To confront the dual challenges of energy security and ambitious carbon neutrality goals by 2060, green methanol projects are being prioritized as critical solutions for decarbonization in China. In this study, renewable hydrogen-integrated gasification systems were shown to achieve production costs in the range 454 – 510 ${\$}$/MT in the best-performing provinces in the northeastern regions. However, gasification-only systems coupled with carbon capture and storage under a grid power regime achieve even lower costs, 445-450 $ {\$}$/MT. Compared to fossil methanol, biomass-based methanol systems can achieve GHG emission reductions of 98.2-124.7%, avoiding 335-522 ktCO2-eq/yr. Carbon credit incentives will be critical in achieving cost parity with conventional methanol, as lower carbon prices currently favor hydrogen-integrated systems using variable renewable energy. Under aggressive decarbonization policies, cost reductions of 51-94% by 2060 can be achieved. Strategic biomass allocation could satisfy China's marine fuel demand while preventing 37-44 million tons CO2 emissions annually.
Hypersonic vehicles represent a new strategic frontier in aerospace technology, with the scramjet as their mainstream propulsion system. However, the scramjet presents significant challenges in thermal protection and electricity supply due to the long-term high-Mach-number operation and the lack of power drive shaft. Designing integrated cooling and power generation systems (ICPGSs) based on the supercritical CO2 Brayton cycle can effectively solve these problems, with the advantages of high efficiency, compactness and non-coking. Nonetheless, its long-term operation under off-design conditions deviates from the rated-design condition. A novel integrated design approach is proposed by combining ensemble learning with heuristic algorithms to ensure a truly optimal all-condition performance. Different from existing studies that treat off-design analysis as a post-hoc validation, this design approach embeds a feedback mechanism into the rated-design optimization through ensemble-learning-based surrogate models and a synchronous iterative optimization of design and operation through heuristic algorithms, resulting in an improvement of up to 21.59%, which yields both a lower heat dissipation load and a larger electricity supply capacity. To reduce the unacceptable time consumption of numerical solutions in the optimization process, six surrogate models are considered and compared. A rapid design method based on a Bayesian-optimized XGBoost model is proposed, which enables a rapid and accurate prediction of system performance under diverse conditions, with the reduction in time consumption reaching up to 96.88%, and the mean absolute percentage error being only 1.59%. The findings provide theoretical support for the optimal design of ICPGSs and the performance enhancement of scramjets.
Iron-Nitrogen-carbon (Fe-N-C) catalysts are promising substitutes for Pt-based catalysts in oxygen reduction reaction (ORR) for zinc-air battery. However, the sluggish kinetics of ORR on conventional Fe-N-C catalysts resulted from difficult desorption of *OH intermediate and the slow mass transfer significantly impede their practical application. Herein, a novel composite template-assisted strategy is proposed to prepare Fe-N4 sites on unusual fullerene-like curved surface featuring stretched Fe-N bonds and hierarchically porous structure (denoted as f-Fe-NC). With unique curved Fe-N4 sites and hierarchical porosity, f-Fe-NC exhibits an impressive half-wave potential (E1/2) of 0.91 V vs. RHE. Moreover, the mass activity of f-Fe-NC is nearly sevenfold of that of ordinary Fe-NC featuring planar Fe-N4 sites and microporous structure, and the turnover frequency of f-Fe-NC increases at exponent level compared to ordinary Fe-NC. Theoretical calculations demonstrate the reduced energy barrier of rate-determining step and favorable *OH desorption on f-Fe-NC because of the degradation of bond order of Fe-OH bond. Zinc-air battery based on f-Fe-NC exhibits a power density of 182 mW cm-2 and a specific capacity of 811 mAh g-1 at 10 mA cm-2, overtaking those of commercial Pt/C. Our study opens a new avenue for the rational design of electrochemically and structurally advanced ORR catalysts.
Hydrokinetic energy harvesting represents a promising direction for sustainable renewable energy generation, leveraging complex fluid-structure interaction (FSI) phenomena to convert water current kinetic energy into electrical power. This study presents a comprehensive investigation of a novel Vortex-Induced Motion (VIM) energy converter designed to maximize power extraction from marine and riverine environments. The research methodology integrates advanced computational fluid dynamics (CFD) modeling with rigorous experimental validation to ensure reliable performance characterization. A CFD model is developed to simulate fluid-structure interactions under diverse hydrodynamic conditions. Experimental verification is conducted through towing tank experiments, enabling robust model calibration and performance assessment. Key findings demonstrate the concept is capable of operating under a wide range of flow velocities, with numerical results confirming minimal performance degradation in near-wall configurations. This characteristic suggests significant potential for seabed deployment across varied marine infrastructures. A detailed parametric analysis systematically evaluates damping configurations, identifying optimal parameters for maximizing energy conversion efficiency. Economic feasibility analysis reveals competitive levelized cost of energy (LCOE) metrics, positioning the proposed energy converter concept as a technically and economically viable renewable energy solution for remote coastal and riverine applications.
