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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.

Abstract Gold nanoparticles (Au-NPs) seeded plasmonic nanofluids (PNFs) have shown promising results in overall performance enhancement of direct absorption solar collector (DASC) due to localized surface plasmon resonance (LSPR) effect. For the work presented here, Au-NPs were synthesized by the wet chemical method and were utilized to prepare plasmonic nanofluid. The surface plasmon resonance peak of Au-NPs was observed at 531 nm using UV–Visible spectrophotometer study. The testing for performance enhancement of gold plasmonic nanofluid (GPNF) laden DASC so far is limited to laboratory scale setups or simulation studies. Considering the dearth of outdoor experimental studies, an attempt has been made in the present study to evaluate the thermal performance of Au-NPs (∼40 nm) based nanofluid (∼0.0002 wt%) in full scale DASC. The experiments have been performed at different flow rates under clear sky outdoor conditions in winter season at Jalandhar, India. The maximum collector outlet temperature was measured to be 55 °C with GPNF which is about 7 °C higher than the maximum outlet temperature obtained with de-ionized water as working fluid. Thermal efficiency with GPNF is about 33% higher than de-ionized water at the optimal flow rate of 0.030 kg/s.

Abstract Designing a high-performance hydrofoil is a fundamental challenge for the current turbine blade designers. In this paper, the performance of S1210 hydrofoil, commonly used in the tidal current turbine blades, in presence of (i) Vortex Generators (VGs), and (ii) modified trailing edge is numerically studied. The results show that attaching counter-rotating VGs near the trailing edge of the foil can increase the lift coefficient by 17% and delay the stall angle from 10° to 12°. Constructing a rounded and thicker trailing edge can help to improve the hydrodynamic performance by increasing the lift coefficient by 13.5%. The combination of VGs (located near the trailing edge) and rounded trailing edge can increase the glide ratio significantly. These observations have been explained by plotting the pressure coefficients and velocity profiles at different locations on the foil surface. The findings will be useful to manufacture a stronger blade profile and extract more power from the current turbines that operate at wide current speed variation.

Abstract Enhancing microalgae biomass productivity through different abiotic and environmental factors optimization is crucial. Design of experimental (DOE) methodology using Taguchi orthogonal array (OA) was studied to evaluate the specific influence of eight important factors (light, pH, temperature, carbon concentration, nitrates, phosphates, magnesium ion concentration and carbon source) on the biomass production using three levels of factor (2 1 × 3 7 ) variation with experimental matrix [L 18 -18 experimental trails]. All the factors were assigned with three levels except light illumination (2 1 ). Substantial influence on biomass productivity is observed with carbon concentration contributing 16.8%, followed by nitrates 12.8% and light 9.3%. Experimental setup eight (Light, pH-8.5, Temperature 25°C, Carbon concentration 10 g/l, nitrates 1.5 g/l, phosphates 0 g/l, magnesium 150 mg/l, Carbon source (glucose)) showed maximum biomass growth (5.26 g/l) and good substrate degradation (63%, COD removal efficiency) contributing to carbohydrate production (257 mg/g biomass) which is further converted to lipids (20% Total lipid and 10% Neutral lipids). Chlorophyll ( a , b ), carbohydrates composition, FAME analysis for lipid percentage were monitored during process operation. Elemental analysis reveals that the carbon to hydrogen and oxygen ratio present in dried algal biomass can be hydrothermally liquefied (HTL) to produce biocrude.

Abstract Small hydropower projects (SHPs), though generally considered more environmentally benign and socially acceptable as compared to large projects, yet their overall sustainability is under suspicion in the Himalayan regions. Almost all SHPs in this region are being developed as run of the river mode which generally causes less/no submergence and quite less displacement of people as compared to large reservoir based hydropower production mode. However, in the absence of proper planning and monitoring mechanism, these projects are causing implacable tunnelling of hills, choking of streams, conversion of streams into dry ditches and long term socio-environmental impacts. This paper presents a SHP development study from hydro rich Beas river basin of Himachal Pradesh, a state nestled in western Himalayan region of India. In depth field studies, focus group discussions with the project affected people and interaction with project proponents of five SHPs in this region suggest that sustainability issues with respect to SHPs are not small vis-a-vis size of their installed capacity. There is an urgent need to take steps to include SHPs having an installed capacity of above 10 MW into the ambit of environment clearance process which is absent in many countries of the world at present.

