Electric Renewable Energy Sources Research Articles

Bryophyllum Pinnatum Leaf (BPL) is an Eternal Source of Renewable Electrical Energy for Future World

Modern civilization uses huge amount of electrical power. Most of this power is generated by using fossil fuel which is non-renewable and we can not produce it according to our desire .If this condition continue human civility will face great difficulties. In this case energy solution for the future will increasingly depend upon the uses of renewable energy. Keeping this concept in mind, an Innovative work has been designed and developed at the Physics Department of Jagannath University, Dhaka, Bangladesh. Electrochemistry and electrical Performances have been studied. The concentration of the reactant and product ions are [Cu2+] and [Zn2+]respectively measured by the Atomic Absorption Spectrophotometer (AAS). The variation of [Cu2+ ] and [Zn2+] with the variation of time, temperature of the electrolyte, concentration of the juice ,distance between two plates, absorption and adsorption of the [Cu2+ ] and [Zn2+] by the electrodes, thickness of the electrodes have been studied. Voltage regulation, Internal resistance, Energy efficiency, Current efficiency ,Voltage efficiency, Charging efficiency, Discharging efficiency , Open circuit Voltage, Short circuit Current of the BPL cell have been studied. It has been also studied the Voltage regulation, Internal resistance, Energy efficiency, Current efficiency ,Voltage efficiency, Charging efficiency, Discharging efficiency , Open circuit Voltage, Short circuit Current of the BPL cell with the variation of time. The name and presentation of the BPL cell has been developed . It has been introduced the name of the BPL cell as quasi Galvanic/Voltaic cell. Most of the results have been tabulated and graphically discussed.

Experimental Study on Direct Coupling in a Photovoltaic-Electrolyte Hydrogen Generation System

Hydrogen is the most potential clean energy in the twenty-first century and can be obtained by the electrolysis of water. As a secondary energy, its production would be restricted by large amount of energy consumption and low efficiency. It is advantageous if an electrolyser can be simply and efficiently coupled to a renewable source of electrical energy. In this paper, it investigated the optimal way to maximize the transference of energy from a photovoltaic (PV) array directly coupled to a polymer electrolyte membrane (PEM) electrolyser in a photovoltaic-electrolyte hydrogen generation system (PV hydrogen system). The pivotal strategy is to find the series parallel combination of the PV cells and electrolyser stacks, which produces the highest energy transfer efficiency. The optimal configuration is a PV array consisted of three parallel connected PV cells directly coupled to a PEM electrolyser consisted of twelve series-connected electrolyser stacks with a day energy transfer efficiency of 99.52%. Comparisons between direct coupling systems and traditional ones have been presented. The result shows that direct coupling technology is feasible to improve the energy transfer efficiency in a PV hydrogen system.

Do renewable electricity policies promote renewable electricity generation? Evidence from panel data

Using the Poisson pseudo-maximum likelihood estimation technique, this paper evaluates the effects of renewable electricity policies on renewable electricity generation using a large panel dataset that covers 122 countries over the period of 1980–2010. The results suggest that renewable electricity policies play a crucial role in promoting renewable electricity generation, but their effectiveness is subject to diminishing returns as the number of policies increases. There is also evidence that the effects of renewable electricity policies are more pronounced before 1996 as well as in developed and emerging market countries, and the negative policy interaction effect fades with the stage of economic development. Lastly, policy effectiveness varies by the type of renewable electricity policy and energy source. Only investment incentives and feed-in tariffs are found to be effective in promoting the development of all types of renewable energy sources for electricity considered in this paper.

Reaction intermediates of ethanol electro-oxidation on platinum investigated by SFG spectroscopy

Although electrochemical oxidation of simple organic molecules on metal catalysts is the basic ingredient of fuel cells, which have great technological potential as a renewable source of electrical energy, the detailed reaction mechanisms are in most cases not completely understood. Here, we investigate the ethanol–platinum interface in acidic aqueous solution using infrared–visible sum frequency generation (SFG) spectroscopy and theoretical calculations of vibrational spectra in order to identify the intermediates present during the electro-oxidation of ethanol. The complex vibrational spectrum in the fingerprint region imply on the coexistence of several adsorbates. Based on spectra in ultra-high-vacuum (UHV) and electrochemical environment from the literature and our density functional theory (DFT) calculations of vibrational spectra, new adsorbed intermediates, never before observed with conventional infrared (IR) spectroscopy, are proposed here: η2-acetaldehyde, η2-acetyl, ethylidyne, monodentate acetate, methoxy, tertiary methanol derivative, COH residue, η2-formaldehyde, mono and bidentate formate, CH3 and CH2 residues. In addition, we present new evidences for an ethoxy intermediate, a secondary ethanol derivative and an acetyl species, and we confirm the presence of previously observed adsorbates: a tertiary ethanol derivative, bidentate acetate, and COad. These results indicate that the platinum surface is much more reactive, and the reaction mechanism for ethanol electro-oxidation is considerably more complex than previously considered. This might be also true for many other molecule-catalyst systems.

