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In this work, Cu2O nanoparticles were successfully prepared onto the surface of two-dimensional graphitic carbon nitride (g-C3N4) by using a simple solution chemistry approach. An environment-friendly reducing agent, glucose, was used for the synthesis of Cu2O NPs onto the surface of g-C3N4 without using any surfactant or additives. The surface composition, crystalline structure, morphology, as well as other properties have been investigated using XPS, XRD, SEM, FTIR, FESEM, EDS, etc. The electrochemical measurements of the prepared materials demonstrated that Cu2O exhibited a weak oxidation activity towards urea, while g-C3N4 has no activity towards urea oxidation. The Cu2O supported on the surface of g-C3N4 (Cu2O-g-C3N4) demonstrated a significant activity towards urea oxidation that reached two times that of the unsupported one. The significant increase in the performance was related to the synergetic effect between the Cu2O and g-C3N4 support. The prepared composite materials demonstrated high stability towards urea oxidation as confirmed from the stable current discharge for around 3 h without any noticeable degradation performance.

This is an accepted manuscript of an article published byElsevier in Reference Module in Materials Science and Materials Engineering on 14/12/2020, available online: https://doi.org/10.1016/B978-0-12-815732-9.00061-9 The accepted version of the publication may differ from the final published version

This is an accepted manuscript of a chapter published by Elsevier in Reference Module in Materials Science and Materials Engineering on 22/10/2020, available online: https://doi.org/10.1016/B978-0-12-815732-9.00034-6 The accepted version of the publication may differ from the final published version

This paper studies the technical, economic, and environmental feasibility of a standalone adsorption cooling system that is thermally driven by biomass combustion and solar photovoltaic energy. The developed cooling package was benchmarked against a baseline vapour compression refrigeration system, driven by grid electricity and the widely investigated adsorption cooling system driven by solar heat. TRNSYS was utilised to imitate the integrated systems, investigate their performance throughout the year, and optimise their designs by employing the meteorological data for Rwanda and an existing cold room (13 m 2 floor area × 2.9 m height) as a case study. The optimisation study for the system revealed that maximum chiller performance (COP = 0.62), minimum biomass daily consumption (36 kg), and desired cold room setting temperature (10 °C) throughout the year can be achieved if the boiler setting temperature, heat storage size, and heating water flow rate are 95.13 °C, 0.01 m 3 and 601.25 Kg/h. An optimal PV area/battery size combination of 12 modules / 16 kWh was observed from the economic, environmental, and technical viewpoints.

This work presents a mathematical modelling of a proton-exchange membrane fuel cell (PEMFC) system integrated with a resistive variable load. The model was implemented using MATLAB Simulink software, and it was used to calculate the fuel cell electric current and voltage at various steady-state conditions. The electric current was determined by the intersection of its polarisation curve and applied as an input value for the simulation of the PEM fuel cell performance. The model was validated using a Horizon H-500xp model fuel cell stack system, with the following main components: a 500 W PEM fuel cell, a 12 V at 12 A battery for the start-up, a super-capacitor bank to supply peak loads and a 48 V DC-DC boost converter. The generated power was dissipated by a variable resistive load. The results from the model shows a qualitative agreement with test bench results, with similar trends for stack current and voltage in response to load and hydrogen flow rate variation. The discrepancies ranged from 2% to 6%, depending on the load resistance applied. A controlled current source was utilised to simulate the variation of fan power consumption with stack temperature, ranging from 36.5 W at 23 °C to 52 W at 65 °C. Both model and experiments showed an overall PEMFC system maximum efficiency of about 48%.

Lipid extraction from microalgae is maximized by defining the optimal operating conditions of the microwave pretreatment method. Using the experimental data, a robust model that describes the lipid extraction is generated using fuzzy logic. Then, the optimal extraction conditions of the lipid are determined using Particle Swarm Optimization (PSO) algorithm. Three different operating parameters influence on the recovered lipid from Microalgae. These parameters are power (W), heating time (min), and extraction time (h). Accordingly, during the optimization process, these parameters are used as a decision variables for PSO optimizer in order to maximize the recovered lipid that used as a cost function. The resulting plots demonstrated a well-fitting between the fuzzy model and the experimental data. Based on the built model, the optimization process achieved a significant increase in the lipid extraction by 22% compared to that obtained experimentally and using the ANOVA.

