Green Energy Solutions Research Articles

Electricity situation and potential development in Nigeria using off-grid green energy solutions

Sustainable supply of electricity is crucial to comfortable living in homes and attaining economic development in any country. Despite being blessed with enormous green and non-green energy resources, Nigeria has been in a quandary about adequate generation and supply of electricity. The electricity crisis has, over the years, had significant adverse impact on the nation’s socio-economic and technological development as well as standard of living of its citizens. This paper examines the problems in the electricity sector and the energy potential of green energy resources in Nigeria. The study reveals that the major source of electricity generation (natural gas) and mode of electricity transmission (a single national grid) in the country have been and are still being constrained by myriad of challenges, hence, the inability of the power sector to satisfy the electricity yearnings of Nigerians till date. The study also reveals that about 1182.375GWh of energy per day could be obtained from green energy resources in Nigeria and the provision of this quantity of energy through decentralized off-grid energy solutions would significantly increase electricity availability as well as accessibility in the country. Keywords: Electricity availability; Electricity crisis; Green electricity; Off-grid electricity

A Review on Challenges and Expected Solutions for Green Communication

Wireless communication is growing day by day to satisfy the need for voice and high data speed from the industry and users. To meet this demand we are upgrading communication system to 5G networks. This new technology has raised the demand of high data rate with voice and Quality of service (QoS) of signal parameters. These all also leads to the requirement of energy requirements. This high requirements also creates many issues related to human health and environment congestions. This paper is addressing the issue and challenges related to energy consumption, challenges in the development of low energy network, green energy concept in every parameter of 5G communication. We need to make a way to maintain demand and supply ration with green energy in all aspects. Here in this paper survey is done for the energy and resource relevant parameter and techniques for various domain like spectrum allocation and sharing, network density at different level, antenna designs, Internet of things (IoT) future applications, cell traffic, hardware solutions, resource allocations, energy harvesting and transfer, deployment and planning. In this paper, we address the effect of high energy requirement in upcoming 5G technology, the effect of high energy and power on the environment, green energy solution on different parameters and designs.

Sustainable energy solutions for the Aegean Archipelago Islands: What is the public attitude?

In contributing towards the realisation of plans to transform the Aegean into a “green” archipelago, the internationally acclaimed TILOS research consortium seeks to transfer tacit knowledge of smart micro-grids beyond the island of Tilos. However, research on public acceptability of sustainable energy technologies suggests that local opposition might undermine such plans. In order to minimize the problems of technological transfers it is, thus, imperative to embark on an early-stage exploration of public attitudes towards proposed interventions. In this paper, we draw on survey data from across the Aegean to uncover the widespread acceptability of green energy solutions. Simultaneously, though, we uncover how broad acceptability does not always translate into actual acceptance of the TILOS energy model, especially with respect to solutions that affect the end-user. In turn, we argue that these findings should inform future interventions with the ultimate aim of securing public support to “green” the Aegean.

Dual-phase molybdenum nitride nanorambutans for solar steam generation under one sun illumination

Water evaporation and steam production have been recognized to be considerably crucial due to the vast applications, ranging from waste water treatment, water purification, to alternative green energy solutions by water splitting, catalysis, and in-door heating. Albeit the big variety of photothermal conversion materials (PCMs) developed for this purpose, certain drawbacks, e.g. high cost, complicated synthesis, weak/narrow absorbance, bulkiness, and low evaporation rate, have hindered the application potential. Herein, we report the dual-phase molybdenum nitride nanorambutans, synthesized by a facile method, for solar steam generation. Not only the inherent properties, including strong full-spectrum absorbance, high-efficiency photothermal conversion, and super-hydrophilicity, benefit their water evaporation performance, the interconnected open mesopores of the nanorambutans further boost their capability of light harvesting and water/vapor transportation. Solar energy conversion efficiency of ∼97% under one sun together with excellent cycling stability has been demonstrated. In the desalination systems, integrating with the high salt rejection rate, the nanorambutans film can produce a water evaporation rate as high as ∼1.70 kg m−2 h−1 with an efficiency of ∼98%. Besides its compact size, the record-breaking water evaporation performance of these nanorambutans has exceeded the previous best inorganic PCM. This work introduces molybdenum nitride as a new PCM for efficient solar steam generation and all applications that can benefit from highly localized heating from nano to macro scale.

