Abstract

This study investigates the techno-economic optimization of Pumped Hydro Storage (PHS) with integrated Floating Photovoltaic (FPV) systems, emphasizing two configurations. FPV modules, installed over water basins, exploit unused space, reducing water evaporation and enhancing photovoltaic efficiency via natural water-cooling. The Capriati PHS plant in Italy serves as the study case due to favorable irradiation conditions. The FPV model considers water cooling’s positive impact on PV cell efficiency and basin surface evaporation reduction. Historical meteorological data inform FPV production profiles, guiding an hour-based yearly optimization. Results reveal a substantial PHS utilization increase. In the first configuration, connecting FPV to the pump boosts Net Present Value and Equivalent Operating Hours (EOH) by around 60% and 40%, respectively. In the second configuration, grid interaction and electricity export lead to a 90% NPV increase and a 20% EOH increase. PHS-FPV integration enhances both PV and PHS productivity, offering a solution to challenges posed by seasonal PV production fluctuations.

Abstract

Global warming and climate change caused by greenhouse gas emissions have become urgent issues. Light-enhanced reverse water gas shift (RWGS) process is capable of efficiently converting CO2 to CO at a low temperature with impressive rates by the La0.8Sr0.2FeO3-supported Ni-Fe alloy (Ni-Fe/LSF). We test the reactivity of RWGS driven by pure thermal and photo-thermal coupled conditions in the same flow fixed-bed reactor. The results indicate that the apparent activation energy of RWGS reaction decreases by nearly 50% under direct light irradiation, and the CO production rate is enhanced by 2 times. In addition, the effects of light intensity on the reaction performance of CO2 hydrogenation reaction and long-term stability are investigated. The formation of (Fe, Ni) phase is conducive to the high reactivity of the catalyst during long-term operation. By combining a suitable concentrating solar system, a matched photo-thermal reactor and optimizing the operating conditions, it is expected to achieve highly efficient CO2 conversion at low temperatures through solar energy utilization.

Abstract

Understanding the dynamic behavior of low Pt-loaded proton exchange membrane fuel cells (PEMFCs) subjected to rapid load changes is a prerequisite for ensuring reliable devices suitable for transportation applications. The dynamic cell response requires the coupled solution of all the involved processes. To this end, a multiphase non-isothermal pseudo-three-dimensional (P3D) model coupled with a detailed electrochemical sub-model is adopted for a straight fuel cell portion to evaluate the cell dynamic response under the Galvano-dynamic condition. In addition, the mixed wettability model is incorporated to account for the microstructural properties of different porous layers. The effect of catalyst salient features including Pt-loading, ionomer to carbon weight ratio (I/C ratio), additional bare carbon particles, and CL thickness as well as operating conditions including relative humidity and stoichiometry ratios are studied under load cycling.

Abstract

Epoxy resin-reinforced graphite composite materials have found significant applications in the construction of fuel cell bipolar plates under stable power supply, owing to their lightweight and high durability characteristics. These composite materials are formulated by blending graphite with thermosetting resin and curing agent. The interfacial bonding between graphite and epoxy resin plays a pivotal role in determining the performance of these composites. Typically, the bonding between graphite and resin is governed by van der Waals forces, which possess relatively lower binding energy, rendering the interface susceptible to failure under external forces. To address this limitation, this study endeavors to modify the graphite surface with functional groups and adjust the process to facilitate a chemical bonding interface between graphite and resin. Characterization techniques reveal the formation of new chemical bonds between graphite and resin. Molecular dynamics simulations further validate the detailed mechanism through which this enhanced interface bonding elevates the mechanical performance of the composite material. This investigation offers valuable insights for the advancement of graphite-resin composite materials.

Abstract

In order to store CO2 efficiently and safely, the innovative approach of storing CO2 in the water cut reservoirs entering the later stage of heavy oil development through high quality foam was proposed. Due to the high apparent viscosity of foam, the heterogeneity of reservoir was regulated, the CO2 mobility was controlled, and the CO2 storage efficiency was increased. In this paper, the influence of foam quality and reservoir permeability on CO2 storage efficiency and oil recovery was researched through sandpack model experiment. In addition, in order to truly simulate the water-cut reservoir, the three-dimensional model was designed. The variation laws of gas saturation, mobility reduction coefficient, and CO2 storage water consumption with the foam quality were summarized. The experimental results indicated that when the foam quality was 85%, the gas saturation of the water-cut reservoir was the highest, reached 75.36%, reflecting the high CO2 storage efficiency and the mobility control ability. Moreover, the water consumption for CO2 storage also dropped to the lowest, reached 43.88 g·mol-1, representing the high quality foam has good CO2 storage ability.