The process of extracting lipids from high-moisture Scenedesmus quadricauda microalgae biomass disrupted with microwave was examined. The study showed that microwave pre-treatment is effective in algae cell rupture while microwave power was found to be a significant factor to enhance the degree of cell disruption. Though microwave pre-treatment time had some effect, the degree of cell rupture seemed to decrease after a certain pre-treatment time. The total lipid from Scenedesmus quadricauda sp. were extracted using a mixture methanol and sulphuric acid as an organic solvent. In addition, it was discovered that microwave pre-treatment enhances the disruption of microalgae cells to attain a high level of lipid yields. Optimal lipid yield obtained in this study was 49% at power 600 W, heating time of 8 min and extraction time of 3.5 h.

This review critically evaluates the latest trends in fuel cell development for portable and stationary fuel cell applications and their integration into the automotive industry. Fast start-up, high efficiency, no toxic emissions into the atmosphere and good modularity are the key advantages of fuel cell applications. Despite the merits associated with fuel cells, the high cost of the technology remains a key factor impeding its widespread commercialization. Therefore, this review presents detailed information into the best operating conditions that yield maximum fuel cell performance. The paper recommends future research geared towards robust fuel cell geometry designs, as this determines the cell losses, and material characterization of the various cell components. When this is done properly, it will support a total reduction in the cost of the cell which in effect will reduce the total cost of the system. Despite the strides made by the fuel cell research community, there is a need for public sensitization as some people have reservations regarding the safety of the technology. This hurdle can be overcome if there is a well-documented risk assessment, which also needs to be considered in future research activities.

In this present study, microwave pre-treatment has been used for sustainable biofuel production from three different biowastes through catalytic aided co-pyrolysis techniques. The experimental investigations have been carried out to develop biofuel at temperature (350-550℃), heating rate (15-50℃/min) and particle size (0.12–0.38 mm). The resultant biofuels were characterized using TGA, DTA, FE-SEM, FTIR spectroscopy and NMR spectrum. The pyrolysis process of biomasses without and with catalyst resulted in the yield rate of 29–37% and 39–51% respectively. Moreover, the CaO catalytic co-pyrolysis process of pomegranate peel, groundnut shell and palmcone wastes with a ratio of 50:50 at 0.25 mm particle size has resulted in the highest yield rate of 51.6%. The NMR result of bio-oil samples produced hydroxyl group and aliphatics which clearly state the suitability of bio-oils for automotive application. The bio-oil had promising fuel characteristics consisting more energy density (29.1 MJ/kg), less oxygen content and free of nitrogen.

Microalgae biofuel is one of the most promising renewable energy sources that can contribute to the replacement of fossil fuels globally because of its sustainability and its ability to reduce the carbon dioxide emission in the atmosphere. However, the rigidity of microalgae of microalgae cell wall inhibits the extraction of lipids for biofuel production. To improve microalgae biofuel production, different pre-treatment techniques have been studied to evaluate their effectiveness on microalgae cell wall disruption. The main objective of this paper is to review the different pre-treatment technologies used in biofuel production from microalgae biomass and to critically discuss the current limitations and promising perspectives towards achieving economic and industrial scale production. Pre-treatment methods reviewed are categorized into mechanical techniques (e.g. high-pressure homogenizer and bead mills), physical techniques (e.g. ultrasonic and microwave methods), thermal pre-treatment techniques (e.g. autoclave and steam explosion), chemical techniques (e.g. catalytic and enzymatic), and combined techniques. Furthermore, comparisons of these techniques are discussed. The overall effect of the applications and methods on biofuel production together with energy consumption are critically examined.