Electrical, structural, and topographical properties of direct current (DC) sputtered bilayer molybdenum thin films

Renewable energy sources offer a viable green energy solution to the increasing global energy demands, and the photovoltaics offers a means of tapping into the abundance of the solar energy. Molybdenum (Mo) thin film has been used as a back-contact electrode in high-efficiency solar cells mainly due to its ohmic nature with the absorber material (especially with chalcopyrites and kesterites), low resistivity, adequate reflectance, and porosity to alkali materials. Mo thin films used in solar cells are deposited by direct current (DC) sputtering under argon ion atmosphere. The present work deals with the effects of the sputtering deposition conditions (i.e., working pressure and power) on the electrical properties of Mo thin films deposited on soda-lime glass using DC magnetron sputtering at different working pressures (5–20 mTorr) and deposition powers (100–800 W). Optimized deposition power and sputtering pressure were used to deposit a Mo bilayer thin film intended for solar cells application. X-ray diffractometric studies showed the (110) plane corresponding to the body-centered cubic structure of the Mo material. Calculated values were used to estimate other parameters of the deposited films (e.g., stress, dislocation density), as these properties affect the potential diffusion of sodium (Na) through the soda-lime glass into the absorber layer that is important as the moderate inclusion of Na improves the cell efficiency. The cross-section of the deposited film was analyzed using a field-emission scanning electron microscopy, to confirm the successful deposition of the bilayer. The surface of the films plays a vital role in the Mo interface with the absorber layer. Atomic force microscopy was used to acquire the topographical information from the sputtered bilayer film. The resistivity, as measured using a four-point probe, of the Mo films deposited at different conditions was in the order of 10−6 Ω m while the resistivity of the bilayer was 0.60 × 10−6 Ω m.

Numerical Investigation of the Physical Properties Effect on the Thermal Performance of a Vertical Geothermal Heat Exchanger

Low-temperature geothermal energy is a promising technique for heating and cooling residential and commercial premises, especially since it is one of the green energy solutions that respect the environment. The principle of this technique is based on thermal exchange between the heat pump and the basement using a vertically buried heat exchanger. This is usually made of a U-shaped tube inserted vertically in a borehole made in the ground and filled with a filler material. The purpose of the present study is to vary the different construction materials of the U-tube, the filling material and the soil, in order to obtain the most energy-efficient parameters. The evolution of temperature and heat flux as a function of time has been highlighted for different combinations. Knowing that an experimental study requires a considerable monetary fund, the present model has been validated using previously literature results. Recommendations on the choice of different materials of the geothermal heat exchanger are proclaimed at the end of this work.

Development of Functionalized "UiO-66 MOF" Embedded Cellulose Nanocomposites for Photoelectrochemical Water Splitting

Economic distress resulting from global dependence on diminishing fossil fuels that adversely impact the environment has led to increased interest in alternative green energy technologies. The photoelectrochemical cell (PEC), provides an attractive green energy solution that incorporates semiconductor materials capable of absorbing visible light to power the splitting of water and create H2 gas, a clean fuel source. PEC systems today, however, are not yet commercially viable due to a lack in efficiency, stability and cost effectiveness. Therefore, the goal of this work is to create a novel, low price semiconducting material to be used as an electrode in a PEC system. This will be accomplished by incorporating the zirconium based Metal Organic Framework (MOF) UiO-66 into a celllulostic network to create a flexible, semiconducting material. The UiO-66 MOF offers a combination of defect sites on the Zr metal cluster and an aromatic linker allowing for light absorption coupled with efficient charge transport. Unfortunately, UiO-66 absorbs in the UV region (2% of sunlight), but its high stability and conjugated organic ligands make it ideal for photosensitization. Simple post synthetic modifications (PSM) can be done to improve light harvesting and electron transport capabilities within the cellulose network. Modifications incorporated in this work include the use of polyaniline crosslinkers as well as metal nanoparticle doping. Conductivity of each material was characterized using a four point probe and measuring current response to applied stepwise voltage. PEC performance was determined by illuminating cell with light and measuring voltage, current and product evolution. Overall, this work provides a foundational design of low cost working electrodes for use in PEC systems, that can lead to future modifications to optimize cell performance.

