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Abstract This paper reports the fabrication of c-Si based solar cells using spin-on dopants. Solar cells were developed by texturing both surfaces of the c-Si, and forming the p–n junction by spin-coating the n-type dopant followed by rapid thermal processing (RTP). For back surface field formation on the rear side, a similar spin-coating step was undertaken for one cell and e-beam Al deposition for the other. In the case of double-sided spin-coated cell, simultaneous p–n junction and back surface field were formed in one RTP cycle. Without using high performance features in the device, double-sided spin-on doped cell showed Voc of 600 ± 0.01 mV, Jsc of 33.1 ± 0.03 mA/cm2, FF of 74.26 ± 0.06% and efficiency of 14.74%. As compared to single-sided spin-on doped cell, an improvement in efficiency of about 1.3% has been obtained which can be attributed to boron back surface field. Double-sided spin-on process significantly reduces thermal budget and improves throughput. Besides texturization, high efficiency features have not been used in the device. The results clearly demonstrate that c-Si based solar cells are potentially cost effective to manufacture.

Understanding and simulating the dynamic characteristics of the hydro-turbine governor system is essential to guarantee the safety of the hydro-power systems. This study proposes a modification method of the water head at the draft tube inlet, which is to discretize the draft tube and introduce the excitation term of the vortex rope. The proposed approach is applied for the modeling of the hydro-turbine governor system. The proposed model (Model I) is verified by means of a comparison with a second model (Model II) of the hydro-turbine governor system model without considering the vortex rope and verified against the experimental data during the load reduction. The model developed is accurate providing errors of the water head, inlet water head and flow of the hydro-turbine for Model ¿ are within ±3.3%, ±2% and ±5%, respectively. The proposed model overcomes the limitations of Model ¿ in the time-domain and frequency-domain since that only provides the average pressure at the draft tube, which do not reflect the pressure fluctuation and energy fluctuation. Instead the proposed model allows to capture and model the energy fluctuation during the load reduction as shown in the experimental results. The proposed model promotes the development of the hydro-turbine governor system model. Peer Reviewed

A Variable-Speed Wind Turbine (VSWT) can serve as a good reservoir of Kinetic Energy (KE) for few seconds owing to wide operating rotor speed. Based on this fact, several approaches have been proposed to introduce synthetic inertial response in VSWT. Usually, this is accomplished by introducing an additional control loop at the outer most level of the control hierarchy. However, several key issues including the selection of control parameters and the effects of wind speed variations on the synthetic inertial support are not addressed. As a result, the KE reserve is severely under utilized. To address these concerns, in this work, a simple approach is proposed to control parameter selection which ensures the optimal use of available KE reserve. Further, to tackle the variable KE reserve, a comprehensive inertia controller using intelligent learning paradigm is designed. The proposed inertia controller can adapt to wind speed variations while providing optimum inertial response. Efficacy of the proposed approach is evaluated over the entire operating range of the VSWT. For further evaluation, wind speed data from NREL western wind integration is utilized. The results indicate that the proposed system is quite effective and can maintain an adequate performance over the entire operating range.

Abstract Caprolactam is the main compound of nylon 6 waste fishing nets (WFNs) and its recovery conserves natural resources, maximizes WFNs economic performance, and closes the circular economy loop of the fishing net industry. Within the framework and as a part of the Healthy Seas’ initiative to clean the oceans from waste fishing nets (WFNs), and to valorise it, this research aims to study the catalytic pyrolysis behaviour of the WFNs extracted from oceans in order to study their potential applications in the energy conversion field. The catalytic pyrolysis experiments of WFNs over ZSM-5 Zeolite catalyst (2.5, 5, 10, 20, 50 wt%) were conducted using thermogravimetry (TG) coupled with Fourier-transform infrared spectroscopy (TG-FTIR) and gas chromatography–mass spectrometry (GC-MS) at different heating rates (5–30 °C/min). Also, the kinetics of ZSM-5/WFNs catalytic pyrolysis was studied by model-free methods (KAS, FWO, and Friedman). In addition, the distributed activation energy model (DAEM) and the independent parallel reaction kinetic model (IPR) combined with the optimization algorithm were used to fit the TGA-DTG experimental data and to calculate the parameters that can achieve the minimum deviation. The TGA results showed that the main decomposition zone was located in the range 342–476 °C with a total weight loss 83-75 wt% (based on the amount of catalyst). Meanwhile, FTIR and GC-MS results manifested that alkyl C–H stretch functional group, carbonyl functional group (C O), and caprolactam (83.15%; at 20 wt% of ZSM-5) are the main groups and volatile compounds in the decomposed WFNs samples. The model-free kinetics analysis showed that all activation energies were estimated at 112 kJ/mol (WFNs) and 158, 230, 197, 201, and 220 kJ/mol for ZSM-5/WFNs samples (2.5, 5, 10, 20, 50 wt%). At the same time, DAEM and IPR models proved a high prediction to fit TG curves at all heating rates. Based on these results, catalytic pyrolysis using 20 wt% of ZSM-5 can be used as a promising technology for extracting caprolactam from WFNs with high yield (83%). The recovered caprolactam can be used in the production of nylon fibres, nylon thin films, carpets, textiles, resins, etc.

