption per unit CO2 captured reduced by 30–40% via molten salt TES replacing steam extraction, directly addressing the dominant operational cost in amine-based CCUS. • • Overall carbon fixation efficiency increased by 15–20% through integration of microalgal secondary fixation, extending the carbon utilization chain beyond primary capture. • • Investment payback period shortened to less than five years, indicating economic viability for retrofitting existing CFPP CCUS projects without major capital overhaul. • • Algal sludge converted to biomass fuel for co-firing, closing the carbon loop and reducing waste disposal burden, enhancing circular economy credentials.
Abstract
Under the synergistic policy framework of carbon peaking, carbon neutrality, and the circular economy, existing carbon capture, utilization, and storage (CCUS) projects in coal-fired power plants (CFPPs) face significant challenges, including high regeneration energy demand, reliance on turbine steam extraction, limited carbon utilization pathways, poor economic viability, and difficulties in by-product management. This study proposes an integrated low-carbon retrofitting strategy that couples molten salt thermal energy storage (TES) and microalgal carbon fixation systems with existing CCUS facilities under minimal plant modification. A closed-loop carbon and energy utilization framework is established, integrating waste heat recovery, primary CO2 capture, secondary biological carbon fixation, and biomass fuel recycling. The system operates through a gradient synergistic mechanism: (i) recovered waste heat is stored in a molten-salt TES unit to provide regeneration energy, replacing conventional steam extraction; (ii) CO2 is initially captured by the CCUS process; (iii) residual CO2 is further utilized by microalgae for deep carbon fixation; and (iv) harvested algal sludge is converted into biomass fuel for co-firing within the power plant, completing the carbon recycling loop. The technical architecture, coupling mechanisms, scenario-specific implementation pathways, and operational risk control strategies are systematically evaluated. Results indicate that the integrated system can reduce energy consumption by approximately 30%–40% per unit of CO2 captured, increase overall carbon fixation efficiency by 15%–20%, and shorten the investment payback period to less than five years. The framework enables transformation of conventional coal-fired power plants from single-purpose energy producers into multifunctional circular systems integrating energy generation, carbon cycling, and resource recovery. Owing to technological maturity, adaptability to different plant capacities and geographical conditions, and a clear deployment roadmap, this solution provides a practical, replicable, and scalable pathway for low-carbon and circular transition.
1. Introduction
Coal-fired power plants (CFPPs) remain a cornerstone of China's energy mix, yet their decarbonization is hindered by the high energy penalty of carbon capture, utilization, and storage (CCUS). Conventional CCUS relies on steam extraction from the turbine to regenerate solvents, consuming 20–30% of plant output and undermining net efficiency. Furthermore, captured CO2 is often geologically stored or used in limited applications, leaving the carbon utilization chain short and the economic case weak. By-product management, such as spent solvents or captured sulfur species, adds further operational friction. These bottlenecks have stalled widespread CCUS deployment despite policy imperatives for carbon neutrality.
This study confronts these barriers by integrating molten salt thermal energy storage (TES) to recover waste heat and supply regeneration energy, eliminating the need for steam extraction. Simultaneously, microalgal cultivation is coupled to the CCUS system to fix residual CO2, converting it into biomass that can be processed into fuel for co-firing. This closed-loop design not only reduces energy consumption by 30–40% per unit CO2 captured but also enhances overall carbon fixation by 15–20%, while shortening payback to under five years. By leveraging mature components and requiring minimal plant modification, the proposed system offers a pragmatic, scalable pathway for retrofitting existing CFPPs, transforming them from single-purpose power generators into integrated energy-carbon-resource hubs.
Loading authentic research manuscript (Pages 1–5)...
GU Xuedian, DENG Jiakang, CHANG Haixing, Shih-Hsin HO, REN Nanqi (2026). Integration of Carbon Capture, Utilization and Storage with Molten Salt Thermal Energy Storage and Microalgal Carbon Fixation for Circular Development in the Thermal Power Sector. Journal of Environmental Engineering Technology. https://doi.org/10.13205/j.hjgc.202608002
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the specific energy penalty reduction achieved by replacing steam extraction with molten salt TES, and how does this affect overall plant efficiency?