Effect of working fluid on the performance of the duplex Stirling refrigerator

Abstract Duplex Stirling refrigerator is one of the best alternative systems for providing green and clean energy solutions. It consists of Stirling refrigerator and Stirling heat engine in a back to back configuration. The main constraint of the duplex system is the work equality between the supplied one by the heat engine and the consumed one by the refrigerator. In this study, the overall performance and the design of the duplex Stirling refrigerator are examined analytically for different couples of working fluids and the refrigerants. Helium, hydrogen and carbon dioxide are selected as the coolant and working fluid for the duplex system which leads a nine different fluid couples investigated in the present study. The compatibility of these refrigerants and working fluids are examined by observing the high overall performances of the duplex Stirling refrigerator. In order to figure out the fluid couple which maintains the highest performance, nine different couple paired among the given gasses are evaluated. As regard to the obtained results, not only the couples which provide both higher cooling performances at the refrigerator and the better efficiency at the heat engine are identified but also the right design parameters which could achieve these higher performances are determined. The outcomes of the study would be very helpful for the designers in practice since the results are presented in a wide spectrum by the diagrams.

Solar Cooling – A Green Energy Solution for Reducing Food Losses

According to the recent reports of the Food and Agriculture Organization (FAO) of the United Nations, roughly one third of the food produced in the world for human consumption every year get lost or wasted globally, while 800 million people are going into hungry. Saving ¼ of the food which is been wasted will provide the opportunity to feed this 800 million people. Food waste refers in to throwing perfectly edible food into trash at the consumption level while food loss refers to the losses which occur along the food chain that is at the production, harvesting, post-harvest activities and processing phases. Poor handling transport, storage facilities and lack of correct infrastructure cause post-harvest food losses in developing countries. Fresh products like fruits, vegetables, meat and fish straight from the farm or after the harvest can be spoilt in hot climates due to lack of infrastructure for correct transportation, storage, cooling and marketing. Sri Lankan scenario is not much different to the rest of the world where there is about 10-40% loss in fruits and vegetables within food supply chain. There are no country wide valid estimates of looses among other food commodities. Sri Lanka located close to the equator, receives an abundant supply of solar radiation throughout the year. Solar radiation over the island does not show a marked seasonal variation. Due to these reasons, solar cooling is a promising technology to address reducing food losses in Sri Lanka. Solar cooling technology can be applied for food preservation by using it to generate ice or for refrigeration. Different types of ice (blocks or flakes) are typically used to keep fish or milk within the conservation temperature range. These types of ice making facilities are globally available and managed by a community or a cooperative. Solar refrigerators are used for the purpose of conserving fruits and vegetables which operates at a temperature below 100 C. There are many solar refrigeration technologies available such as well known solar photovoltaic systems, solar absorption systems and, solar adsorption systems. Each of these technologies have their own advantages and limitations and most of these technologies are still at the developing stage. There is a global trend towards harnessing solar energy for food preservation and this will be a promising technology to reduce food losses in Sri Lanka. Keywords: Solar cooling, Solar refrigeration, Food losses

