Solar-driven gasification of biomass under CO2 atmosphere offers an efficient method to utilize CO2 as gasification agent and store greater concentrated solar energy in syngas with potential better performance. In this study, an experimental analysis of solar CO2 gasification of pinewood is carried out in a designed indirectly combined drop-tube and fixed-bed solar reactor under high-flux solar simulator conditions. The influences of key parameters on the gasification performance are first obtained with different CO2/biomass molar ratio (0.3-0.6), biomass pellets feeding rate (1.2-1.6 g/min), purge gas flow-rate (1.5-2.0 NL/min), and gasification temperature (900-1100 degrees C). As a result, when the values of the CO2/biomass molar ratio, the biomass feeding rate, the purge gas flow-rate and the gasification temperature are adopted as 0.5 (slightly excess of CO2), 1.5 g/min, 1.5 NL/min and 1100 degrees C, the maximum syngas yield is obtained as 93.32 mmol/min, and the highest carbon conversion and energy upgrade factor are achieved as 85.80 % and 1.25. Additionally, increasing the temperature of the pyrolysis zone can improve the carbon conversion ratio by 21 % under the same condition. Subsequently, comparative analysis reveals that CO2 gasification outperforms steam gasification and inert-atmosphere pyrolysis in terms of syngas heating value, energy upgrade factor, and the solar-to-fuel efficiency, highlighting its potential for solar and biomass hybrid conversion systems.

Advancing efficient and durable green hydrogen production requires precise diagnosis of proton exchange membrane water electrolyzer (PEMWE) performance. This study introduces an innovative, integrated analytical framework that synergizes galvanostatic electrochemical impedance spectroscopy with distribution of relaxation times and equivalent circuit models (GEIS-DRT-ECM). This approach overcomes the empirical limitations of conventional methods, enabling the systematic deconvolution and quantification of key polarization processes under diverse operating conditions. Through DRT-based analysis, five distinct polarization processes were identified from the EIS spectra: proton transport impedance at the anode and cathode (P1, P2), charge transfer impedance at the cathode and anode (P3, P4), and mass transport impedance (P5). Additionally, variations in operating parameters significantly affect both the number and intensity of characteristic peaks. Furthermore, a novel ECM was developed to accurately decode the low-frequency inductive response, allowing the assessment of metal cation contamination and its impact on PEMWE degradation. Collectively, the robust diagnostic platform is critical for optimizing PEMWE operation compatible with intermittent renewable energy sources and for accelerating the development of advanced, cost-effective green hydrogen technologies.

With the large-scale development of renewable energy, coal-fired combined heat and power units face limited peak-regulation capability and reduced spot-market profitability due to inherent heat-power coupling characteristics. To enhance operational flexibility and economic performance, a molten salt-coupled steam accumulator system is proposed to enable full steam energy storage through coordinated utilization of sensible and latent heat. A steady-state thermodynamic model, an economic evaluation framework, and an uncertainty analysis model are developed to assess thermodynamic performance, economic feasibility, and robustness under spot-market operation. Results indicate that, under ideal insulation assumptions, complete storage of both the sensible and latent heat of steam can be achieved, with an ideal thermodynamic energy efficiency of 99.5%, significantly expanding the electrical load range in both heating and non-heating seasons. The integration of the molten salt-coupled steam accumulator system increases annual power-generation revenue by 1.18 million USD, reduces generation cost by 3.2 million USD, and provides an additional 0.56 million USD in capacity-related benefits. Financial evaluation yields a net present value of 11.7 million USD, an internal rate of return of 10.3%, and an equity internal rate of return of 26.5%, demonstrating economic feasibility. Sensitivity analysis identifies variable generation cost and equipment investment as dominant influencing factors, with net present value being most sensitive to the discount rate. The proposed molten salt-coupled steam accumulator framework, therefore, enhances the operational flexibility and spot-market profitability of coal-fired combined heat and power units and provides a generalizable approach for integrating full-energy thermal storage into combined heat and power plants.

