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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.

The Severn Estuary has the world's second largest tide range and a barrage across the estuary, located just seawards of Cardiff in Wales and Weston in the South West England, has been proposed for over half a century, with the objective of extracting large amounts of tidal energy. A Severn Barrage, as previously proposed by the Severn Tidal Power Group (STPG), would be the largest renewable energy project for tidal power generation in the world, if built as proposed, and would generate approximately 5% of the UK's electricity needs. However, concerns have been raised over the environmental impacts of such a barrage, including potential increase in flood risk, loss of intertidal habitats etc. In addressing the challenges of maximizing the energy output and minimizing the environmental impacts of such a barrage, this research study has focused on using a Continental Shelf model, based on the modified Environmental Fluid Dynamics Code (EFDC) with a barrage operation module (EFDC_B), to investigate both the far and near field hydrodynamic impacts of a barrage for different operating scenarios. Three scenarios have been considered to simulate the Severn Barrage, operating via two-way generation and using different combinations of turbines and sluices. The first scenario consisted of 216 turbines and 166 sluices installed along the barrage; the second consisted of 382 turbines with no sluices; and the third consisted of 764 turbines and no sluices. The specification of the sluice gates and turbines are the same for all scenarios. The model results indicate that the third scenario has the best mitigating effects for the far-field and near-field flood risks caused by a barrage and produces the most similar results of minimum water depth and maximum velocity distributions to those obtained from simulating the natural conditions of the estuary, i.e. the current conditions. The results also show that the flow patterns around the barrage are closest to those for the existing natural conditions with minimal slight changes in the estuary. Thus, the results clearly indicate that the environmental impacts of a Severn Barrage can be minimized if the barrage is operated for two-way generation and under the third scenario. Although it appears that the energy output for the third scenario is less than that obtained for the other two scenarios, if very low head (VLH) turbines are used, then the third scenario could generate more energy as more turbines could be cited along the barrage structure. Therefore, the study shows that a Severn Barrage, operating in two-way generation and with 764 turbines (ideally VLH turbines), would be the best option to meet the needs of maximizing the energy output, but having a minimal impact on environmental changes in the estuary and far-field.

Abstract γ-Valerolactone (GVL)/water/acid has been developed as a mild solvent system to pretreat biomass. In this study, Eucalyptus was pretreated with 80/20 GVL/water with the addition of H2SO4 (20–100 mM) at 120 °C for 30–60 min, and the resulting cellulose-enriched residual fractions were further enzymatically hydrolyzed. Results showed that the pretreatment of Eucalyptus with GVL/water/acid system led to a significant decrease in the contents of lignin and hemicelluloses, and the enzymatic hydrolysis efficiency of the pretreated sample was significantly improved. Meanwhile, the removal of lignin and hemicelluloses from the cell walls during the pretreatment process was monitored by the confocal Raman spectra. Under the optimum conditions (50 mM H2SO4 and 60 min), the delignification rate was up to 90.7% and the cellulose content in the residue was reached to 86.1%. The high cellulose content led to a high cellulose conversion rate and the glucose yield was 6.1-fold higher than that of the raw material without pretreatment. In short, this process provided an efficient approach to remove hemicelluloses and lignin from Eucalyptus to enhance enzymatic hydrolysis for bioethanol production.

Renewable energy has become more popular since it is cost-effective and more efficient than conventional energy sources. Biomass-based renewable energy is primarily used in emerging economies to ensure environmental sustainability. This study examines the asymmetric correlation between biomass energy consumption and CO2 emissions in the top-10 biomass energy consumer countries (Brazil, Canada, Thailand, China, Italy, India, Germany, USA, UK, and Japan). A new approach "Quantile-onQuantile (QQ)" is employed by utilizing the data from 1991 to 2018. Biomass energy consumption, with the exception of Thailand, significantly mitigates CO2 emissions at various quantiles in selected countries. As a robustness check, we used the quantile regression test, whose findings are consistent with the outcomes from the quantile-on-quantile method. However, the degree of asymmetry in the biomass energy-CO2 nexus varies by country, necessitating extra attention and government vigilance when developing biomass energy and environmental policies.

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