Green energy for the battlefield

ABSTRACTPopulation of the world is growing with increasing rate and it seems that existing fossil fuel energy sources will not be able to meet energy demand in the near future. Energy is not only crucial for civil sector but also it is one of the most important assets in defense sector. Energy for military operations is mostly provided from fossil fuel as it is the case in other sectors; however, fossil fuels have hazardous effects to the environment and cause global environment concerns. These drawbacks of fossil fuels are also valid for battlefield. Furthermore, transportation of fossil fuels causes extra safety and logistics problems in military case. In this study, we developed a hybrid green energy solution with wind, solar, and batteries together to minimize or eliminate the fossil fuel demand for the battlefield. Results of our algorithm are superior to the already used diesel generator solution from the point of view of cost and various other aspects. The novelty of our study stems from applying optimization of hybrid green energy solution to military case with battlefield constraints.

Review on Recent Advances in Titanium Dye Oxide Nanoparticles for Dye Sensitized Solar Cell Applications

<p>Alternate energy source becomes a crucial for green energy solution against ever increasing demand. Dye Sensitized solar cell is another promising option toward green energy providing opportunity to explore natural dye extracts from plants. This review explores recent developments in the field of Dye Sensitized solar cell technology specifically with sensitizer synthesized from plants which are also found in India. Anthocyanin, betalain, chlorophyll and carotenoids are among the most common plant pigments explored as sensitizers. The review of different attempts on fabrication of natural dye based solar cells implies that titanium dioxide (TiO<sub>2</sub>) nano particles can be used as photoanode, platinum (Pt) as counter electrode and iodine/iodide electrolyte. Plant pigments are highly pH sensitive and can alter solar cell performance based on its extraction method, concentration and its ability to anchor with photoanode. Stability of dye, absorption in near IR range and leakage of liquid electrolyte are few of the challenges ahead. However, natural dye is biodegradable and non-toxic having most of the extraction process harmless to environment. In addition, natural dye has the promising future as it is abundant. </p>

European cities test green energy and transport solutions

European cities test green energy and transport solutions

Concentrated Photo Voltaics (CPV): a case study

Concentrated PhotoVoltaic (CPV), among green energy solutions, nowadays has the ambition to reach grid-parity without subside. CPV substitutes large areas of expensive semiconductor solar cells, with concentrating optics made of cheap materials. Moreover the cells that are suitable for CPV exhibits an unprecedented efficiency and their technology is progressing every year. A case study project, TwinFocus® , will be presented in detail.

Characterization of Nano‐Titania Modified CdS /Polysulfide Electrolyte Interface by Utilizing MottSchottky and Electrochemical Impedance Spectroscopy

AbstractPhotoelectrochemical (PEC) H2 generation is a green energy solution to upcoming energy crises. We have modified photo‐unstable CdS thin film with TiO2‐nanoparticles. Semiconductor electrolyte interface (SEI) of modified CdS surface using MottSchottky (MS) analysis is used to evaluate the relative band edge positions and flat‐band potential (VFB). Effect of applied AC‐frequency, electrolyte pH and electrode surface modification, on VFB and carrier‐concentration is studied. Modified photoanode shows high photocurrent and stability, than bare CdS photoanode. Improved performance of modified photoanode is attributed to the higher recombination lifetime of the charge carrier as deduced by electrochemical impedance spectroscopy.