The development of highly efficient oxygen evolution reaction (OER) electrocatalysts is essential for the sustainable production of clean hydrogen energy via proton-exchange membrane (PEM) water electrolysis. Ruthenium (Ru)-based catalysts are promising cost-effective alternatives to iridium (Ir)-based catalysts for acidic OER, yet the trade-off between activity and stability hinders their further optimization. Here, we report a metal-organic framework (MOF) precursor-mediated strategy to synthesize the Ru/RuMnMoO2 heterostructure catalyst. X-ray absorption fine structure, electrochemical evaluation, and theoretical calculation results demonstrated that doped Mn stabilized the lattice oxygen, while Mo promoted electron transfer to Ru, thereby suppressing the peroxide-induced Ru leaching. As expected, the Ru/RuMnMoO2 requires only 163 mV of overpotential to achieve 10 mA cmgeo-2 in acidic electrolyte and maintains long-term stability over 3000 h. Cation probe tests and density functional theory (DFT) calculations confirmed that Ru/RuMnMoO2 followed an adsorbate evolution mechanism (AEM). Notably, a PEM electrolyzer using Ru/RuMnMoO2 as the anode can deliver an ampere-level current density of 1.0 A cmgeo-2 at 1.70 V with a low Ru loading (0.59 mgRu cm-2), outperforming the commercial RuO2-based PEM electrolyzer (2.31 V@ 1.14 mgRu cm-2). Moreover, the cell can stably run for 240 h at a high current density of 3 A cmgeo-2, demonstrating its significant practical potential for alleviating the dependence on iridium.

Increasing penetration of renewable power requires greater operational flexibility from coal-fired units, and molten salt thermal storage is an effective option for improving such flexibility. In these systems, the molten salt steam generator acts as a key interface for converting stored thermal energy into deliverable steam. However, existing studies have mainly focused on steady-state performance and dynamic simulation, while direct experimental evidence under variable-load conditions remains limited. This study establishes a horizontal kettle-type molten salt steam generation experimental platform and conducts steady-state and variable-load experiments to investigate the thermohydraulic behavior of the steam generator. The results show that, as the load decreases from 100% to 40%, the overall heat-transfer coefficient continuously declines while the logarithmic mean temperature difference increases significantly, indicating that the deterioration cannot be explained by tube-side flow reduction alone. Comparisons with theoretical reference baseline and reference correlations further suggest that shell-side boiling progressively departs from the behavior expected for effective nucleate boiling under low-heat-flux conditions. Dynamic tests show a marked increase in response time in the 70%–80% load range, with low-load response times about 2–3 times those in the high-load region. Clear path-dependent thermal states are also observed, especially at 80%–100% load, where the molten salt outlet temperature differs markedly among operating paths at the same load. These findings indicate that low-load deterioration and dynamic behavior are closely associated with shell-side boiling-state variation and history dependence, providing experimental support for controlling molten salt steam generation systems in flexible thermal energy storage applications.

Developing Desert-Gobi-Wasteland (DGW) energy bases is critical for scaling up renewable energy deployment and advancing the global energy structure transition. However, the inherent intermittency and volatility of wind and solar power hinder their large-scale integration. Chemical energy carriers (e.g., hydrogen, ammonia, methanol) have emerged as promising solutions for electrical energy storage to address this challenge. This study proposes a novel wind-solar-thermal-storage-hydrogen-ammonia-methanol (WSTS-HAM) integrated energy system for DGW energy bases, aiming to mitigate fluctuations in renewable power output. On this basis, an integrated planning and scheduling model is established to minimize the base's annualized cost and determine the optimal system capacity configuration. An 8760-h annual chronological production simulation is conducted, and system performance is evaluated using two key economic metrics: levelized cost of ammonia (LCOA) and levelized cost of methanol (LCOM). Jiuquan City in Gansu is selected as a case study, where the WSTS-HAM system is analyzed based on local wind and solar resource endowments. Results demonstrate that wind-solar complementarity significantly improves system economic efficiency and identifies an optimal wind-solar ratio that minimizes energy storage capacity requirements, with the minimum LCOA and LCOM reaching 7006.75 CNY/ton and 8949.58 CNY/ton, respectively. Besides, analysis of thermal power phase-out impacts reveals that the system's reliance on battery storage increases, while total system cost and carbon emissions both decrease continuously. Sensitivity analysis indicates that coal price fluctuations exert a greater impact on LCOA than on LCOM, with maximum increases of 2.72% and 2.22%, respectively.