The operating temperature of photovoltaic (PV) modules strongly affects electrical efficiency, reliability, and lifetime, yet existing thermal management solutions remain fragmented and difficult to translate into practical deployment. This review presents an engineering-oriented synthesis of PV cooling technologies, shifting the focus from isolated temperature reduction to system-level performance, deployability, and sustainability. Cooling strategies are systematically categorized into active, passive, environment-driven, and hybrid approaches, and evaluated using unified metrics including temperature reduction (typically ~3–50 °C), net energy gain (up to ~25% under favorable conditions), parasitic energy consumption, resource footprint, reliability, and technology readiness level (TRL 2–8).Based on this systematic categorization and evaluation, a decision-oriented cooling strategy selection framework is proposed to bridge the gap between laboratory-scale demonstrations and real-world deployment by linking climate conditions, installation constraints, and system objectives with scenario-matched cooling solutions. By explicitly addressing the fragmented nature of existing studies, this work reframes PV cooling as a multi-objective engineering design problem rather than a single-metric optimization task. The proposed framework provides actionable guidance for selecting and integrating cooling strategies across diverse PV applications and highlights future directions toward scalable, reliable, and resource-efficient photovoltaic thermal management.
This study experimentally investigates and comparatively analyzes the dynamic performance of a proton exchange membrane (PEM) electrolyzer during cold start, hot start, and load regulation. The experimental comparison specifically includes three cold start-up strategies: direct, single-step, and double-step; two hot start-up approaches: direct and multi-step; and two load regulation modes: direct and stepwise. To comprehensively evaluate the dynamic performance of the PEM electrolyzer, this study adopts indicators such as voltage rise rate, average efficiency, and average hydrogen production rate for assessment. To objectively determine the weights of each indicator, the entropy weight method was adopted. Subsequently, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was used to calculate the closeness coefficient of each operational strategy to the ideal solution, thereby quantifying their overall performance ranking. Results show that the single-step cold start-up strategy exhibits the best overall performance, with its voltage rise rate, average efficiency, and average hydrogen production rate being 2.32 mV/s, 69.68%, and 1.324 mmol/s, respectively. The multi-step hot start-up strategy demonstrates superior overall performance compared to the direct hot start-up, with corresponding indicators of 4.25 mV/s, 71.92%, and 1.315 mmol/s, respectively. The multi-step load regulation strategy exhibits significantly better overall performance than the direct regulation method, particularly during load-decreasing operations. The relative closeness coefficients are 0.2816 and 0.7184 for direct and multi-step load increasing, respectively, and 0.0196 and 0.9804 for direct and multi-step load decreasing, respectively. This study provides both experimental evidence and a comprehensive assessment framework for optimizing the dynamic operation strategies of PEM electrolyzers.
Natural gas hydrates (NGHs) represent a vast potential energy resource, yet their mechanical instability under geological or anthropogenic stresses threatens seafloor stability and poses climate risks. Using large-scale molecular dynamics simulations, we demonstrate how ultralow mechanical loss enables long-term stability in polycrystalline methane hydrates under cyclic shear. Our analysis reveals two distinct deformation regimes governed by grain size, temperature, and loading frequency. Under high-frequency, small grained methane hydrates undergo transgranular fracture, whereas large grained methane hydrates deform through elastic kink banding, maintaining structural coherence. Under low-frequency and elevated temperature conditions, which is characteristic of geological settings, the response becomes viscoelastic, with energy dissipation dominated by grain boundary activities including molecular diffusion, cage structure transformations, and sI ↔ sII phase transitions. These grain boundaries, enriched in metastable noncanonical cages, serve as dissipation hotspots where cage restructuring and phase transitions efficiently release strain energy. Crucially, the frequency-dependent mechanical loss follows the Cross model, exhibiting an ultralow loss tangent limit of 0.22 that underpins the exceptional stability of natural hydrate systems. This work establishes a molecular-to-macroscopic framework linking dissipation mechanisms to reservoir-scale stability, providing fundamental insights for assessing hydrate integrity under natural and anthropogenic perturbations.
Transforming polyethylene (PE) into high-value chemicals is often hindered by diffusion barriers. Here, we report a hydrogen-free strategy using pore-engineered hierarchical ZSM-5. By tuning desilication, we identified a critical pore–acidity synergy at an optimal Vmeso/Vmicro ratio of ~2.7 within this specific low Si/Al (25~50) framework. The optimal catalyst achieved near-complete conversion (98.8%) and an aromatic yield of 37.4% at a mild temperature of 280 °C. In-situ FTIR and molecular dynamics simulations reveal that this synergy facilitates a cascade reaction mechanism. The introduced mesoporosity enhances the effective diffusion coefficient of C10 intermediates by an order of magnitude (from 0.1 ×10−9 m2s−1 to 2.2×10−9 m2s−1), thus enabling rapid turnover and suppressing over-cracking. The hierarchical catalyst (Hier-Z5-43) demonstrated exceptional stability and versatility for real-world plastic upcycling. Techno-economic and life cycle analyses confirm substantial advantages, reducing energy consumption by 10.9 MJ/kg and decreasing global warming potential by >55% compared to conventional fossil-based routes. This study highlights the importance of synergistically optimizing pore structure and acidity to enhance catalytic performance in polyolefin upcycling.