The integrated system reduces energy consumption per unit CO2 captured by 30–40%. By recovering waste heat and storing it in molten salt, the need for turbine steam extraction is eliminated, thereby preserving more of the plant's thermal output for electricity generation. This directly improves net plant efficiency and lowers the operational cost of carbon capture.
How does microalgal carbon fixation integrate with the CCUS process, and what is the fate of the algal biomass?
Residual CO2 from the CCUS unit is fed to microalgae cultures, which fix it photosynthetically, achieving secondary deep carbon fixation. The harvested algal sludge is processed into a biomass fuel that is co-fired in the plant boiler, thus recycling carbon and providing a renewable energy input. This extends the carbon utilization chain and reduces waste.
What are the scalability constraints of this integrated system for different CFPP capacities and geographical conditions?
The system is designed for adaptability: molten salt TES and microalgal cultivation can be scaled to match plant CO2 output. Geographical factors such as sunlight availability and land area influence microalgal productivity, but the study indicates that the technology is mature enough to be deployed across a range of plant sizes and locations, with a clear roadmap from pilot to large-scale implementation.
What is the economic payback period, and what factors contribute to its feasibility?
The investment payback period is less than five years. This is achieved through reduced energy consumption (lower operating costs), revenue from biomass fuel co-firing (offsetting coal use), and potential carbon credits. The use of mature components and minimal plant modification reduces capital expenditure, enhancing economic viability.
What are the main operational risks, and how are they mitigated?
Potential risks include molten salt corrosion, microalgal culture contamination, and variability in biomass yield. The study emphasizes operational risk control strategies, such as using corrosion-resistant materials, maintaining optimal culture conditions, and integrating robust monitoring systems. The technological maturity of each component reduces these risks, and the modular design allows for isolated troubleshooting.
Related Chinese Research & Cross-Citations
Synergistic Regulation by Long- and Short-Chain Quorum Sensing Signaling Molecules Enhances Sulfamethoxazole Metabolism in Electroactive Biofilms within a Microbial Electrolysis Cell Coupled Anaerobic Digestion System
High-strength sulfamethoxazole (SMX) wastewater severely inhibits anaerobic microorganisms, reducing organic degradation and methane yield. This study investigated the effects of short-chain (C6-HSL) and long-chain (C12-HSL) N-acyl-homoserine lactone (AHL) signaling molecules, individually and in combination, on the construction, performance, and antibiotic resistance gene (ARG) profiles of anaerobic electroactive biofilms within a microbial electrolysis cell coupled anaerobic digestion (MEC-AD) system. Compared to the control (no AHLs), SMX removal efficiency increased by 9.26%, 7.44%, and 10.67% for C6-HSL (T1), C12-HSL (T2), and combined (T3) treatments, respectively. Methane production rates rose by 20.4%, 16.9%, and 23.1% for T1, T2, and T3, respectively. AHLs promoted extracellular polymeric substance secretion, enhancing electroactive microbe attachment to the anode. Microbial community analysis revealed increased diversity and modulated key functional genera. Notably, Georgenia abundance increased by 16.77% (T1) and 36.47% (T3) but decreased by 15.99% (T2). ARG analysis showed that single AHLs elevated intI1, sul1, and sul2 abundances, whereas combined AHLs (T3) exhibited a milder response, with sul2 abundance reduced by 4.92% relative to control. This suggests synergistic AHLs suppress ARG host proliferation. This study first demonstrates that combined short- and long-chain AHLs enhance electroactive biofilm formation, maintain microbial community stability, and modulate ARG dissemination risk, offering a quorum sensing-based strategy for antibiotic wastewater treatment and risk management.