Households’ Perceptions on Electricity Consumption in Slovenia

The electricity market liberalisation for households in Slovenia aims to encourage new suppliers’ entries and thus greater market competition in electricity supply. It is interesting to investigate how households’ consumption in Slovenia has reacted in response to new opportunities in selection of suppliers and what are the Slovenian households’ consumers perceptions in electricity consumption and in using more energy savings approaches in consumption of electrical energy. In 2010, we have conducted surveys with the sample of the Slovenian households’ electricity consumers. The questions relate to the households perceptions on estimation of competition in households’ electricity markets and on perceptions to implement in a household practice more efficient electrically energy savings strategies. The collected survey data are processed by use of summary statistics and multivariate factor analysis. We have found the increasing awareness and perceptions of the Slovenian households towards better quality of electricity supply with advices in savings strategies of electricity consumption, but still a bit less towards more electrical energy consumption from the renewable sources of electrical energy. This implies that additional promotional and educational activities are needed to comply with the objectives to encourage a greater market competition as well as to improve households’ efficiency in energy use and to increase the use of electrical energy from the renewable sources of energy.

Economic and environmental aspects of the component sizing for a stand-alone building energy system: A case study

When designing a building energy system based on renewable energy sources, a major challenge is the suitable sizing of its components. In this paper, a simulation tool is presented for determining the optimal sizes of the main components of a stand-alone building energy system which integrates both thermal and electric renewable energy sources. Since the control of this multisource energy system is a non-trivial, multivariable control problem, particular emphasis is placed on the energy management system. A control structure based on model predictive control is proposed, whereas the underlying optimal control problem is formulated as a mixed-integer linear programming problem.The simulation tool developed is successfully applied on the specific case of an alpine lodge. A set of potential configurations, each being optimal with respect to both the net present costs and the global warming potential, is generated by analyzing the system for various component sizes. Out of this set, the decision makers can choose the most cost efficient configuration fulfilling their specifications.

Impact of wind power on sizing and allocation of reserve requirements

The increasing share of renewable energy sources for electricity, driven by variable output technologies such as wind and solar photovoltaics, is expected to have an impact on the operational reserve requirements of power systems. This study applies a probabilistic approach to estimate reserve requirements and establishes a methodology that makes it possible to distinguish between different categories of reserves based on the imbalance drivers of wind power. The methodology is based on sizing fast-response reserves based on the distribution of output fluctuations inside the settlement period, and sizing slow-response reserves based on the distribution of the average prediction error over the settlement period. The main advantage of this methodology is a reduction of the fast-response reserves, which are generally assessed as expensive compared to slow-response reserves. This approach is applied in a case study and compared with alternative strategies. The results for 500 MW of wind power installed in a North Sea country confirm these reductions and show that with the suggested approach the required fast-response and slow-response reserves, respectively, amount to 7 and 23-26% of the installed wind power capacity.

Nationally Exclusive Support Schemes for RES Electricity Production and the Free Movement of Goods

Directive 2009/28/EC requires Member States to adopt support schemes for the promotion of electricity from renewable energy sources (RES) while explicitly allowing them to exclude RES electricity produced in a different Member State from their scope of application. In its notorious PreussenElektra-judgment, the ECJ held that this geographical limitation could be justified on environmental protection grounds. The pending Essent Belgium case now provides an opportunity to reconsider the conformity of nationally exclusive support schemes with the rules governing the free movement of goods. In his opinion, Advocate General Bot deems nationally exclusive support schemes to be no longer compatible with the internal market for electricity. This paper, in contrast, argues that nationally exclusive support schemes remain necessary in order to guarantee their effectiveness and cost-efficiency in the absence of a harmonised approach to RES support policies at EU level. Furthermore, it regards their national design as being in line with the principles of EU environmental and energy policy.

