Efficient Renewable Energy Sources Research Articles

Constructing a Novel Surfactant-free MoS2 Nanosheet Modified MgIn2S4 Marigold Microflower: An Efficient Visible-Light Driven 2D-2D p-n Heterojunction Photocatalyst toward HER and pH Regulated NRR

Nowadays the major research objective is to find an efficient renewable energy source which can be a potential solution to all our ongoing problems. With this regard, the interest has been blossomi...

Analisis Kecekapan Aktiviti Penyelidikan dan Pembangunan (R&D) dalam Sektor Tenaga Boleh Diperbaharui di Malaysia

Research and development (R&D) activities in the renewable energy sector are one of the key elements under the National Renewable Energy Action Plan (NREPAP). However, renewable energy R&D activities are not considered as one of the key components of the country’s R&D program and it needs to compete with other fields to get the research funding. Although the renewable energy R&D fund received is relatively low, the output from the renewable energy R&D activities in Malaysia is seen as encouraging especially on the research publication, patent, and development of human capital. This means that the R&D activities undertaken contribute indirectly to the development of renewable energy in Malaysia. The purpose of this study was to evaluate the performance of R&D activities in Malaysia based on five renewable energy sources, namely solar, wind, biomass, biogas, and mini hydro using the data envelopment analysis (DEA) approach from 2012 to 2017. This study used an output-oriented Charnes, Cooper, Rhodes (CCR)–DEA model with the ratio of one output and four inputs. The result of this study indicates that biomass is the most efficient renewable energy resource, while the wind is the least efficient renewable energy source from the perspective of R&D activities in Malaysia. The overall performance of renewable energy R&D activities in Malaysia is good with a score of 69.2% in 2012-2017. The results of this study are in line with the Malaysia Government's desire to develop biomass energy resources, as stated in the National Biomass Strategy 2020 initiative. The results of this study can serve as the basis for developing specific policies or strategies to strengthen R&Dactivities further to support the development of renewable energy in Malaysia.

Torrefied materials derived from waste vegetable biomass

Torrefied materials produced from agricultural waste is regarded as one of the most efficient renewable energy source. By recycling the waste materials through optimized torrefaction process, coal like material can be produced. The raw materials are heated up in a sealed, oxygenless environment at 300 °C. At this temperature, many of the volatiles in the material begin to decompose and part of the sappy lignin that binds the material together breaks down and vaporizes. This study focuses on exploring to convert agricultural waste to torrefied material, the biocoal through fast and slow conversion process. The waste vegetable biomass material selected for this study were waste cauliflower, lettuce and coriander. Proximate, ultimate and TGA analysis were done after drying and pulverizing the material. The powdered samples were pelleted and their calorific values and yield were recorded. Torrefaction was conducted under 300 °C for a given residence time at a fast and slow heating rate. The torrefied material, especially from coriander residue gave the highest yield and calorific value under slow torrefaction process of 46.6% and 16.45 MJ/kg respectively. The high carbon content in biocoal makes potential coal substitute for use in thermal conversion systems. The material is densified after torrefication, the remaining lignin in the product, requires no binding agent to make the pellets, briquettes and bricks for co-firing applications.

Non-contact vibration monitoring of rotating wind turbines using a semi-autonomous UAV

With the recent demands for more efficient clean renewable energy sources, wind turbines are designed that have large rotor blade diameters. These large-sized wind turbines need to be periodically monitored to prevent catastrophic failures. This paper aims to develop a practice for obtaining the vibration characteristics of wind turbine blades that can be eventually used for structural health monitoring of these structures. This monitoring technique needs to be robust and non-contact to prevent any interference with the operation of the wind turbine. In this work, a digital image correlation (DIC) system installed on a drone is used as a sensing technique to obtain the dynamic characteristics of rotating wind turbine blades. The DIC uses a stereo-camera system to record the deflections of the blades and provides non-contact measurements. The unmanned aerial vehicle (UAV) enables on-site robust measurements. Furthermore, a dynamic stitching technique is used after DIC measurement to obtain vibration characteristics of the entire blade with high accuracy. The proposed health monitoring technique can be used by engineers for remote structural health monitoring of wind turbines during operation in both offshore and inland wind farms.