The present study investigates the effect on methane production from waste paper when co-digested with macroalgal biomass. Both feedstocks were previously mechanically pretreated to reduce their particle size. The study was planned according two factors: the feedstock to inoculum (F/I) ratio and the waste paper to macroalgae (WP/MA) ratio. The F/I ratios checked were 0.2, 0.3 and 0.4 and the WP/MA ratios were 0:100, 25:75, 50:50, 75:25 and 100:0. The highest methane yield (386 L kg−1 VSadded) was achieved at an F/I ratio of 0.2 and a WP/MA ratio of 50:50. A biodegradability index of 0.87 obtained in this study indicates complete conversion of feedstock at an optimum C/N ratio of 26. Synergistic effect was found for WP/MA 25:75, 50:50 and 75:25 mixing ratios compared with the substrates mono-digestion.

In order to increase the methane yield from biomass, this paper investigates the mechanical pretreatment effect of a Hollander beater on the anaerobic digestion process of Pelvetia canaliculata macroalgae using a response surface methodology (RSM). Higher values on methane yield were obtained at lower F/I ratios, with an increase up to 2.5-fold at an F/I value of 0.3. A multi-objective optimization study was carried out with the aim of maximizing the methane yield while minimizing the pretreatment time. An optimum methane yield of 283 ml/gVS was obtained for 50 min pretreatment time and a ratio F/I of 0.3, which represents an increase of 45% compared to non-pretreated algae.

This paper discusses new experimental work investigating the change in pH of the electrolyte of individual cells in Lead-Acid batteries during discharge with a view to predicting cell polarity reversal and thereby pre-empting potentially catastrophic failure in batteries. The discharge tests were carried out on batteries which were classified as ‘new’ and ‘aged’ as a means of indicating their state of health. A new pH phenomenon has been recorded for the first time in this paper as evidenced by experimental results including measurement of half-cell potentials. The trends observed during the discharge tests could be used as additional means of indicating impending cell reversal in series connected lead-acid cells.

Measuring soil carbon dioxide efflux is a challenging task even when it is performed using respiration chambers. While gas samples are taken, measurement deviations become more evident according to the used chamber design especially when external disturbances occur. This paper studies the carbon dioxide concentration profiles within the top soil layers, and investigates the controlling factors affecting the process. The considered factors are diffusion, temperature and viscosity. The efflux equation is discussed and then it is linked with the soils geotechnical parameters, while a relationship between the Reynolds number within the soil and efflux is found. Emphasis on the importance of the external geometrical design considerations is shown through studying external boundary layer effects due to the chamber outer shell shape and how it interacts with blowing winds. Chamber stability on site of deployment is also of a significant importance considering external blowing winds. Internal geometrical considerations are linked with the flow turbulence within the dynamic chambers. It is highly recommended that respiration chamber designers need to work in parallel with a multidisciplinary team in order to make a chamber design that ensures the least disturbance to occur at the location of study.

Grass is being considered as a potential feedstock for biogas production, due to its low water consumption compared to other crops, and the fact that it can be cultivated in non-arable lands, avoiding the direct competition with food crops. However, biogas production is limited by the characteristics of the feedstock; in particular its complex lignocellulosic structure. Hence, different pretreatment methods are being investigated for grass structure disruption before undergoing the anaerobic digestion process. The aim of this paper is to review current knowledge on pretreatment techniques used for grassland biomass. Pretreatment techniques were categorized into mechanical, microwave, thermal, chemical and biological groups. The effect of the application of each studied methods on the biogas yield and on the energy balance is discussed. A further comparison between the covered techniques was revealed.