Abstract Pongamia residue (shells) is the byproduct from the biodiesel processing industry, which is a lignocellulosic biomass material. It is not suitable as feedstock in downdraft wood gasifier due to low bulk density (146 kg/m3) of shells as compared to wood (more than 350 kg/m3). Pelletization and gasification of pelletized shells was carried out in the present work. The heat transfer analysis in pellets of 17 mm and 11.5 mm was also carried out to evaluate thermal properties of this biomass. Shell pellets of 17 mm and 11.5 mm diameter and length in the range of 10–60 mm were gasified in a 20 kWe downdraft wood gasifier. The complete gasification of pellets with 17 mm diameter could not be achieved because of less porosity and presence of larger thermal gradient within the pellets. The gasification efficiency was 73% for 17 mm diameter pellets which is lower than that of 11.5 mm diameter pellets which was 95%. The calorific value of producer gas generated from smaller diameter pellets was higher (4.66 MJ/N m3) as compared to larger diameter pellets (3.98 MJ/N m3). Tar formation during gasification of smaller diameter pellets was low as compared to larger diameter pellets.

Abstract In this research, photovoltaic thermal integrated thermoelectric cooler (PVT-TEC) collector has been analyzed, considering three different types of PV modules, namely opaque, semitransparent and Aluminium base. The analysis is based on two models namely, thermal model and artificial neural network (ANN) model. The advantage of ANN model is that it does not require several parameters and complex calculations, unlike thermal model. The performance of opaque PVT-TEC collector [Case 1] has been studied by considering air [Case 1a] and water [Case 1b] as working fluids. The overall electrical efficiency and thermal efficiency of [Case 1b] is greater than [Case 1a] by 1.9–2.8% and 20.8–21.8%, respectively. Also, the impact of base cover material of PV module has been discussed by evaluating and comparing the performances of [Case 1b] opaque PVT-TEC water collector, [Case 2] semitransparent PVT-TEC water collector and [Case 3] Aluminium base PVT-TEC water collector. The results demonstrate that the daily overall electrical energy gain, daily rate of thermal energy gain and daily overall exergy gain is the highest for [Case 3] Aluminium base PVT-TEC water collector. Further, the results calculated from thermal model have been compared with ANN model and a fair agreement has been achieved.

Abstract This paper proposes optimum green energy systems for electricity generation of island resorts in Malaysia. A combination of solar energy and wind energy as intermittent renewable energy sources with a fuel cell (FC) system and a battery storage energy system as a backup to the green energy system is introduced for this study. This system is eco-friendly, economical over the long-term, highly sustainable and reliable. In addition, a diesel-based energy system as a non-green system is compared with the proposed green system. National Renewable Energy Laboratory's (NREL) HOMER software is used to determine and compare the optimal configuration green energy system with the diesel-based energy system in terms of net present cost, sensitivity analysis and pollutant gas emission. The feasibility and assessment of the proposed system is evaluated by utilizing the load profile and considering the geographical condition of a village (Juara village in Tioman Island) with approximately 30 chalets located in southern Malaysia. HOMER uses two types of load profiles for each given year. The first load profile is used during the presence of tourists, and the second profile is used when the locals are the main inhabitants of the island. The optimization management for the green energy system is performed through unit sizing to find the optimum power management analysis and to perform cost analysis of the system. The potential of renewable energy as well as a diesel-based energy system to meet the power demand for such a stand-alone system is considered. Technically feasible and economically viable green energy systems as prospective plans are explored in this study.