Search

One of the most challenging issues in the domain of renewable energy is the instability of produced power. To put it another way, renewable resources such as solar energy cannot provide continuous energy supply because they rely on natural phenomena that vary randomly. That said, to cover the potential lack of energy that may occur, hybrid renewable energy system can be adopted. In other terms, instead of using single renewable energy source, two different sources can be utilized in order to optimize the output power all over the year. Furthermore, complementary energy system is needed along with renewable sources, to store energy and insure the supply during shortage period. With this in mind, a Green-Green energy system can be constructed by using green storage system such as Fuel Cell to be coupled with the renewable sources. In the light of green-green energy concept, the present paper examines a triple wind-solar-fuel cell combination in the aim of overcoming the energy shortage that occurs during several months of the year. A case study on the region of Dahr Al-Baidar in Lebanon is conducted to present the advantage of the proposed system. Results show that combining wind energy system with thermal solar system allows overcoming the low power produced by solar thermal system especially in winter. For illustration 16 kW are produced by wind turbine during the month of January, by contrast the thermal solar system provides 2 kW during the same period. Nevertheless, in June thermal solar offers 17 kW and wind turbine produces 11 kW.

This paper studies the effects of PhotoVoltaic (PV) tilt angle variation over the cost efficiency of PV networks. The monthly modification of the tilt angle β conducted by this study, decreased the levelized cost of energy (LCOE), thus enhancing the system's economical status, by reducing its capital investment's payback period. The intended outcome of this work is twofold: it corresponds to a generalized novel mathematical model which enables the maximum number of PV panels to be fit into a square shaped area without any mutual shading, plus it investigates the monthly tilt angle values based on a specific selection, and their effects on the LCOE. The application of the obtained results (i.e., numerical values of β) has diminished both the LCOE as well as the power cost, while increasing power production for a PV system located in Tripoli-Lebanon (latitude: 34.38°), Belfort-France (latitude: 47.63°) and Tantan-Morocco (latitude: 28.38°).

This paper aims at exploring different approaches utilized to track the Maximum operating Power Point (MPP) of PV (Photovoltaic) modules, fulfilling the largest amount of available power extraction, hence achieving cost and energy efficiencies of PV systems. This procedure takes place within two divisions: algorithm implementation and DC-DC Power Processing Units (PPUs) design. First and foremost, all MPP algorithms fall under two major categories: local MPP (happens during homogeneous solar radiations) and global MPP (occurs with partial shading conditions). Each of the two groups possesses various methodologies for algorithm generation. Secondly, PPUs were generally classified as either isolated or non-isolated DC-DC converters. Each collection reigns a buck, boost and buck-boost converters with diverse circuit layouts. A critical assessment and comparison were conducted for algorithms and converters in terms of efficiency, reliability and complexity. After analysis and comparison of different maximum power point tracking schemes, it is found that the best algorithm to be adapted is from the global maximum power point tracking set, under exploitation of characteristic curve topologies. For PPUs architecture, it is concluded that a non-isolated buck-boost converter is the best to be chosen while designing an MPP tracker.

The present work examines the combination of solar energy systems with Fuel cell. Indeed, fuel cells are green storage systems without any pollution effects. They are supplied by oxygen and hydrogen to produce electricity. That is why it is inescapable to find a source of hydrogen in order to use fuel cell. Several techniques can be adopted to produce hydrogen depending on the availability and the cost of the sources. One of the most utilized techniques is electrolysers. They allow to obtain hydrogen from water by several technologies among them proton exchange membrane (PEM) which is considered in this work. On the other hand, electrolysers need electrical power to operate. A green-green energy system can be constructed by using a renewable energy source to supply fuel cell trough electrolysers. A comparison between two solar systems (Photovoltaic and Parabolic Trough) coupled to fuel cell is performed. A case study on the Lebanese city of Tripoli is carried out. The study shows the performance of each of both combined systems for different parameters and proposes recommendations depending on the considered configuration.

The current tendency in energy domain is to reduce fuel consumption in favor of sustainable energy approaches. In this frame, the present work suggests an efficient way of heat recovery from boilers using concentric tube. The motivation behind the suggested concept is that it could be considered the cheapest, easiest to construct and simplest to use among all the existing heat recovery systems. In other words, the goal is to suggest a technique that could be utilized by a wider range of users regardless their technical level. Another advantage of the proposed concept is that is can be applied even on small scale boilers. With this in mind, a numerical tool is also developed allowing to make pre-studies to optimize the geometric parameters such as diameters and length, as well as to perform post-studies that allows to optimize operational parameters such as flow rates and fluids configurations. Furthermore, an experimental study is carried-out to validate the numerical results of the adopted heat exchanger. It was shown that water can be heated up to 100 °C depending on the flow rate and that the recovered heat increases through a rational function.

Geothermal heat pump is an efficient application derived from geothermal energy. It exploits earth as a heat provenance to extract heat from it and heat space in winter, or it uses earth as heat sink to transform heat to it and cool the space during summer. This paper presents a parametric study to investigate the effects of inlet and outlet water temperatures and ground temperature on the length of the pipe of a horizontal geothermal heat pump system during cooling process. The type of the considered pipe is Poliplex - PE100 Series 1 – polyethylene of 16 mm inner diameter and 20 mm outer diameter. The obtained results revealed that at 30 °C water inlet temperature, 27 °C water outlet temperature and 21 °C ground temperature the length of pipe needed is 716 m. Also, the results showed that higher water inlet temperature and ground temperature increases the required pipe length; however, higher water outlet temperature decreases the needed length of the pipe.

The main purpose of this paper is to design a clean and stand-alone power generator for isolated sites using renewable energy sources. The proposed system is able to operate without the need of refueling. The idea is to combine Photovoltaic Panels (PVs) with Fuel Cell (FC) to build an uninterrupted power generator. In presence of solar energy, PVs are used to feed the site with the required power as well as to produce hydrogen and oxygen using an electrolyzer. When solar energy becomes insufficient, the stored hydrogen and oxygen are used to feed the FC and produce electricity. The proposed system is modeled and controlled using Matlab-Simulink.

The overall efficiency of a PV system is strongly affected by the PV cell raw materials. Since a reliable renewable energy source is expected to produce maximum power with longest lifetime and minimum errors, a critical aspect to bear in mind is the occurrence of PV faults according to raw material types. The different failure scenarios occurring in PV system, decrease its output power, reduce its life expectancy and ban the system from meeting load demands, yielding to severe consecutive blackouts. This paper aims first to present different core materials types, material based fault occurring on the PV cell level and consequently the fault detection techniques corresponding to each fault type.