Effect of demand response on the marginal electricity used by plug-in electric vehicles

Plug-in electric vehicles (PEV) are considered to be a potentially sustainable alternative to conventional vehicles for private transport and a way of balancing intermittent generation from renewable energy sources (RES). Using RES for electric mobility would be superior to all available fossil generation alternatives in terms of emissions and efficient energy conversion. To quantify the marginal energy from RES used, two charging strategies last trip charging and optimized demand-side management (DSM) with dynamic pricing are investigated for a German long-term high RES power mix scenario. The results for both charging cases indicate that the power demand for PEVs will not be met by RES. For last trip charging 1.40% comes from RES. In terms of DSM this share increases to 7.38% but results in higher overall CO2 emissions because for Germany coal provides the lowest cost fossil power. Hence DSM charging reduces peak load and helps to balance RES generation but is contrary to the original idea of clean transportation because of higher marginal emissions caused by the utilisation of coal. To account for contractual arrangements allowing consumers to directly purchase RES electricity, a second scenario with additional installed RES capacity is analysed. Because of the high RES share of over 50 % a complete usage of the RES is not possible and a small fraction of power must still be provided by dispatchable power plants. For the second scenario, DSM charging also allows for an increased use of RES compared to last trip charging (99 % versus 90% RES). In addition, total marginal CO2 emissions are lower and DSM helps to balance the ramping of RES. Therefore, it is concluded that for Germany the installation of additional RES and DSM charging would guarantee clean transportation using electric vehicles.

Assessing Climate Change Impacts on Global Hydropower

Currently, hydropower accounts for close to 16% of the world’s total power supply and is the world’s most dominant (86%) source of renewable electrical energy. The key resource for hydropower generation is runoff, which is dependent on precipitation. The future global climate is uncertain and thus poses some risk for the hydropower generation sector. The crucial question and challenge then is what will be the impact of climate change on global hydropower generation and what are the resulting regional variations in hydropower generation potential? This paper is a study that aims to evaluate the changes in global hydropower generation resulting from predicted changes in climate. The study uses an ensemble of simulations of regional patterns of changes in runoff, computed from global circulation models (GCM) simulations with 12 different models. Based on these runoff changes, hydropower generation is estimated by relating the runoff changes to hydropower generation potential through geographical information system (GIS), based on 2005 hydropower generation. Hydropower data obtained from EIA (energy generation), national sites, FAO (water resources) and UNEP were used in the analysis. The countries/states were used as computational units to reduce the complexities of the analysis. The results indicate that there are large variations of changes (increases/decreases) in hydropower generation across regions and even within regions. Globally, hydropower generation is predicted to change very little by the year 2050 for the hydropower system in operation today. This change amounts to an increase of less than 1% of the current (2005) generation level although it is necessary to carry out basin level detailed assessment for local impacts which may differ from the country based values. There are many regions where runoff and hydropower generation will increase due to increasing precipitation, but also many regions where there will be a decrease. Based on this evaluation, it has been concluded that even if individual countries and regions may experience significant impacts, climate change will not lead to significant changes in the global hydropower generation, at least for the existing hydropower system.

Alternative energy technologies as a cultural endeavor: a case study of hydrogen and fuel cell development in Germany

The wider background to this article is the shift in the energy paradigm from fossil energy sources to renewable sources which should occur in the twenty-first century. This transformation requires the development of alternative energy technologies that enable the deployment of renewable energy sources in transportation, heating, and electricity. Among others, hydrogen and fuel cell technologies have the potential to fulfill this requirement and to contribute to a sustainable and emission-free transport and energy system. However, whether they will ever reach broad societal acceptance will not only depend on technical issues alone. The aim of our study is to reveal the importance of nontechnical issues. Therefore, the article at hand presents a case study of hydrogen and fuel cells in Germany and aims at highlighting the cultural context that affects their development. Our results were obtained from a rich pool of data generated in various research projects through more than 30 in-depth interviews, direct observations, and document analyses. We found that individual and collective actors developed five specific supportive practices which they deploy in five diverse arenas of meaning in order to attach certain values to hydrogen and fuel cell technologies. Based on the results, we drew more general conclusions and deducted an overall model for the analysis of culture in technological innovations that is outlined at the end of the article. It constitutes our contribution to the interdisciplinary collaboration required for tackling the shift in this energy paradigm.

Experimental Smart Grid

The paper deals with activities towards a design of a methodology to stabilize already existing electrical grids and at the same time utilize the maximum of electrical energy from renewable electrical energy sources. The authors believe that the first step towards a methodology is to create a thorough model of the electrical grid with connecting most suitable existing renewable as well as classic electric energy sources. There is also described an idea of an experimental smart grid, but the main attention is given to the physical realization of a laboratory model of the smart grid. The authors described an electronic design and an idea of control strategy to enhance a functionality, stability and effectiveness of the grids with a significant share of the renewable energy sources.