Disaggregated renewable energy consumption and environmental pollution nexus in G-7 countries

Although it is widely accepted that renewable energy consumption is vital for environmental sustainability, the environmental effectiveness of individual renewable energy types is often overlooked. Therefore, this paper examined the multivariate relationship between disaggregated renewable energy (hydroelectricity, wind, solar and biomass) consumption, economic growth and environmental pollution for the period from 1991 to 2014 in G-7 (The Group of Seven) countries. The study used both augmented mean group estimator and panel bootstrap causality method to consider the cross-sectional dependence and country specific heterogeneity across G-7 countries. Empirical findings indicate that increasing biomass energy consumption was efficient to reduce carbon emission in France, Germany, Japan and the United States; increasing hydroelectricity usage was efficient to reduce carbon emission in Italy and the United Kingdom; wind energy consumption reduced emission in Canada and solar energy usage was efficient on reducing emission in France and Italy for observed period. Moreover, in case of panel, it is found that increasing hydroelectricity, biomass and wind energy consumption reduced carbon emissions while the impact of solar energy consumption is statistically insignificant in G-7 countries. In addition, the hydroelectricity consumption was found the most efficient renewable energy source to reduce environmental pollution for the panel of G-7 countries.

Policy-making for renewable energy sources in search of sustainable development: a hybrid DEA-FBWM approach

Energy planning is one of the most important issues affecting the behaviors and policies of different countries at national and international levels. Concerns over the depletion of non-renewable energy sources and the pollution caused by their consumption have led most countries to focus on renewable energy sources. In this regard, governments are trying to develop policies for extensive use of their renewable energy sources. The precise formulation of such policies requires the development of quantitative approaches to assess the potential of the country in this field. Because selecting inappropriate approaches for evaluating the energy resources leads to wrong decisions in planning and policy-making for the whole energy sector and can cause irrecoverable damages to the country. Since energy issues are multi-dimensional in their nature, the development and selection of the appropriate decision-making approach among the available methods have become a critical issue in this field. In order to overcome this problem, this study proposed a hybrid approach by combining data envelopment analysis (DEA) and fuzzy best–worst method (FBWM) for the prioritization of renewable energy sources (RESs) in Iran. For this purpose, it considered five technical, economic, environmental, social, and political sustainability dimensions into account. The obtained results indicated that the solar, hydroelectric, wind, biomass, and geothermal energy sources are respectively the most efficient RESs in Iran. Also, a three-stage sensitivity analysis approach has proved the consistency of DEA-FBWM approach over the other decision-making methods. Consequently, the proposed approach can be used as a reliable method in the energy policy-making process.

Development, analysis and application of a predictive controller to a small-scale district heating system

District heating and cooling networks have great potential for energy saving, efficient thermal energy distribution and renewable energy source integration. Currently, heating systems are managed on the basis of operator experience or by using adaptive controllers, however these solutions are not suitable when there are remarkable variations in boundary conditions. In this context, Model Predictive Control is a promising strategy as it optimizes control based on the prediction of the future behavior of system dynamics and disturbances by means of simplified models. This paper presents the development of a predictive controller based on a novel Dynamic Programming optimization algorithm and aimed to supply the thermal energy to entire buildings within district heating networks. The controller is exploited to operate the district heating network of a school complex in a simulation environment (i.e. Model-in-the-Loop). Each branch connected to the network is optimized by a dedicated controller according to a multi-agent strategy. The performance of the innovative controller is compared to the results obtained by using a conventional PID controller. Conservative results show that, with the innovative controller, a reduction in fuel consumption of up to more than 7% is obtained together with up to 5 h of avoided failures of the indoor comfort constraints, depending on the season. Overall, the Model-based Predictive Controller is able to fulfill comfort requirements adequately while minimizing energy consumption. Moreover, the multi-agent approach allows these results to be extended to larger networks in future studies.

Evaluating renewable energy sources for implementing the hydrogen economy in Pakistan: a two-stage fuzzy MCDM approach.

Hydrogen can play a crucial role in increasing energy security and reducing greenhouse gases in Pakistan. Hydrogen can only be a clean and sustainable fuel if it is generated from renewable energy sources (RES). Thus, it is important to evaluate viability of RES for hydrogen production. This study developed a two-stage fuzzy MCDM (Multi-criteria decision-making) approach to select the most efficient RES. In the first stage, fuzzy analytical hierarchy process (AHP) obtained the relative weights of four criteria for the selection of best RES. These criteria included commercial potential, environmental impacts, economic benefits, and social acceptance. In the second stage, data envelopment analysis (DEA) measured the relative efficiency of RES using weights of criteria as outputs, and the cost of RES-based electricity generation as input. The results indicated that wind and solar are the most efficient sources of hydrogen production in Pakistan. Municipal solid waste (MSW) and biomass can also be considered a feedstock for the hydrogen economy. Geothermal reported to be the less efficient source and thus is not recommended at present. Sensitivity analysis confirmed the robustness of results obtained using the developed framework.