European Commission has set clear targets for 2020 regarding energy and environment policy; these targets include 20% cut in greenhouse gas emissions against the 1990 levels. It is believed that adopted strategy has encouraged the renewable energy applications during the last two decades. Moreover, measurement deviations of carbon dioxide flux occurring in respiration chambers has been seen of a great importance to explain the biochemical parameters affecting the climate change issue. This is attributed on many occasions to chamber design constraints and the way they are coupled with the studied site location. This is illustrated by external disturbances whereby when they happen while gas measurements are taken measurement deviations become more evident. This paper surveys the different soil physical, biological and geotechnical parameters and links them to meteorological ones. Consequently it explores their direct and indirect effects to the produced soil efflux. Furthermore this paper proposes several soil temperature models according to the studied case constraints to see what affects soil efflux production. Moreover a clear understanding of what affects the measurement process was achieved through surveying all the internal and external pressure parameters and how they influence the chamber in relation to time. The conclusion is that respiration chamber designers need to preserve chamber internal temperature and pressure to be equal to the outer atmosphere for the case of stabile external conditions. For the case of unstable external conditions design counter measures are incorporated. Furthermore the appropriate gas sensor needs to be selected professionally with emphasis on the importance of installation location inside the chamber. Likewise soil bacterial type and soil temperature also has an influence on efflux production.

The demand for clean power source which can be used to run the various types of vehicles on the road is increasing on a daily basis due to the fact that high emissions released from internal combustion engine play a significant role in air pollution and climate change. Fuel cell devices, particularly Proton Exchange Membrane (PEM) type, are strong candidates to replace the internal combustion engines in the transport industry. The PEMFC technology still has many challenges including high cost, low durability and hydrogen storage problems which limit the wide-world commercialization of this technology. In this paper, the fuel cell cost, durability and performances challenges which are associated with using of fuel cell technology for transport applications are detailed and reviewed. Recent developments that deal with the proposed challenges are reported. Furthermore, problems of hydrogen infrastructure and hydrogen storage in the fuel cell vehicle are discussed.

The reliance on fossil fuels is one of the most challenging problems that need to be dealt with vigorously in recent times. This is because using them is not sustainable and leads to serious environmental issues, such as: air pollution and global warming. This condition affects economic security and development. An alternative to fossil fuel is highly possible which will be more environmentally friendly, sustainable and efficient as well. Among all the different technologies associated with renewable energy, fuel cell technologies represent one of the most promising technological advancement to curb the situation. In this paper, an overview of the technology and its advantages and disadvantages compared with competitive technologies was revealed. The application of different fuel cell types in the stationary and portable sectors was covered. Furthermore, recent challenges and promising developments of current fuel cell technologies in different studied applications were reviewed. Some possible solutions to the challenges were named in this paper for both the portable and stationary fuel cell applications. The paper further seeks to expose the world to the current progress made in the fuel cell industry up to date and possible areas that needs intensified research and modifications to make the fuel cell industry more vibrant and buoyant.

This article presents the data of recovered lipid from microalgae using fuzzy logic based-modelling and particle swarm optimization (PSO) algorithm. The details of fuzzy model and optimization process were discussed in our work entitled “Application of Fuzzy Modelling and Particle Swarm Optimization to Enhance Lipid Extraction from Microalgae” (Nassef et al., 2019) [1]. The presented data are divided into two main parts. The first part represents the percentage of recovered lipid using fuzzy logic model and ANOVA. However, the second part shows the variation of the cost function (recovered lipid) for the 100 runs of PSO algorithm during optimization process. These data sets can be used as references to analyze the data obtained by any other optimization technique. The data sets are provided in the supplementary materials in Tables 1–2 .

Cell disruption is an integral part of microalga production process, which improves the release of intracellular products that are essential for biofuel production. In this work, pre-treatment parameters that will enhance the efficiency of lipid production using high-pressure homogenizer on microalgae biomass will be investigated. The high-pressure homogenizer that is considered is a GYB40-10S/GY60-6S; with a pre-treatment pressure of 1000 psi, 2000 psi, and 3000 psi, the number of passes; 1, 2, and 3, a reaction time of 3, 3.5, and 4 h. Pressure and cavitation increase the efficiency of the pre-treatment process of the homogenizer. In addition, homogenization shear force and pressure are the basic significant factors that enhance the efficiency of microalgae cell rupture. Also, the use of modelling to simulate pre-treatment processes (Response Surface Methodology (RSM), Box-Behnken Designs (BBD), and design of experiment (DOE) for process optimization will be adopted in this study. The results clearly demonstrate that high-pressure homogenization pre-treatment can effectively disrupt microalga cell walls to enhance lipid recovery efficiency, with a relatively short extraction time, both that are essential for maintaining a good quality of lipids for biofuel production. A maximum of 18% lipid yields were obtained after 3 h of HPH pre-treatment at 3000 psi.