Experimental investigation of solar-hydrogen energy system performance

Recently, the Solar-hydrogen energy system (SHES) becomes a reality thanks as well as a very common topic to energy research in Egypt as it is now being the key solution of different energy problems including global warming, poor air quality and dwindling reserves of liquid hydrocarbon fuels. Hydrogen is a flexible storage medium for energy and can be generated by the electrolysis of water. It is more particularly advantageous and efficient when the electrolyzer is simply coupled to a source of renewable electrical energy. This paper examines the operation of alkaline water electrolysis coupled with solar photovoltaic (PV) source for hydrogen generation with emphasis on the electrolyzer efficiency. PV generator is simulated using Matlab/Simulink to obtain its characteristics under different operating conditions with solar irradiance and temperature variations. The experimental alkaline water electrolysis system is built in the fluid mechanics laboratory of Menoufiya University and tested at certain input voltages and currents which are fed from the PV generator. The effects of voltage, solution concentration of electrolyte and the space between the pair of electrodes on the amount of hydrogen produced by water electrolysis as well as the electrolyzer efficiency are experimentally investigated. The water electrolysis of different potassium hydroxide aqueous solutions is conducted under atmospheric pressure using stainless steel electrodes. The experimental results showed that the performance of water electrolysis unit is highly affected by the voltage input and the gap between the electrodes. Higher rates of produced hydrogen can be obtained at smaller space between the electrodes and also at higher voltage input. The maximum electrolyzer efficiency is obtained at the smallest gap between electrodes, however, for a specified input voltage value within the range considered.

Law & Economics Perspectives on Electricity Regulation

This paper first reviews some of the main contributions of the new institutional economics to the analysis of the process of competitive transformation of network industries. It shows that neo-institutional analysis is complementary to the microeconomics of rational pricing, since it accounts for the decisive role of an institutional framework adapted to new transactions. It emphasizes the importance of the political reform process, which draws on the conditions of attractiveness and feasibility to define an initial reorganization of property rights in these industries. The paper then analyzes in this light some of the main challenges ahead for electricity regulation: the question of investment in generation capacities and the link to long term contracts, the regulation of wholesale market power, the support to Renewable Energy Sources for Electricity (RES-E) and the design of new regulatory authorities.

Modelling the dynamic response of a solid oxide steam electrolyser to transient inputs during renewable hydrogen production

Hydrogen is regarded as a leading candidate for alternative future fuels. Solid oxide electrolyser cells (SOEC) may provide a cost-effective and green route to hydrogen production especially when coupled to a source of renewable electrical energy. Developing an understanding of the response of the SOEC stack to transient events that may occur during its operation with intermittent electricity input is essential before the realisation of this technology. In this paper, a one-dimensional (1D) dynamic model of a planar SOEC stack has been employed to study the dynamic behaviour of such an SOEC and the prospect for stack temperature control through variation of the air flow rate. Step changes in the average current density from 1.0 to 0.75, 0.5 and 0.2 A/cm2 have been imposed on the stacks, replicating the situation in which changes in the supply of input electrical energy are experienced, or the sudden switch-off of the stack. Such simulations have been performed both for open-loop and closed-loop cases. The stack temperature and cell voltage are decreased by step changes in the average current density. Without temperature control via variation of the air flow rate, a sudden fall of the temperature and the cell potential occurs during all the step changes in average current density. The temperature excursions between the initial and final steady states are observed to be reduced by the manipulation of the air flow rate. Provided that the change in the average current density does not result in a transition from exothermic to endothermic operation of the SOEC, the use of the air flow rate to maintain a constant steady-state temperature is found to be successful.

On the physics of power, energy and economics of renewable electric energy sources – Part I

Environmental concerns have increasingly led to the installation of Renewable Energy Technologies (RETs) despite the fact that they are recognized as expensive. Innovative efforts within the area are beset with difficulties [1], and they are at risk of producing misdirected or insignificant improvements in terms of the cost effectiveness of total energy conversion systems. This paper investigates how RETs can be evaluated, in terms of economy and engineering solutions, by studying the fundamental physics of renewable energy sources and how it matches with the RETs. This match is described by the “Degree of Utilization”. The findings indicate that new innovations should focus on the possible number of full loading hours. RETs that are correctly matched to their energy source generate a higher amount of electric energy and have a higher potential of becoming more competitive. In cases where this aspect has been ignored, leading to relatively small degrees of utilization, it can be understood as an engineering mismatch between installed power, converted energy, and the fundamental physics of the renewable energy sources. Since there is a strong and possibly biased support for so-called mature RETs and already existing solutions, a clarification of how fundamental physical laws affect the cost of investments and payback of investments is needed. The present paper is part I out of II and it focuses on the difference between power and energy and the physics of different energy sources and their utilization.