Fuzzy Sliding Mode based PI Controlled UPFC for Optimized WECS Dynamics during Fault Ride Through

With the enormous global growth in electrical power demand and the associated decrease in conventional power resources, electricity generation from renewable energy sources have been furiously sought worldwide, as they represent infinite and clean natural resources. Wind energy is one of the most efficient renewable energy sources. However, due to the fluctuating behaviour of wind energy and the need of electronic devices to link wind turbine generator with existing electricity grids, problems such as frequency oscillations, voltage instability and harmonic distortion may arise. Flexible alternative current transmission system (FACTS) devices, such as unified power flow controller (UPFC), can provide technical solutions to improve the overall performance of wind energy conversion systems (WECS). This paper presents a comparative study of transient stability and reactive power compensation issues in an autonomous wind energy conversion system (WECS) using robust fuzzy-sliding mode based unified power flow controller (UPFC). It is noted from the simulation results that the performance of UPFC is superior to static VAR compensator and static synchronous compensator in improving the voltage profile of the WECS. Further, fuzzy and fuzzy-sliding mode based UPFC controller is designed in order to improve the transient performance. Simulation results reflect the robustness of the proposed fuzzy-sliding mode controller for better reactive power management to improve the voltage stability in comparison with the conventional PI and fuzzy-PI controllers. In addition to this, system stability analysis is performed based on Eigen value, bode and Popov for supporting the robustness of the proposed controller.

Assessing sustainable biogas potentials—case study for Serbia

Biogas is efficient renewable energy source concerning greenhouse gases emission (GHG) reduction and waste disposal. The most abundant biogas substrates are originating from agriculture, i.e., energy plants and wastes such as manure, and respective production and utilization can be used to support rural development. Defining sustainable potentials, i.e., realistic value under defined conditions, of biogas production in some geographical region is important, as a background for policy development on a national, regional, and even local level. The objective of the study was defying method for its assessment. The characteristics of the proposed method are as follows: (1) biogas potential is expressed in electric power of cogeneration units that can operate with biogas produced from available feedstock. Available thermal energy, or biomethane production, can be calculated based on biogas potential; (2) the determined sustainable potential is based on environmental, technological, and socio-economic criteria; (3) the assessment is related to the actual substrates’ availability, whereby expected technological advancements are considered. Developed method has been tested in the form of a case study for Serbia and obtained outcomes compared with studies previously done by other authors. The potential is lower than previously assessed. The forecasted technology advancements and reduction of specific investment costs in the future can contribute to the increase of potential, higher share of wastes and by-products in substrates. New, smaller biogas plants would be constructed in undeveloped regions, what could contribute to rural development.

Mathematical modeling of the magnetic field of a low-speed synchronous generator with permanent magnets

Increased scientific and practical interest in the development, design, research and implementation of low-speed synchronous generators with permanent magnets (SGPM) is caused by the need to completely equip various sectors of the economy with efficient renewable energy sources based on the principles of wind, hydro and pneumatic power. The impetus for the creative thinking of Russian and foreign science to create and introduce into production and operation new types of designs of magnetoelectric machines with excitation from permanent magnets was the emergence in the consumer market a wide range of available for use high-coercive permanent magnets based on rare earth elements of the alloy neodymium-iron-boron (NdFeB). In this paper we propose a design of low-speed synchronous generator with permanent magnets, taking into account the full list of requirements for renewable energy sources, accumulated in the practical experience of developing such electromechanical converters. The article presents the results of mathematical modeling of the magnetic field of low-speed synchronous generator using the package Ansoft Maxwell 16.0.

FACTORES CLAVE EN LA IMPLEMENTACIÓN DE POLÍTICAS ENERGÉTICAS EN ITALIA

Actualmente, la implementación de medidas de eficiencia energética (EE) y energías renovables (ER) se encuentra en la agenda política de numerosos países; sin embargo, el avance concreto y la implementación efectiva de dichas estrategias es aún muy dispar. Si bien existen países donde dichas tecnologías han recalado efectivamente en sus regímenes socio-técnicos; una gran mayoría aún no comenzó a enfrentar dicha transición de manera sistémica y, por consiguiente, deberán afrontar numerosos desafíos. En tal sentido, este trabajo presenta un análisis de la transición energética que se está desarrollando de forma sostenida en el sector residencial italiano desde mediados de la década del 2000 (2006-2016) a los efectos de identificar, sistematizar y extraer factores clave del caso de estudio. A partir de éstos es posible discutir acerca de la implementación de políticas energéticas y generar insumos para otros casos de estudio que pretendan impulsar medidas estatales de mejoramiento energético.

