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Abstract This paper uses research-quality, ground measurements of irradiance and temperature that are accurate to ±2% to estimate the electric energy yield of fixed solar modules for utility-scale solar power plants at 18 sites in Saudi Arabia. The calculation is performed for a range of tilt and azimuth angles and the orientation that gives the optimum annual energy yield is determined. A detailed analysis is presented for Riyadh including the impact of non-optimal tilt and azimuth angles on annual energy yield. It is also found that energy yield in March and October are higher than in April and September, due to milder operating temperatures of the modules. A similar optimization of tilt and azimuth is performed each month separately. Adjusting the orientation each month increases energy yield by 4.01% compared to the annual optimum, but requires considerable labour cost. Further analysis shows that an increase in energy yield of 3.63% can be obtained by adjusting the orientation at five selected times during the year, thus significantly reducing the labour requirement. The optimal orientation and corresponding energy yield for all 18 sites is combined with a site suitability analysis taking into account climate, topography and proximity to roads, transmission lines and protected areas. Six sites are selected as having high suitability and high energy yield: Albaha, Arar, Hail, Riyadh, Tabuk and Taif. For these cities the optimal tilt is only slightly higher than the latitude, however the optimum azimuth is from 20° to 53° west of south due to an asymmetrical daily irradiance profile.

Funding Information: This work was supported Southeast University (SEU) project 3203002003A1 and National Natural Science Foundation of China (NSFC) under the grant 51772080 and 11604088 . Jiangsu Provincial Innovation and Entrepreneurship Talent program Project No. JSSCRC2021491 . Industry-University-Research Cooperation Project of Jiangsu Province in China , Grant No. BY2021057 . Dr. Asghar thanks the Hubei Talent 100 program and Academy of Finland ( 13329016 , 13322738 ) for their financial support. Publisher Copyright: © 2022 The Authors Electrolytes with high-proton conduction and low activation energy are attractive for reducing the high operating temperature of solid-oxide fuel cells to less than <600 °C. In this work, we have fabricated semiconducting electrolyte SrFeTiO3-δ (SFT) material exhibiting high ionic conduction and exceptionally high protonic conduction at low operating temperature but with low electronic conduction to evade the short-circuiting issue. The prepared fuel cell device exhibited high open-circuit voltage (OCV) and a high-power output of 534 mW/cm2, of which 474 mW/cm2 could be for sure be related to the protonic part. The current study suggests that usage of semiconductor SrFeTiO3-δ facilitates a high concentration of oxygen vacancies on the surface of SFT, which mainly benefits proton conduction. Moreover, lower grain boundary resistance leads to obtain higher performance. Also, the Schottky junction phenomena are proposed to inhibit the e-conduction and excel the ions transportation. The high performance and ionic conductivity suggest that SFT could be a promising electrolyte for protonic ceramic fuel cells. Peer reviewed

The emission characteristics of particulate matters from a full-scale biomass-fired power plant equipped with bag filters were investigated. Results show that particle size distribution at the inlet of bag filter from the combustion of blended feedstocks is bimodal, while that of dry bark feedstocks is essentially unimodal with negligible emission of coarse particles with diameter in the range of 1.0–10 μm. The combustion of blended fuels generates higher yields of submicro particles than that of dry bark feedstocks. Elemental analysis shows that submicro particles in all cases mainly consist of potassium, chlorine, and sulfur. Higher chlorine but lower sulfur contents are observed in submicro particles from blended fuels compared with that from dry bark feedstocks. The vibrating operation of grate furnace reduces submicro particles emission as well as the sulfur content in all particles. Ion chromatography results show that sulfate ion and chloridion are the two most abundant water-soluble anions in particulate matters, while water-soluble cations are richest in potassium with considerable content of calcium, magnesium, sodium and ammonia. The contribution of organic and element carbon in particulate matters is in the range of 1–3%, indicating high combustion efficiencies and low organic and element carbon emissions of biomass-fired grate furnaces.