Preparation of Solid-Phase Carbon Sources with Different Ratios and Their Carbon Release Properties
Low C/N ratios in wastewater treatment plant effluent necessitate external carbon sources for denitrification, but conventional liquid carbon sources are costly and unstable. This study prepared nine composite solid-phase carbon sources by combining PHBV with natural cellulose materials (straw, sawdust, corncob) at different mass ratios. Dynamic release experiments, DOC analysis, UV-Vis spectroscopy, and EEM fluorescence were employed to characterize carbon release. Results showed that increasing cellulose proportion in corncob-based sources led to release patterns opposite to those of straw- and sawdust-based sources. For straw and sawdust, higher cellulose ratios accelerated release rates, increased total release and duration, reduced aromaticity and molecular weight of released DOM, and promoted protein-like components (tryptophan, tyrosine), indicating enhanced bioavailability. Under identical ratios, corncob-based sources exhibited moderate total release, release durations exceeding 134 h, lower DOM aromaticity and molecular weight, and lower humic substance proportion, indicating superior bioavailability and engineering potential. Among the nine sources, JG5, MX5, and CC4 (PHBV:cellulose mass ratios of 4:5, 4:5, and 1:1, respectively) showed optimal comprehensive performance with low theoretical maximum release, long release periods, and high mass transfer coefficients. EEM-PARAFAC identified three DOM components (protein-like C1, C2; humic-like C3), with protein-like components dominating. This study validates the relationship between cellulose proportion and release kinetics and reveals synergistic regulation of DOM components, offering guidance for designing effective solid-phase carbon sources.
Enhancement of Anaerobic Digestion Operational Efficiency for Guar Gum Production Wastewater Using a Microaerobic-Biochar Coupled System
Guar gum production wastewater contains 1,2-propanediol, which in conventional anaerobic treatment causes propionate accumulation and microbial inhibition. Microaerobic conditions foster fermentative bacterial metabolism, enhancing organic substrate conversion, while biochar promotes anaerobic microbial aggregation and oxygen tolerance. This study treated actual guar gum wastewater using three configurations: blank control, anaerobic, and microaerobic-biochar (O2/BC) coupled systems. Under mesophilic conditions (37 °C), with micro-aeration at 0.2 mL/(g VS·d) and biochar dosage of 15 g/L, the O2/BC system achieved a COD removal efficiency of 90%, 10.6 percentage points higher than the anaerobic control. Effluent COD and propionate concentrations dropped to 3800 mg/L and 0.15 g/L, respectively, representing reductions of 49.6% and 98.4% versus the control. Biogas production was 1.64 times that of the control, with a maximum methane concentration of 77.2%. Fourier transform infrared spectroscopy (FT-IR) indicated increased abundance of –OH, –CH2–, and C–O functional groups on sludge surfaces, revealing biochar's adsorption enhancement. Scanning electron microscopy (SEM) showed dense microbial aggregates dominated by long bacilli, distinct from conventional anaerobic sludge. Microbial community analysis revealed increased abundance of Clostridium and Comamonas, modulating the propionate-to-acetate ratio and optimizing acidification efficiency, thereby promoting complex organic degradation. This study provides a novel technical pathway for biological treatment of alcohol-rich organic wastewater.
Occurrence Characteristics, Source Apportionment, and Ecological Risk Assessment of Pesticides in Plateau Lakes: A Case Study of Dianchi Lake
This study systematically investigated the occurrence, spatial distribution, sources, and ecological risks of 160 pesticides in Dianchi Lake, a typical plateau lake impacted by agricultural activities. A total of 37 pesticides were detected in the water, with total concentrations ranging from 64.2 to 1132.8 ng/L (average 610.0 ng/L). Fungicides, including boscalid (BOS), fluopicolide (FPC), and dimethomorph (DMM), were dominant, contributing up to 65.0% of the total concentration. Spatially, the southern lake region exhibited significantly higher concentrations (672.5 ng/L) than the north, attributed to intensive facility agriculture. Highly hydrophobic pesticides, such as penconazole (PEN), showed a tendency to enrich in bottom layers. Source apportionment identified inflowing rivers and wastewater treatment plant effluents as primary input sources, with average concentrations 7 and 9 times higher than lake water, respectively. Ecological risk assessment revealed that pesticides posed the highest risk to algae, followed by daphnia and fish. Prometryn (PMT) was identified as a high-risk factor for algae, while profenofos (PFF) and carbendazim (CBD) posed potential threats to higher trophic levels. These findings provide fundamental data and technical support for understanding pesticide pollution in plateau lake ecosystems.