Proton exchange membrane (PEM) water electrolysis offers a promising route for green hydrogen production, yet balancing catalytic activity and durability remains challenging for oxygen evolution reaction (OER) catalysts in acid, particularly for non‐Ir‐based catalysts. Herein, we develop a template‐guided strategy to synthesize the metal–organic framework (MOF)‐derived RuZrCoCrCeO 2 solid solution with tunable multi‐metal heteroatom regulation. The catalyst demonstrates outstanding acidic OER performance, requiring only 179 mV overpotential to achieve 10 mA cm geo −2 and remarkable durability over 1500 h at 50 mA cm geo −2 with a negligible decay of 30.67 µV h −1 . An “electronic buffer” effect facilitates electron transfer from atomically dispersed Zr to Ru, forming asymmetric Ru─O─Zr bonds with enhanced metal–oxygen covalency, thereby preventing excessive oxidation of Ru species. A vicinal deprotonation mechanism was proposed, where lattice oxygen assists *OOH deprotonation with a lower energy barrier on Ru─O─M sites. A PEM electrolyzer with low Ru loading (0.37 mg Ru cm −2 ) achieves an industrial‐level current density of 1 A cm −2 at 1.66 V, corresponding to a low hydrogen cost of US$0.89 kg −1 below the US DOE target (US$2 per kg of H 2 ), and operates stably for 600 h at 200 mA cm geo −2 , demonstrating its practical potential for scalable, Ir‐free PEM electrolyzers.

ABSTRACT While nickel oxide (NiO x ) is widely employed as an efficient hole‐transport material, the surface Ni 3+ species required for effective transport are unstable and can drive unfavorable interfacial reactions with the perovskite layer. Herein, we introduce a tetraoxopyridine‐functionalized porphyrin molecule to stabilize a Ni 3+ ‐rich NiO x /perovskite interface through dual coordination. Two oxopyridines in porphyrin act as hard Lewis bases that coordinate with hard‐acidic Ni 3+ sites on NiO x , while the other two interact with Pb 2+ in the perovskite lattice. Such a situation reduces interface defect formation, slows degradation, and helps maintain film integrity, while the conjugated porphyrin macrocycle promotes efficient hole extraction. Devices with the modified NiO x reach the champion efficiency of 27.05% (0.062 cm 2 ) and 21.8% (21.54 cm 2 aperture area), retaining >95% of the initial efficiency after 2000 h of continuous 1‐sun operation at the maximum power point. This work establishes a robust molecular‐engineering route to stabilize surface Ni 3+ in NiO x and support high‐efficiency, long‐lived perovskite solar cells.

Ruthenium (Ru)-based catalysts are promising for acidic oxygen evolution reaction (OER) in proton-exchange membrane water electrolysis (PEMWE), yet they suffer from severe corrosion and over-oxidation. Herein, we synergistically integrated Ru/RuO2 heterostructures with pre-introduced oxygen vacancies (OV) within a porous carbon (PC) framework derived from ZIF-8. Theoretical calculations and mechanistic spectroscopy confirmed that the heterointerfaces and OV regulate electronic distribution, lower Ru oxidation state, and optimize intermediate adsorption, thereby switching the reaction pathway from detrimental lattice oxygen mechanism to favorable adsorbate evolution mechanism. The resulting OV-Ru/RuO2@PC catalyst exhibits a low overpotential of 234 mV at 10 mA cm−2 and ultra-long stability exceeding 1000 h. Assembled in PEMWE, it delivers 1 A cm−2 at 1.77 V with a negligible degradation rate of 59 μV h−1 over 500 h, surpassing commercial RuO2. This work establishes a biomimetically inspired strategy to address the activity-stability trade-off of Ru-based OER catalysts for practical PEMWE.

High penetration of photovoltaic (PV) generation requires coal-fired power plants (CFPPs) to operate under frequent deep peaking conditions, where conventional ultra-low-load operation can cause efficiency loss and higher fuel consumption. This study proposes and evaluates a start-stop deep peaking strategy for CFPPs and systematically compares it with conventional low-load continuous operation. Using actual operational data from a 2×660 MW supercritical CFPP, the technical feasibility, operational characteristics, and economic performance of the strategy are analyzed. The results show that short-term hot start-stop operation with 5–10 h shutdowns is technically feasible and already widely applied, with 81 events recorded within one year. During an 8-h deep peaking period, shutting down one unit while operating the other at 40