Abstract The sale of value-added byproducts from hydrogen-generating reactions is a strategic approach to lower the costs of hydrogen fuel in order to realize a truly sustainable hydrogen economy. Metal hydrolysis is a chemical process that produces hydrogen together with a metal hydroxide species; however, this reaction is rarely observed without chemical additives or extreme reaction conditions. Previously, we demonstrated that hierarchical nanoporous aluminum can create hydrogen at standard conditions for temperature and pressure via hydrolysis without any additives. The advantage of this method is the co-production of pure aluminum hydroxide (Al(OH)3). Here we explore the transformation of this Al(OH)3 hydrolysis byproduct into valuable materials to elucidate strategies in reducing the overall cost of hydrogen generated. In particular, we demonstrate in this work that (i) the synthesis of hierarchical nanoporous aluminum is scalable to meet the needs of large-scale production for a hydrogen economy, and (ii) the Al(OH)3 hydrolysis byproduct can be transformed to create high surface-area “activated alumina” (Al2O3) as a commercially viable product.

Abstract Thermal energy storage (TES) using phase change materials (PCMs) is being widely considered as one of the alternative solutions for effective use of solar energy. This paper presents a multi-objective optimisation strategy for TES systems using PCMs for solar air systems, in which two performance indicators of average heat transfer effectiveness and effective PCM charging time were used as the conflicting objectives. The influence of the key design variables on the performance of an air-based PCM TES system was first experimentally investigated using Taguchi method, and the results were used to develop two performance models for optimisation. A genetic algorithm was used to search for an optimal Pareto front and a multi-criteria decision-making process was employed to determine the compromise optimal solutions. The results showed that the average heat transfer effectiveness of the PCM TES system can be improved from 44.25 to 59.29% while the effective PCM charging time increased from 4.53 to 6.11 h when using the solutions identified by the proposed strategy with the weighting factors of 0.5/0.5 for both objectives, in comparison to a baseline case. A further comparison showed that the optimal design identified by the proposed strategy outperformed the two designs identified using Taguchi method.

Abstract This paper presents a numerical study on the hydrodynamic performance of a vertical pile-restrained wave energy converter type floating breakwater. The aims are to further understand the characteristics of such integrated system in terms of both wave energy extraction and wave attenuation, and to provide guidance for optimising the shape of the floating breakwater for more energy absorption and less wave transmission at the same time. The numerical model solves the incompressible Navier-Stokes equations for free-surface flows using the particle-in-cell method and incorporates a Cartesian cut cell based strong coupling algorithm for fluid-structure interaction. The numerical model is first validated against an existing experiment, consisting of a rectangular box as the floating breakwater and a power take-off system installed above the breakwater, for the computation of the capture width ratio and wave transmission coefficients. Following that, an optimisation study based on the numerical model is conducted focusing on modifying the shape of the floating breakwater used in the experiment. The results indicate that by changing only the seaward side straight corner of the rectangular box to a small curve corner, the integrated system achieves significantly more wave energy extraction at the cost of only a slight increase in wave transmission.

As wind power penetration increases, large wind farms (WFs) need to provide reactive power according to modern grid codes. Permanent magnet synchronous generator-based wind turbines (WTs) can generate reactive power, by assigning the appropriate reactive power to each WT to meet the reactive power requirements of the grid. This is a more economical method than setting up additional reactive power compensation equipment. This study proposes an optimal reactive power dispatch strategy for minimising a levelised production cost, and is implemented in two ways: minimising the power loss of a WF, and maximising the lifetime of WTs. The reactive power references of each WT are chosen as the optimisation variables, and a particle swarm optimisation algorithm is adopted to solve the optimisation problem. The proposed and traditional reactive power dispatch strategies are demonstrated and compared on a WF with 25 WTs to validate the effectiveness of the proposed approach.

This paper investigates the model test research of a semisubmersible floating wind turbine. An improved method is proposed to correct the deficient thrust force in a Froude-scale experimental condition, which is able to simulate the rotor operational state more realistically by allowing the rotor to rotate freely with the wind. This approach also maintains tip speed ratio to some extent and overcomes previously reported negative effects produced by common correction ways. Reduced platform resonant motions in the presence of wind force are observed. Due to rotor rotation, resonant yaw and roll motions are induced even in heading wind and wave state. Tower vibration is found to be suppressed by the wind force. Multi-frequencies components are observed in the response of tower-top shear force, which is governed by the couplings of hydrodynamic loads, aerodynamic loads and tower vibration. It is also found that the dynamic response of the mooring line is mainly dominated by wave load and aerodynamic effect can be simplified as an extra constant force.