Investigation on fuel gas production from pulp and paper waste water impregnated coconut husk in fluidized bed gasifier via humidified air and CO2 gasification

The waste biomass has immense opportunities and plenty of potentials to be an efficient source of renewable energy. Initially, native unripe coconut husk (NCH) was used as raw material for fluidized bed gasification. Then NCH was treated with paper and pulp waste water to impregnate metals present in it for getting enhanced H2 yield in fuel gas. Humidified air was used as gasifying medium, which served the purpose of introducing water vapour to take part in the gasification process. Then after, gasification medium was retrofitted with CO2, which enhanced both the higher heating value (HHV), and CO and H2 content in the fuel gas. This research serves the dual benefit of energy generation and waste minimization. HHV of unripe coconut husk was investigated and found to be 20.95 MJ/kg. H2 yield and HHV from impregnated coconut husk (ICH) were obtained as 55.55 vol % and 5.24 MJ/Nm3, respectively at HER 0.1 and gasification temperature of 850 °C in case of fluidized bed gasification. The GC-MS analysis of fuel oil obtained from ICH gasification was done to get the information about high yield of fuel gas as promise product of fluidized bed gasification.

Development of a Model-based Predictive Controller for a heat distribution network

Research studies concerning heating and cooling systems have increased in recent years, pledging great potential for energy saving, efficient thermal energy distribution and renewable energy source integration. Currently, heating systems are managed on the basis of operator experience or by using adaptive controllers, however these solutions are not suitable when there are remarkable variations in boundary conditions (e.g. weather changes). In this context, Model Predictive Control is a promising strategy as it optimizes the control action based on the prediction of the future behavior of both system dynamics and disturbances by means of simplified models. This paper presents the control of a building heating system through a Model-in-the-Loop Model Predictive Control approach. A detailed model that replicates the behavior of the real system is controlled with a predictive controller based on a novel Dynamic Programming optimization algorithm implemented in Matlab®. The performance of the innovative controller is compared to the results obtained with a PID controller. Overall, the Model Predictive Control strategy is able to fulfill comfort requirements properly while minimizing energy consumption.

Efficiency Assessment of Renewable Energy Sources

A review of the methods and models used at the ESI SB RAS to assess the effectiveness of renewable energy sources (RES) was carried out. Criteria were formulated and calculation formulas were given for a preliminary assessment of the competitiveness of renewable energy sources as compared to alternative energy supply options. A mathematical model of the world energy system was considered, where renewable energy sources were described by averaged indicators. The model allows for different scenarios of external conditions to explore the prospects for the development of energy technologies, including renewable energy sources. For the analysis of autonomous energy systems with RES, a simulation model was developed so as to treat the processes of production, consumption, and energy storage in their dynamics. The optimization version of the mathematical model eliminates the need for a pre-assignment of the energy flow control algorithm. In this case, it is possible to study systems with the simultaneous presence of several units of energy storage of various types. For the study of renewable energy sources under market conditions, a model was developed so as to take into account the presence of various decision-making hubs, as well as the impact of governmental regulatory bodies in the market. It was shown that the most efficient mechanism for encouraging the development of renewable energy sources is the creation of a market for "green certificates", with the least efficient renewable energy sources to be subsidized.

Effect of molar ratio of water / ethanol on hydrogen selectivity in catalytic production of hydrogen using steam reforming of ethanol

As fossil energy resources are shrinking, the increase in global energy needs and environmental pollution paved the way to the search for new and renewable energy resources. Therefore, the future of energy technology is being built on the use of hydrogen, which is one of the cleanest and most efficient renewable energy sources, and steam reforming is becoming the utmost method to produce hydrogen. This study focuses on the operation condition of steam reforming of ethanol on catalyst materials, which were shaped using active metals such as Ni, Cu and Cs and supporting materials which were activated by carbon and LiAlO2. These catalyst materials were tested to produce hydrogen gas using different water/ethanol mole ratio at different temperatures and a constant feed flow rate. The evaluation regarding hydrogen selectivity results and the percentage of hydrogen in the products revealed that NiCuCs/LiAlO2 catalyst showed the highest performance at all water/ethanol ratios and temperatures between 300 and 600 °C.