Nuclear Enhanced MEM Used to Analyze Local Distortions in Lead Chalcogenides

We introduce a novel method for reconstructing nuclear density distributions (NDDs): Nuclear Enhanced X-ray Maximum Entropy Method (NEXMEM). NEXMEM offers an alternative route to experimental NDDs, exploiting the superior quality of synchrotron X-ray data compared to neutron data. The method was conceived to analyse local distortions in the thermoelectric lead chalcogenides, PbX (X = S, Se, Te). Thermoelectric materials are functional materials with the unique ability to interconvert heat and electricity, holding much promise for green energy solutions such as waste heat recovery. The extraordinary thermoelectric performance of binary lead chalcogenides has caused huge research activity, but the mechanisms governing their unexpected low thermal conductivity still remain a controversial topic. It has been proposed to result from giant anharmonic phonon scattering or from local fluctuating dipoles on the Pb site.[1,2] No macroscopic symmetry change are associated with these effects, rendering them invisible to conventional crystallographic techniques. For this reason PbX was until recently believed to adopt the ideal, undistorted rock-salt structure. In the present study, we investigate PbX using multi-temperature synchrotron powder X-ray diffraction data in combination with the maximum entropy method (MEM) and NEXMEM. In addition NEXMEM has been validated by testing against simulated powder diffraction data of PbTe with known displacements of Pb. The increased resolution of NEXMEM proved essential for resolving Pb-displacement of 0.2 Å in simulated data. The figure below shows Pb in the (100) plane for MEM, NEXMEM and the actual NDD of the test structure. Our findings outline the extent of disorder in lead chalcogenides, promoting our understanding of this class of high-performance thermoelectric materials. Furthermore we introduce NEXMEM which can be used for widespread characterization of subtle atomic features in crystals with unusual properties.

Characterization of Local Distortions in Thermoelectric Lead Chalcogenides

Thermoelectric materials are functional materials with the unique ability to interconvert heat and electricity, holding much promise for green energy solutions such as efficient waste heat recovery. The extraordinary thermoelectric performance of binary lead chalcogenides has caused huge research activity, but the mechanisms governing their unexpected low thermal conductivity still remain a controversial topic. It has been proposed to result from giant anharmonic phonon scattering or from local fluctuating dipoles on the Pb site, emerging with temperature on the Pb site.[1,2] No macroscopic symmetry change are associated with these effects, rendering them invisible to conventional crystallographic techniques. For this reason lead chalcogenides were until recently believed to adopt the ideal, undistorted rock-salt structure. In the present study, we probe the peculiar structural features in PbX (X = S, Se, Te) using multi-temperature synchrotron powder X-ray diffraction data in combination with the maximum entropy method. Distorted atoms are detected and quantified by refinement of anharmonic probability density functions. The charge density analysis is complemented by nuclear density distributions (NDDs) reconstructed from neutron diffraction data and by a novel method: Nuclear Enhanced X-ray Maximum Entropy Method (NEXMEM). NEXMEM offers an alternative route to experimental NDDs, exploiting the superior quality of synchrotron X-ray data compared to neutron diffraction data. The increased atomic resolution introduced by NEXMEM proved essential for resolving atomic distortions, see figure below showing Pb in the (100) plane. Our findings outline the extent of disorder and anharmonicity in binary lead chalcogenides, promoting our fundamental understanding of this class of high-performance thermoelectric materials. The applied approach can be used in general, opening up for widespread characterization of subtle features in crystals with unusual properties.

A review of thermoelectrics research – Recent developments and potentials for sustainable and renewable energy applications

Abstract In recent years, thermoelectric (TE) devices have emerged as promising alternative environmental friendly applications for heat pumps and power generators since the environmental issues such as the global warming and the limitations of energy resources gradually drew worldwide attentions. Due to the green feature and distinct advantages, the thermoelectric technology have been applied to different areas in an effort of designing simple, compact and environmental friendly systems. The applied areas are extended from the earliest application on kerosene lamp to aerospace applications, transportation tools, industrial utilities, medical services, electronic devices and temperature detecting and measuring facilities. The application potentials of TE in directly conversing thermal energy into electrical power have been identified, especially for where the cost of thermal energy input need not to be considered, such as waste heat utilization, in the light of the present low efficiency of thermoelectric conversion. The capability of TE in producing thermal energy (in terms of cooling or heating) with the use of electrical power is also well identified. This paper reviews the status of the material development and thermoelectric applications in different areas and discusses the difficulties in terms of the commercialisations of advanced materials. Other than this, the main purpose of this paper is to present the great potential of achieving both environmental and economic benefits by exclusively utilizing thermoelectric applications in different areas. It also comes to the conclusion that the thermoelectric applications with the current conversion efficiency are economically and technically practical for micro/small applications. However, it would be transformed to a more significant green energy solution for improving the current environment and energy issues by using medium/large scale thermoelectric applications when the thermoelectric materials with a figure-of-merit over 2 come into commercial practice.