Biogas is one essential renewable energy source which can replace natural gas after its purification. Biogas is produced from different biomass materials though the anaerobic digestion process. Algae are considered as a feedstock for biogas production, which does not compete with food production and does not need large areas of arable land and fresh water resources. In order to improve the biogas production, pre-treatment techniques have been investigated to disrupt the structure of algae increasing the availability of substrates. In this paper, a review of these pre-treatment methods is presented. Pre-treatment methods are categorised into mechanical, ultrasound and micro-wave, thermal, chemical, biological and combined groups. The effect of the application of each of the studied techniques on the biogas yield and the energy balance is discussed. A comparison of the used techniques is carried out, and discussed.

Due to the global concerns on the depletion of fossil fuels and the negative effect of their use in environmental pollution and climate change, renewable energy resources are increasingly in demand. Global solar power generation has almost doubled during the last 2 years with countries, such as China, leading the way with huge investments. The first generation of solar cells are either single or multi crystalline silicon, and still have 59% market share; the second (amorphous silicon, copper indium gallium selenide, and cadmium telluride) is approaching in terms of cost and efficiency; and the third (dye sensitized solar cells, organic photovoltaic, quantum dots, and perovskite) all show promise yet are still to come to market. However, future solar cells (using copper oxide and zinc oxide) featuring the regular intrusion of one junction layer into the other in order to massively improve junction contact area are of particular promise.

In the anaerobic digestion of lignocellulosic materials such as waste paper, the accessibility of microorganisms to the fermentable sugars is restricted by their complex structure. A mechanical pretreatment with a Hollander beater was assessed in order to reduce the biomass particle size and to increase the feedstock’ specific surface area available to the microorganisms, and therefore improve the biogas yield. Pretreatment of paper waste for 60 min improves the methane yield by 21%, from a value of 210 ml/gVS corresponding to untreated paper waste to 254 ml/gVS. 30 min pretreatment have no significant effect on the methane yield. A response surface methodology was used to evaluate the effect of the beating time and feedstock/inoculum ratio on the methane yield. An optimum methane yield of 253 ml/gVS was achieved at 55 min of beating pretreatment and a F/I ratio of 0.3.

Tube hydroforming is one of the most popular unconventional metal forming processes which is widely used to form various tubular components. By this process, tubes are formed into different shapes using internal pressure and axial compressive loads simultaneously to force a tubular blank to conform to the shape of a given die cavity. In this paper, an overall review of developments in the tube hydroforming study is presented so that other researchers at different parts of the world can use it for further investigations in this area. Initially, analytical studies which predict the sufficient parameters in tube hydroforming process were summarized. Afterwards, a guideline for employing finite element modeling (FEM) in the process analysis was proposed. Factors affecting the output of the process were addressed by many studies which were categorized and reviewed in the present work. Moreover, common types of failure of the process were introduced and improvements to avoid them were mentioned. Furthermore, different optimization algorithms to choose the input parameters that would produce the desired hydroformed component were outlined.

In the last years many researchers were concentrating to develop and design new unconventional metal forming processes. Among such new technologies, tube hydroforming was proved as one of the most promising. Geometry of the tube and die were found to have significant effects on the hydroformed part. In this work, Response surface method was used based on data provided by Finite element modeling to construct a model for the bulge height as a function of geometrical factors for T-type bi-layered tube hydroforming. Interaction effects were analyzed and discussed.