To realize the high efficiency and nearly zero emission for coal-fueled electric power generation plants, a novel coal-fueled semi-closed supercritical CO2 (sCO2) cycle is developed based on process splitting method, which splits the semi-closed cycle into the closed cycle formed by recycled CO2 and the open process related to other streams, i.e., fuel, oxygen and combustion products. In the proposed system, all process heat released from the open process is integrated with the efficient closed sCO2 cycle as the waste heat from the cycle cold-end is recovered for the coal-pre-drying and CO2 split from the sCO2 cycle is utilized as the agent for coal gasification to avoid the requirement of the steam generation. Furthermore, the recompression modification is also applied to the sCO2 cycle, which could save more recuperation heat to drive the closed sCO2 cycle. The effects of CO2 stream split points for gasification and recompression are also analyzed to optimize the thermodynamic performance of the overall system. Results show that for the scheme without recompression, the net efficiency reaches 48.42 % (based on lower heating value, LHV) after the adoption of low-temperature pre-drying and CO2 gasification, and the different CO2 split points from cycle hot end or cold end for gasification have little effect on the net efficiency. While, for the scheme with recompression, the net efficiency can be further improved, and the CO2 split from the top turbine for gasification is better than that from the bottom compressor. Finally, after optimizing the CO2 split point for recompression, the coal-fueled semi-closed CO2 cycle achieves a pretty high efficiency of 51.35 % (LHV).

With the rapid development of renewable energy power generation systems, heat-power decoupling technology has garnered increasing attention in recent years, as it resolves temporal and spatial mismatches between the electrical energy and thermal energy output of the combined heat and power units. A conventional approach employs steam-molten salt thermal storage; however, this technology is limited to storing only the sensible heat of steam, neglecting latent heat. To realize full utilization of steam thermal energy, an integrated system combining molten salt and steam accumulator is proposed. In this design, molten salt stores high-grade sensible heat from superheated steam, whereas the steam accumulator stores both the residual sensible heat and the latent heat released during steam condensation. Multi-criteria analyses of the thermodynamic and economic performance of the molten salt coupled steam accumulator system are performed to assess the techno-economic feasibility of the system, and the operational flexibility during a typical day is investigated. The results demonstrate that the heat storage proportion of the conventional steam-heated molten salt system is only 5.6 %, requiring 12 h of charging to supply 4.7 h of steam. In contrast, the molten salt coupled steam accumulator system realizes full energy storage with significantly enhanced capacity: merely 3 h of daytime charging sustains 10.5 h of continuous steam supply at night. The proportion of heat storage, overall energy efficiency, and exergy efficiency of the molten salt coupled steam accumulator system are 63.7 %, 63.5 %, and an impressive 84.7 %, respectively. The system can save 13.3 million Nm3 of natural gas annually, resulting in a 75.8 % reduction in natural gas consumption, while also reducing CO2 emissions by 27,755 tons per year. The net present value, static and dynamic payback period are 6.1 million dollars, 4.1 years, and 4.4 years, respectively. The rate of return on investment and the internal rate of return are 11.2 % and 32.1 %, respectively, demonstrating excellent techno-economic feasibility.

Most of biomass-fueled power generation technologies, capable of achieving negative carbon emissions through carbon capture and storage (CCS), face significant challenges due to their low net efficiency. The semi-closed cycle offers the dual advantages of near-complete carbon capture and high efficiency, making it a promising solution for sustainable power generation. This study integrates biomass gasification with the semi-closed cycle and proposes a novel negative carbon emission power generation system, in which all heat released from biomass gasification and synthesis gas combustion is integrated with the highly efficient supercritical CO2 cycle. Moreover, the mechanism of energy conversion and translation is revealed by the thermal cycle splitting analytical method, which can visually clarify the thermodynamic relationship between the fuel combustion and the supercritical CO2 cycle. The impact of different gasification agents (O2/O2&H2O/O2&CO2) on the system energy distribution is investigated. Compared to basic case (net efficiency of 49.76 %), the introduction of CO2 for biomass gasification boosts the net efficiency (49.94 %), while adding H2O decreases it (49.16 %). Furthermore, sensitive analysis of the key parameters is conducted to optimize the net efficiency. Results show that the highest net efficiency is 50.14 % with the specific carbon emission of -673.00 gCO2/kW & sdot;h as the gasification temperature and the CO2 to fuel ratio are 1000 degrees C and 0.80, respectively.

Solar radiation and operation condition greatly influence solar aided coal-fired power generation（SACFPG） system.Based on a SACFPG system with its operating strategy considering both different direct normal insolation（DNI） and off-design load,a comprehensive criterion based on gray relation analysis considering the economic,thermal and environmental performance is proposed and used to evaluate of the annual performance of SACFPG system with/without storage under various policy conditions.It is found that solar subsidy,carbon tax,fuel price and the size of the solar field influence system's performance greatly.The results show that the initial investment of a SACFPG system is higher and the dynamic payback period is longer,but the addition of solar energy makes the total thermal efficiency higher and the environmental performance better.Specifically,the SACFPG system with storage has the highest thermal efficiency of 44.38% and the lowest CO 2 emissions of 0.1114 kg/kWh.Under polices of solar subsidy and carbon tax,the economic performance is remedied.Therefore,according to the proposed comprehensive evaluation criteria,SACFPG system with storage is the highest at 0.667,followed by coal-fired plant and SACFPG without storage is the worst.With the development of technology,the costs of SACFPG systems would be lower,and the future of SACFPG is even brighter.