Abstract

The Chinese government’s net zero plan targets climate neutrality by 2060, emphasizing a shift in power generation from coal to variable renewable energy sources (VRES), reaching 29% in 2020. Integrating VRES necessitates a Smart Grid, managing energy flow bidirectionally and mitigating source variability. This study evaluates Smart Grid investment’s economic gains in China via a cost-benefit analysis. Forecasting from 2020 to 2050, the analysis predicts a 6.1:1 Benefit-to-Cost ratio, akin to EPRI findings. However, data limitations warrant acknowledgment.
This paper seeks to explore the potential financial merits of deploying Smart Grids in China amidst transitioning to sustainable energy sources.

Abstract

The operating performance of lithium-ion batteries will degrade in extremely cold environments. A thermal management system for cold temperatures to make the lithium-ion batteries work in a reasonable temperature range is significant. This paper proposes a low-temperature battery thermal management system based on composite phase change material that preheats batteries quickly under cold environments with heating effect. The chosen CPCM of paraffin (82 wt%), graphite (15 wt%) and electrolytic copper powder (3 wt%) has the leakage rate of 4.43 %, the thermal conductivity of 6.256 W/(m·k), the latent heat of solidification of 152.68 J/g, the latent heat of melting of 164.77 J/g, and at -30 °C the electrical conductivity of 0.357 S/cm. Under the preheating effect of the CPCM, Lithium-ion battery can discharge at -30 °C with a small current. Furthermore, the CPCM rapidly heats up the single battery from -20 °C to 10 °C after the current flows through it, a process that consumed only 258 s (1 C) and 189 s (2 C), and the maximum temperature difference between the various parts of the battery is 4.2 °C and 4.8 °C, respectively. The results of the battery preheating test show that the chosen CPCM has good heating capacity, thermal uniformity and thermal conversion efficiency.

Abstract

The thermal emissivity of selective solar absorbers is a critical determinant of their operational efficiency. This paper details the computation of hemispherical emissivity for multi-layered coatings, specifically designed and optimized for solar thermal applications, particularly within high vacuum flat collectors at temperatures up to 200°C. We employed a MATLAB script, underpinned by the transfer matrix method, to calculate the hemispherical emissivity. The calculated emissivity values aligned well with experimental measurements derived from sputter-deposited samples. Our findings underscore the efficacy of the designed multi-layered coatings in relation to their thermal emissivity characteristics, thus highlighting their potential for solar thermal applications.

Abstract

Shale oil reservoirs are dense and characterized by ultra-low porosity and ultra-low permeability, which are usually developed effectively by horizontal wells and large-scale volume fracturing. However, with the continuous advancement of the development process, the formation pressure decreases, and the stress sensitivity problem brought about by the force compression of the effective seepage channels in shale becomes a key factor restricting the development effect. In this paper, two shale cores with different lithologies from Xinjiang Oilfield in China are used as research objects to conduct stress sensitivity simulation experiments under simulated reservoir in-situ conditions. Meanwhile, the whole rock XRD analysis and nanoindentation mechanical property test are combined to investigate the influence of shale mineral composition and mechanical properties on stress sensitivity. The experimental results show that mudstone shale has higher clay mineral content, and its elastic modulus and hardness are lower than that of sandy shale with high brittle mineral content. In addition, the maximum permeability loss rate of both shales exceeds 50%, which indicates that the stress sensitivity is stronger, among which the mudstone shale has stronger stress sensitivity. In addition, the stress sensitivities of the two shales with different lithologies also show some differences, with mudstone shale having a higher clay mineral content, a lower modulus of elasticity, a higher plasticity, and a harder crack recovery after stress recovery, and its stress sensitivity is higher than that of sandy shale with a higher content of brittle minerals. The stress sensitivity experiments carried out in this paper under in situ conditions in shale reservoirs clarified the control law of mineral composition and mechanical properties on stress sensitivity, which can provide more accurate data reference for the optimization of production system in shale reservoirs.

Abstract

In order to introduce renewable energy and electric vehicles in a coordinated manner, the complementary relationship between them needs to be quantitatively identified and policies developed. Therefore, this study conducted a time-series evaluation based on electric vehicle demand, solar power potential, and electric vehicle potential in Japan. As a result, it was found that many municipalities can achieve more than 99% self-sufficiency in the maximum introduction case, however in urban areas, renewable energy and electric vehicles alone cannot achieve net-zero self-sufficiency. Furthermore, it was found to be affected by charging restrictions. It is importance of peak shifting by charging other types through non-automobile recharging.