Tube hydroforming (THF) is a type of unconventional metal forming process in which high fluid pressure and axial feed are used to deform a tube blank in the desired shape. Bi-layered tube hydroforming is suitable to produce bi-layered joints to be used in special applications such as aerospace, oil production and nuclear power plants. In this work, a finite element study along with response surface methodology (RSM) for design of experiment (DOE) has been used to construct models for three responses namely: bulge height, thickness reduction, and wrinkle height as a function of geometrical factors for X shape bi-layered tube hydroforming. A finite element model was built and experimentally validated. The models developed using finite element analysis (FEA) and RSM was found to be educated. The factors effect and their interactions on the three responses were determined and discussed. Such integration was proved to be a successful technique that can be used to predict the geometry of the hydroformed part.

Many authorities have reached the conclusion that using fossil fuels, as the main source of energy to satisfy the increasing global energy demand, is ultimately unsustainable. This is because of depleting resources, and also because, if this approach is followed, emissions of carbon dioxide would continue to build up. Thus, renewable energy, including biomass has been accepted as a new energy source for sustainable development in the world. In this paper, organic material components used in the biomass to store energy were analysed. Technologies used in conversion of biomass into energy were specified. Biomass resources including woody biomass, herbaceous biomass, livestock manure, and algae were explored. For each biomass resource, the biomass structure, organic material components, technologies used in conversion of the material into energy were explained. Analysing the organic material components for each biomass material was found indispensable in order to predict and later to optimize the biomass energy resulted.

The objective of this chapter is to give an essential presentation on the theory and practice of implementing modeling and optimization techniques to evaluate different manufacturing process for a wide range of materials. This chapter includes comprehensive research works on the Design of Experiments (DoE), and the Artificial Neural Network (ANN) that is widely used to develop a mathematical relationship between the process input parameters and the output.

There is an increasing demand for the development of renewable energy system in the world to help cut CO 2 emissions and meet renewable targets set-out for 2020. Among all the different type of emerging technologies, fuel cells represent one of the most promising ones and, in particular, Proton Exchange Membrane Fuel Cells have are considered one of the most promising options for the future of the transportation applications, especially Light-Duty Electric Vehicles. Despite all the advantages, one of the most important barriers for their commercialization is their expensiveness, because they have still not reached the mature stage of their development, and only in the last years some companies started to produce fuel cell electric vehicles for the transportation market. In this paper a walk along the last 15 years has been made, and all the estimations of the PEMFC stack and systems made by different companies from 1998 until 2014 have been summarized and compared, to understand the trend of the PEMFC cost in these years, and the main contributor to the overall cost of the PEMFC stack to find out the future possible developments in order to meet the 2017 DOE target of 15 $ kW -1 for the stack and 30 $ kW -1 for the system.

The reliance upon fossil fuels is one of the most important problems that we have to deal with nowadays, because using them is highly not sustainable, and leads to serious environmental issues, such as air pollution and global warming, beside its negative effect on the economic security and development. Alternatively, environmental-friendly, sustainable, efficient new power sources are needed. Among all of the different technologies associated with the renewable energy, fuel cell technologies represent one of the most promising ones. In this article, an overview of the technology and its advantages and disadvantages compared with competitive technologies was revealed. Application of different types of fuel cells is covered in the stationary, portable and transport power sectors. Furthermore, a special focus was made on the proton exchange membrane (PEM) fuel cells; in that its structure was studied in detail. The current limitation and promising development in PEM technology were stated.

Many authorities have reached the conclusion that using fossil fuels, as the main source of energy to satisfy the increasing global energy demand, is ultimately unsustainable. This is because of depleting resources, and also because, if this approach is followed, emissions of carbon dioxide would continue to build up. Consequently, research on biofuel, that is fuel made from biomass, derived from materials that were recently living, has attracted attention. In this context, the generation of biofuels from algae shows promise for the following reasons. The algae can be grown quickly, all the materials produced are non-toxic and biodegradable, and during this growth there is an opportunity to cause greenhouse gas fixation. Also, since growing algae does not need arable land, it can be grown without competing with food or feed crops, the fuel derived from it being a “third generation” biofuel. This paper describes different types of algae (microalgae and seaweeds), and presents different technologies employed in making biofuels (biogas and biodiesel) from them.