Microbiome Mechanisms of Composite Carbon Sources for Enhancing Denitrification and Reducing N2O Emissions
Biological nitrogen removal in wastewater treatment plants (WWTPs) is often limited by insufficient influent carbon sources, necessitating external carbon addition to enhance denitrification. Conventional single carbon sources, such as sodium acetate, frequently fail to meet the metabolic demands of complex microbial communities, compromising nitrogen removal efficiency and stability. Composite carbon sources, by providing multiple electron donors, can improve metabolic cooperation among microorganisms, yet their underlying microbial mechanisms remain insufficiently understood. In this study, activated sludge from a municipal WWTP was used to investigate the microbial mechanisms of composite carbon sources during denitrification. Batch denitrification experiments were conducted in combination with metagenomic and metatranscriptomic analyses to systematically characterize microbial community structure and functional gene expression under different carbon source conditions. Results showed that, compared with sodium acetate as the single carbon source, the composite carbon source system (sodium acetate: sodium succinate: ethanol = 2:1:3) increased the denitrification rate from (6.822 ± 0.141) mg/(L·h) to (8.370 ± 0.186) mg/(L·h), representing a 22.7% improvement, while reducing N2O accumulation by approximately 55%. Metagenomic analysis revealed that Ottowia, Rubrivivax, Thauera, and Zoogloea were the dominant denitrifying genera. Metatranscriptomic results further demonstrated that the composite carbon sources significantly upregulated the transcription of key denitrification genes, with nirS, norB, and nosZ increasing by 37.8%, 27.4%, and 48.6%, respectively. In addition, the composite carbon sources promoted complementary carbon metabolic strategies among different microbial communities, enhancing electron donor supply and improving denitrification efficiency. These findings indicate that composite carbon sources synergistically enhance denitrification performance through regulation of functional gene transcription in complex microbial communities, providing a theoretical basis for carbon source optimization in WWTPs.
Key Environmental Behaviors and Pollution Control Strategies of Tire Wear Particles in Aquatic Environments
Tire wear particles (TWPs) are emerging pollutants and constitute the dominant type of microplastics (MPs) in urban stormwater runoff, accounting for up to 90% of MPs in some cases. They are characterized by small size, high mobility, complex composition, and significant toxicity. Current research on TWPs remains fragmented, lacking a comprehensive understanding of their environmental behaviors and pollution control in aquatic systems. This review systematically analyzes the enrichment and vectoring roles of TWPs for coexisting pollutants, and their environmental fate, including ecotoxicological impacts, detection methodologies, release of intrinsic additives, and aggregation and sedimentation behaviors. Drawing on insights from other microplastic studies, the paper explores control technologies across the pollution pathway—source, transport, and terminal treatment—and proposes feasible management strategies. Key findings indicate that TWPs can adsorb heavy metals and organic contaminants, with adsorption capacities influenced by aging processes. Their aggregation is governed by solution chemistry, with critical coagulation concentrations varying with ionic strength and pH. The release of additives such as zinc and benzothiazoles is significant, posing ecological risks. Future research should focus on real-water aggregation mechanisms, additive release under natural conditions, long-term performance of treatment facilities like constructed wetlands under TWPs stress, enzymatic degradation pathways, and integration of AI, big data, and IoT for cost-effective detection and risk modeling. This review provides a scientific basis for developing targeted pollution control measures for TWPs in aquatic environments.