Multi-energy complementary distributed energy system (MECDES) is an important development direction for the energy system. It has the advantages of energy conservation and environmental protection and has great potential to realize efficient energy cascade utilization through the energy conversion and utilization of cooling, heating, and power in place, achieving a user-oriented energy supply. The present study thoroughly reviews the current research status and puts forward the key scientific issues that urgently need to be resolved by investigating the problems and challenges of the MECDES from the perspectives of the characterization of the energetic mass-energy potential, the synergistic transformation and energy-potential coupling mechanism of multi-energy complementation, energy quality improvement and storage, and proactive regulation of the MECDES. Furthermore, the latest research progress of the MECDES for trickling the key scientific issues is comprehensively presented by proposing the distributed energy system with the complementation of multi-energy sources, developing novel ways of the energy potential coupling and energy cascaded comprehensive utilization of multi-energy complementation, proposing a new theory of multi-energy complementation and energy potential coupling and a new mechanism of source complementation, processing matching and thermodynamic cycle system collaborative conversion of both the fossil energy and renewable energy, and developing a new method of proactive adjust and control for adapting to fluctuating energy input and various energy load demands. Finally, the prospects and recommendations for the future research and development direction of MECDES are provided.

The semi-closed CO2 power cycle is a promising technology for efficient and clean fossil fuel utilization, providing high net efficiency and zero carbon emissions. To identify the optimal configuration for the semi-closed cycle, this study proposes an innovative free-superstructure method that combines evolutionary algorithms for the synergistic optimization of structures and parameters to achieve maximum efficiency. The improved optimization method surpasses conventional approaches based on predefined superstructures by expanding the search space. The results indicate that the net efficiency of the semi-closed CO2 power cycle system (OPT-2 case), optimized using the proposed method, increased from 40.18% to 45.53%. Furthermore, the net efficiency is 1.39 percentage points higher compared to the conventional optimization (OPT-1 case), due to the well-matched heat recovery process and reduced turbine exergy destruction. The study would provide an innovative and efficient method for the optimal synthesis of the semi-closed CO2 power cycle.

Solar aided coal-fired power generation (SACPG) is the most efficient and economical technology for reducing coal resource consumption and increasing solar energy efficiency by integrating solar thermal with conventional coal-fired power generation systems. This paper reviews the recent research progress of solar aided coal-fired power generation systems, including integration schemes, analytical methods, optimization methods and engineering applications. Firstly, according to the solar collector type, the integration schemes are categorized into trough, tower, combined trough-tower and non-concentrating flat plate, and the application of energy storage technology in the SACPG system is introduced. Secondly, the performance analysis of the complementary system is introduced including energy analysis, exergy analysis, environmental performance analysis and economic performance analysis, followed by a detailed summary of multiple solar contribution evaluation methods and optimization methods, and an analysis of the principle of each evaluation method. Finally, the current engineering application cases of solar aided coal-fired power stations in the world are summarized, and the outlook for the future development of SACPG system is presented.

An efficient integrated energy system (IES) can enhance the potential of building energy conservation and carbon mitigation. However, imbalances between user-side demand and supply side output present formidable challenges to the operational dispatch of building energy systems. To mitigate heat rejection and improve dispatch optimization, an integrated building energy system incorporating waste heat recovery via an absorption heat pump based on the flow temperature model is adopted. A comprehensive analysis was conducted to investigate the correlation among heat pump operational strategies, thermal comfort, and the dynamic thermal storage capacity of piping network systems. The optimization calculations and comparative analyses were conducted across five cases on typical season days via the CPLEX solver with MATLAB R2018a. The simulation results indicate that the operational modes of absorption heat pump reduced the costs by 4.4–8.5%, while the absorption rate of waste heat increased from 37.02% to 51.46%. Additionally, the utilization ratio of battery and thermal storage units decreased by up to 69.82% at most after considering the pipeline thermal inertia and thermal comfort, thus increasing the system’s energy-saving ability and reducing the pressure of energy storage equipment, ultimately increasing the scheduling flexibility of the integrated building energy system.