Performance analysis of a co-generation system using solar energy and SOFC technology

Due to the increasing future energy demands and global warming, the renewable alternative energy sources and the efficient power systems have been getting importance over the last few decades. Among the renewable energy technologies, the solar energy coupling with fuel cell technology will be the promising possibilities for the future green energy solutions. Fuel cell cogeneration is an auspicious technology that can potentially reduce the energy consumption and environmental impact associated with serving building electrical and thermal demands. In this study, performance assessment of a co-generation system is presented to deliver electrical and thermal energy using the solar energy and the reversible solid oxide fuel cell. A mathematical model of the co-generation system is developed. To illustrate the performance, the system is considered in three operation modes: a solar-solid oxide fuel cell (SOFC) mode, which is low solar radiation time when the solar photovoltaic (PV) and SOFC are used for electric and heat load supply; a solar-solid oxide steam electrolyzer (SOSE) mode, which is high solar radiation time when PV is used for power supply to the electrical load and to the steam electrolyzer to generate hydrogen (H2); and a SOFC mode, which is the power and heat generation mode of reversible SOFC using the storage H2 at night time. Also the effects of solar radiation on the system performances and the effects of temperature on RSOFC are analyzed. In this study, 100kW electric loads are considered and analyzed for the power and heat generation in those three modes to evaluate the performances of the system. This study is also revealed the combined heat and power (CHP) efficiency of the system. The overall system efficiency achieved for the solar-SOFC mode is 23%, for the solar-SOSE mode is 20% and for the SOFC mode is 83.6%. Besides, the only electricity generation efficiency for the solar-SOFC mode is 15%, for the solar-SOSE mode is 14% and for the SOFC mode is 44.28%. An economic analysis is presented based on the annual electricity generation from the system and the system has shown the good economic viability in this study with a unit cost of energy (COE) about 0.068$/kWh.

Application of Solar Energy and Reversible Solid Oxide Fuel Cell in a Co-Generation System

 Abstract—The sustainable energy sources have been concentrated over the last few decades. The solar energy and solid oxide fuel (SOFC) technology will be the promising possibility to tackle the energy poverty and environment pollution. Hence, the solar energy coupling with fuel cell technology can be a green energy solution for the next generation. In this study, a co-generation system is presented using the solar energy and reversible solid oxide fuel cell (RSOFC). The solar energy is used for power supply and steam electrolysis and the solid oxide fuel cell is used for hydrogen production from steam electrolysis as well as electricity and heat from generated hydrogen fuel (H2).

Thermal Transport across Solid Interfaces with Nanoscale Imperfections: Effects of Roughness, Disorder, Dislocations, and Bonding on Thermal Boundary Conductance

The efficiency in modern technologies and green energy solutions has boiled down to a thermal engineering problem on the nanoscale. Due to the magnitudes of the thermal mean free paths approaching or overpassing typical length scales in nanomaterials (i.e., materials with length scales less than one micrometer), the thermal transport across interfaces can dictate the overall thermal resistance in nanosystems. However, the fundamental mechanisms driving these electron and phonon interactions at nanoscale interfaces are difficult to predict and control since the thermal boundary conductance across interfaces is intimately related to the characteristics of the interface (structure, bonding, geometry, etc.) in addition to the fundamental atomistic properties of the materials comprising the interface itself. In this paper, I review the recent experimental progress in understanding the interplay between interfacial properties on the atomic scale and thermal transport across solid interfaces. I focus this discussion specifically on the role of interfacial nanoscale “imperfections,” such as surface roughness, compositional disorder, atomic dislocations, or interfacial bonding. Each type of interfacial imperfection leads to different scattering mechanisms that can be used to control the thermal boundary conductance. This offers a unique avenue for controlling scattering and thermal transport in nanotechnology.