Abstract The study analyzes application of Weibull probability distribution methodologies by summarizing wind power density in selected locations. Reliability of determination of Weibull probability density function of shape k and scale c parameters has been analyzed by means of eight methods. For the assessment of reliability of the methodology, root mean square error, coefficient of determination, chi-square test and relative error were calculated. Measurements of wind characteristics have been carried out in the coastal and continental part of the Lithuania. It has been determined that many calculation methods of the probability density function allow obtaining quite reliable results. However, depending on the geographical location of the area, the height from the ground level, and the influence of other factors on the wind power density, some methods are not acceptable, as they give over-large (up 13.44% and more) relative errors. A simulation model has been established to describe the wind power resources of locations with different climate conditions. For calculation Weibull parameters, it has been used 8760 of wind speed hourly data in 2014. The proposed model could be successfully used for the finding the suitable locations for development wind energy in regions which has the similar surrounding settings.

An experimental method for predicting the solar radiation intensity distribution incident on the absorber of a line-axis Compound Parabolic Concentrator (CPC) has been developed. A relationship has been derived that correlates insolation intensity with rate of temperature rise, based on first order time/temperature response curves obtained from thermocouples exposed to direct solar radiation. Employing this technique the energy flux distribution on the absorber of three line-axis CPC has been determined. The results have been validated with a,2-Dimensional raytrace analysis.

This paper presents a smart Transactive energy (TE) framework in which home microgrids (H-MGs) can collaborate with each other in a multiple H-MG system by forming coalitions for gaining competitiveness in the market. Profit allocation due to coalition between H-MGs is an important issue for ensuring the optimal use of installed resources in the whole multiple H-MG system. In addition, considering demand fluctuations, energy production based on renewable resources in the multiple H-MG can be accomplished by demand-side management strategies that try to establish mechanisms to allow for a flatter demand curve. In this regard, demand shifting potential can be tapped through shifting certain amounts of energy demand from some time periods to others with lower expected demand, typically to match price values and to ensure that existing generation will be economically sufficient. It is also possible to obtain the maximum profit with the coalition formation. In essence the impact of the consumption shifting in the multiple H-MG schedule can be considered while conducting both individual and coalition operations. A comprehensive simulation study is carried out to reveal the effectiveness of the proposed method in lowering the market clearing price (MCP) for about 15% of the time intervals, increasing H-MG responsive load consumption by a factor of 30%, and promoting local generation by a factor of three. The numerical results also show the capability of the proposed algorithm to encourage market participation and improve profit for all participants.

AbstractThis paper investigates the influence of wake interaction and blockage on the performance of individual turbines in a staggered configuration in a tidal stream farm using the CFD based Immersed Body Force turbine modelling method. The inflow condition to each turbine is unknown in advance making it difficult to apply the correct loading to individual devices. In such cases, it is necessary to establish an appropriate range of operating points by varying the loading or body forces in order to understand the influence of wake interaction and blockage on the performance of the individual devices. The performance of the downstream turbines was heavily affected by the wake interaction from the upstream turbines, though there were accelerated regions within the farm which could be potentially used to increase the overall power extraction from the farm. Laterally closely packed turbines can improve the performance of those turbines due to the blockage effect, but this could also affect the performance of downstream turbines. Thus balancing both the effect of blockage and wake interaction continues to be a huge challenge for optimising the performance of devices in a tidal stream farm.