The global transition toward decarbonized energy systems necessitates efficient long-duration energy storage solutions to address renewable intermittency. Conventional technologies face limitations in scalability, safety and geography, highlighting the promise of Carnot batteries. This study proposes a novel Carnot battery system integrating calcium hydroxide/calcium oxide thermochemical energy storage, supercritical CO2 Brayton heat pump and power cycles, and industrial waste heat recovery. Through multi-objective optimization using the NSGA-II algorithm and HEATSEP framework, the system achieved a round-trip efficiency of 67.95% and a LCOE of 1.200 RMB/kWh at 50 MW scale—placing it at a high level among current Carnot battery systems. Sensitivity analyses confirm robust scalability: when scaling from 10 MW to 50 MW, the LCOE decreases by 46.3% and the IRR increases from 6.79% to 13.64%. Furthermore, increasing the annual operating hours to 2560 h significantly reduces the LCOE while substantially raising the IRR. For high-cost materials, extending cycle life can yield 21.47% reduction in LCOE. Critically, system profitability is governed by discharge revenue. In markets with modest price differentials, economic feasibility therefore depends on additional reductions in capital cost, such as implementing deep integration with existing coal-fired assets. This integrated system and optimization directions provide a practical, generalizable blueprint for near-term, cost-competitive Carnot batteries.
Optimizing the selectivity of biomass-derived platform chemicals requires precise control over the geometric and electronic structures of catalytic active sites. Herein, we report the structural engineering of single-atom ruthenium (Ru1) supported on ceria (CeO2) nanocrystals with distinct crystal facets to regulate the hydrodeoxygenation of levulinic acid to 2-butanol. Using a facile photodeposition method, Ru1 species were anchored onto cubic (CeO2-C, exposing (1 0 0) facets) and sheet-like (CeO2-S, exposing (1 1 1) facets) supports. The Ru1CeO2-C catalyst exhibited superior catalytic performance, achieving an 86.9% yield of 2-butanol at 190 °C with a turnover frequency value of 157 s-1, surpassing the Ru1CeO2-S catalyst (53.5% and 111 s-1). Comprehensive characterization, including XPS, Raman spectroscopy, and EPR, revealed that the (1 0 0) facets of CeO2-C facilitate a higher concentration of surface oxygen vacancies and foster the electronic metal-support interaction. This interaction stabilizes Ru species and promotes the formation of Lewis acid sites, which are critical for the ring-opening of the key intermediate, γ-valerolactone. Kinetic studies, in situ DRIFTS, and theoretical calculations further confirmed that the facet-dependent electronic structure of Ru1CeO2-C significantly enhances hydrogen transfer capabilities and C-C bond cleavage efficiency. This work elucidates the structure-activity relationship in single-atom catalysis and offers a facet-engineering strategy for designing efficient biomass conversion catalysts.
Hydrogen production from offshore wind power is a key pathway for deep decarbonization, converting abundant wind energy into green hydrogen to support energy system transformation. This report systematically analyzes its technical pathways, resource potential, spatial distribution, and economic and environmental benefits, reviews the applicability of mainstream water electrolysis technologies, including alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE), and solid oxide electrolysis (SOEC) in marine environments. The study also compares three system configurations, i.e., offshore centralized, offshore distributed, and onshore centralized hydrogen production. Spatial analysis reveals significant regional agglomeration, with Zhejiang and Guangdong exhibiting the highest marine resource potential, while Liaoning and Hebei around the Bohai Sea showing strategic advantages due to their proximity to load centers and established infrastructure. Economically, strategic policy interventions could reduce electrolyzer costs by 40% in the near term and up to 80% over the longer term, according to IRENA. The IEA projects that the levelized cost of hydrogen from offshore wind could fall to approximately $1.5/kg by 2030 in favorable regions, achieving cost-competitiveness with blue hydrogen. Environmentally, the life-cycle carbon footprint of offshore wind-based hydrogen is only 0.4–0.8 kg CO2 eq/kg H2, significantly lower than the 9.3–11.9 kg CO2 eq/kg H2 of grey hydrogen. By prioritizing resource-rich coastal provinces with strong industrial bases, this approach offers a near-zero emission solution, providing a critical technical pathway toward achieving dual carbon goals.