Material and method selection for efficient solid oxide fuel cell anode: Recent advancements and reviews

The energy crisis has reached to an alarming situation due to increase in population. To overcome the shortfall of energy, solid oxide fuel cell (SOFC) being cheap, clean, and efficient renewable energy source is getting attention for electricity generation. Out of the three main components as anode, electrolyte, and cathode; anode/fuel electrode is an important component of SOFC because it allows the flow of electrons via external circuit to cathode generating the electric current and hence requires high electrical conductivity. In this review, anode materials synthesized until now are reviewed and by careful analysis categorized on the basis of operating temperature, conductivity, electrode polarization resistance, and structure. This comparison and categorization will provide selection criteria for state-of-the-art and highly efficient anode materials for SOFC. In addition, the synthesis methods have been reviewed on the basis of their pros and cons, which will further facilitate the researchers to select the best synthesis method so as to get optimized properties of materials.

Short-Term Wind Electric Power Forecasting Using a Novel Multi-Stage Intelligent Algorithm

As the most efficient renewable energy source for generating electricity in a modern electricity network, wind power has the potential to realize sustainable energy supply. However, owing to its random and intermittent instincts, a high permeability of wind power into a power network demands accurate and effective wind energy prediction models. This study proposes a multi-stage intelligent algorithm for wind electric power prediction, which combines the Beveridge–Nelson (B-N) decomposition approach, the Least Square Support Vector Machine (LSSVM), and a newly proposed intelligent optimization approach called the Grasshopper Optimization Algorithm (GOA). For data preprocessing, the B-N decomposition approach was employed to disintegrate the hourly wind electric power data into a deterministic trend, a cyclic term, and a random component. Then, the LSSVM optimized by the GOA (denoted GOA-LSSVM) was applied to forecast the future 168 h of the deterministic trend, the cyclic term, and the stochastic component, respectively. Finally, the future hourly wind electric power values can be obtained by multiplying the forecasted values of these three trends. Through comparing the forecasting performance of this proposed method with the LSSVM, the LSSVM optimized by the Fruit-fly Optimization Algorithm (FOA-LSSVM), and the LSSVM optimized by Particle Swarm Optimization (PSO-LSSVM), it is verified that the established multi-stage approach is superior to other models and can increase the precision of wind electric power prediction effectively.

Re-use of historic buildings and energy refurbishment analysis via building performance simulation: A case study

This paper analyses the possibility to apply energy refurbishment measures in restored historic buildings in order to ensure reuse. The objective of the paper is to provide an appropriate methodology for the structural restoration of historic buildings, their re-use and sustainable energy refurbishment in accordance with current needs and conservation principles. The study provides the analysis and evaluation of the realized goals regarding energy refurbishment and energy efficiency. The presented historic buildings belong to Hilandar Monastery, Mount Athos, Greece. Mount Athos has been listed in UNESCO World Heritage Site for decades. The paper deals with the expert analysis of abandoned and devastated structures included in the Haybarn Complex. This paper provides a positive outcome of the performed restoration in terms of energy refurbishment and repurpose, since these buildings were turned into unique accommodation facilities for visitors. This accomplishment can be seen as a useful recommendation for improving energy efficiency of historic buildings during their restoration. All the undertaken methods are in accordance with the environmental protection requirements. This study is a practical observation and analysis of energy refurbishment in the field of restoration of listed buildings. This certainly is the most important contribution of this paper. All energy efficiency measures and renewable energy sources were carried out in compliance with conservation requirements and visual authenticity of historic structures. Assessment and analysis of energy efficient refurbishment via building performance simulation method and energy efficiency optimization was applied to several different models of restoration that was carried out in the Haybarn Complex.

High-efficiency and stable alloyed nickel based electrodes for hydrogen evolution by seawater splitting

Hydrogen is regarded as a highly efficient and clean renewable energy source. However, the high cost of preferred platinum catalysts becomes an economic burden for its commercial applications. Therefore, the development of cost-effective and robust catalysts, having superior catalytic activity toward hydrogen evolution reaction (HER), is a prerequisite to realize large-scale hydrogen production. We present here a simple electrodeposition strategy of building nickel based alloy catalysts (NiM, M = Co, Cu, Mo, Au, Pt) on titanium (Ti) foils, which are subsequently utilized for catalyzing HER by seawater splitting. The preliminary results demonstrate that the Ti/NiCo and Ti/NiCo electrodes have superior catalytic activity for HER in seawater. All the Ti/NiM electrodes show relatively good long-term stability at −1.0 V vs. RHE over 10 h. The high efficiency and reasonable stability of the alloy catalysts demonstrate promising applications in the rising hydrogen revolution.