On the physics of power, energy and economics of renewable electric energy sources - Part II

Renewable Energy Technologies (RETs) are often recognized as less competitive than traditional electric energy conversion systems. Obstacles with renewable electric energy conversion systems are often referred to the intermittency of the energy sources [1] and the relatively high maintenance cost. However, due to an intensified discourse on climate change and its effects, it has from a societal point of view, become more desirable to adopt and install CO 2 neutral power plants. Even if this has increased the competitiveness of RETs in a political sense, the new goals for RET installations must also be met with economical viability. We propose that the direction of technical development, as well as the chosen technology in new installations, should not primarily be determined by policies, but by the basic physical properties of the energy source and the associated potential for inexpensive energy production. This potential is the basic entity that drives the payback of the investment of a specific RET power plant. With regard to this, we argue that the total electric energy conversion system must be considered if effective power production is to be achieved, with focus on the possible number of full loading hours and the Degree of Utilization [2]. This will increase the cost efficiency and economical competitiveness of RET investments, and could enhance faster diffusion of new innovations and installations without over-optimistic subsidies. This paper elaborates on the overall problem of the economy of renewable electric energy conversion systems by studying the interface between physics, engineering and economy reported for RET power plants in different scientific publications. The core objective is to show the practical use of the Degree of Utilization and how the concept is crucial for the design and economical optimization disregarding subsidies. The results clearly indicate that the future political regulative frameworks should consider the choice of renewable energy source since this strongly affects the economical output from the RET power plants.

Direct coupling of an electrolyser to a solar PV system for generating hydrogen

Hydrogen as an energy currency, carrier and storage medium may be a key component of the solution to problems of global warming, poor air quality and dwindling reserves of liquid hydrocarbon fuels. Hydrogen is a flexible storage medium and can be generated by the electrolysis of water. It is particularly advantageous if an electrolyser may be simply and efficiently coupled to a source of renewable electrical energy. This paper examines direct coupling of a polymer electrolyte membrane (PEM) electrolyser to a matched solar photovoltaic (PV) source for hydrogen generation and storage. Such direct coupling with minimum interfacing electronics would lead to substantial cost reduction and thereby enhance the economic viability of solar-hydrogen systems. The electrolyser is designed for fail-safe operation with multiple levels of safety and operational redundancy. A control system in the electrolyser unit provides for disconnection when required and for auto-start in the morning and auto shut-down at night, simultaneously addressing the goals of minimum energy loss and maximum safety. The PV system is a 2.4 kW array (20.4 m 2 total area) comprising 30, 12 V, 80 W, Solarex polycrystalline modules in a series–parallel configuration. The integrated system has been operated for approximately 60 days over a 4-month period from September 2007 to January 2008 with many periods of unattended operation for multiple days, experiencing weather ranging from hot and sunny (above 40 °C) to cool and cloudy. The principle and practicality of direct coupling of a suitably matched PV array and PEM electrolyser have been successfully demonstrated. Details of electrolyser operation coupled to a PV array along with modelling work to match current–voltage characteristics of the electrolyser and PV system are described.

Running the world on renewables: Hydrogen transmission pipelines and firming geologic storage

On every continent, diverse renewable resources could supply all humanity's future energy needs. Earth's richest renewable energy resources—large in geographic extent, high intensity—are usually stranded: far from end-users without gathering and transmission systems. The output of most renewables varies greatly, at time scales of seconds to seasons: the energy capture assets thus operate at inherently low capacity factor (CF), and energy delivery is not ‘firm’. New electric transmission systems dedicated to renewables will suffer the same low CF and represent substantial stranded capital assets. At gigawatt (GW) scale, renewable-source electricity could be converted to hydrogen and oxygen, via high-pressure-output electrolyzers. Hydrogen would be pipelined to load centers for use as vehicle fuel, retail-value combined-heat-and-power generation on the customers' side of meters, ammonia production, and refinery feedstock. Great Plains, U.S.A. wind energy alone, if fully harvested and pipelined to markets, could supply all U.S.A. energy. About 15000 new, large, solution-mined Great Plains salt caverns could economically store enough energy as compressed hydrogen to ‘firm’ this wind power at annual scale, at an incremental capital cost to the generation–transmission system of 5–10%. Worldwide, firming in geologic formations adds great market and strategic value to diverse, stranded, and abundant renewables. Copyright © 2008 John Wiley & Sons, Ltd.

On the performance of commercial supercapacitors as storage devices for renewable electrical energy sources

On the performance of commercial supercapacitors as storage devices for renewable electrical energy sources