Hasil untuk "Renewable energy sources"

Nathalie Ronayette, Sonia Sousa Nobre, Sandrine Barthélémy et al.

New solar cells’ technologies such as silicon heterojunction and tandem solar cells raise new challenges such as temperature-induced degradations, which are problematic for the cells’ interconnection. Electrically Conductive Adhesives (ECAs), usually made of silver particles embedded in a polymeric matrix, seem a promising technology to allow low-temperature interconnection, but raise concern about a high consumption of silver in the manufacture of photovoltaic (PV) panels. In this work, the fabrication of copper-based ECAs is presented as an approach to reduce the silver consumption of the interconnection process. Core-shell copper-silver particles with dendritic shapes that showed resistant to oxidation up to 220°C were used as conductive fillers. Their integration into an acrylate fast-curing matrix was performed in ratios of 59 wt% and 69 wt% fillers, respectively accounting for silver contents of 3.0 wt% and 3.5 wt%. The resulting pastes have resistivities of 3.5 * 10‑3 Ω*cm and 9.0 * 10-4 Ω*cm respectively, globally similar to those of commercial ECAs dedicated to the interconnection of solar cells. Their fast-curing process was measured to occur upon heating at 105°C, and be completed upon heating at 160°C during 20 seconds, enabling high throughputs. First trials of these ECAs into strings of solar cells were made: the stencil-printed patterns had a good quality, but a poor adhesion between the solidified ECAs and the ribbons prevents their further use.

Osita U. Omeje, Olanrewaju M. Bankole, Daniel E. Okojie et al.

Abstract Accurate fault location in transmission lines remains a critical challenge for modern power systems, particularly as networks become increasingly complex with the integration of renewable energy sources and smart grid technologies. Traditional fault location methods often need help with high-impedance faults, non-homogeneous line parameters, and dynamic system conditions, leading to extended outage durations and reduced system reliability. This study addresses these challenges by developing an enhanced fault location method that combines conventional electromagnetic principles with advanced machine learning techniques. The methodology employs an approach that integrates modified impedance-based calculations with convolutional neural networks and machine learning regression. The method was validated using a modified IEEE 39-bus test system through simulations, incorporating several fault scenarios and system conditions. Testing utilised synchronised measurements from both transmission line ends, with data captured at 4096 samples per second. Results demonstrate significant improvements over existing techniques, achieving a 99.1% fault detection rate, 98.2% classification accuracy, and 1.2% mean absolute percentage error in location estimation. The method showed particular strength in challenging scenarios, reducing errors by 79.4% for high-impedance faults and maintaining accuracy under variable renewable generation conditions. The proposed method advances power system protection by providing a robust, adaptive solution suitable for modern grid requirements. Its conventional instrumentation implementation facilitates practical adoption, offering improved reliability and reduced outage durations in real-world applications.

Cheng Zhang, Wei Fang, Changjun Xie et al.

Integrated Hydrogen–Energy Systems (IHES) have attracted widespread attention; however, distributed energy sources such as photovoltaics (PV) and wind turbines (WT) within these systems exhibit significant uncertainty and intermittency, posing key challenges to scheduling complexity and system instability. As a core mechanism for the integrated operation of IHES, electricity price regulation can promote the absorption of renewable energy, optimize resource allocation, and enhance operational economy. Nevertheless, uncertainties in IHES hinder the formulation of accurate electricity prices, which easily lead to delays in scheduling responses and an increase in cumulative operating costs. To address these issues, this study develops lifespan models for Proton Exchange Membrane Electrolyzers (PEMELs) and Proton Exchange Membrane Fuel Cells (PEMFCs), constructs dynamic equations for the demand side and response side, and proposes a fuzzy-weighted dynamic pricing strategy. Simulation results show that, compared with fixed pricing, the proposed dynamic pricing strategy reduces economic indicators by an average of 15.3%, effectively alleviates energy imbalance, and optimizes the energy supply of components. Additionally, it reduces the lifespan degradation of PEMELs by 21.59% and increases the utilization rate of PEMFCs by 54.8%.

Mitra Nabian Dehaghani, Tarmo Korotko, Argo Rosin

The integration of distributed generation (DG), renewable energy sources (RES), and power electronic converters into distribution systems (DSs) has introduced significant power quality (PQ) challenges, such as voltage fluctuations, harmonic distortions, and transients. These issues can undermine the reliability and stability of power systems, making it essential to address them to ensure a consistent and resilient power supply, especially as RES adoption continues to grow. While previous reviews have explored artificial intelligence (AI) applications for PQ management, most have been limited to specific AI techniques or targeted PQ problems, such as harmonics. This review, however, offers a comprehensive synthesis of AI-based approaches across a wide range of PQ applications, encompassing detection, classification, and improvement, while also considering the specific PQ issues addressed in each case. By adopting an integrated approach, this review identifies key research gaps, particularly the limited focus on leveraging AI to control power converters in RESs for PQ improvement, as most existing studies emphasize devices like active power filters, compensators, and conditioners. The review also evaluates the effectiveness of these AI methods in terms of accuracy and the extent of total harmonic distortion (THD) reduction. In addition, it provides novel insights that can help guide researchers, engineers, and industry professionals toward developing more adaptive, scalable, and robust PQ solutions. Finally, future research directions are proposed to advance AI-based PQ management, facilitating the integration of AI into diverse and evolving power systems.

Elham Nejadmoghadam, Abdenour Achour, Olov Öhrman et al.

Understanding and mitigating catalyst deactivation is crucial for enhancing the efficiency of hydrodeoxygenation (HDO) processes in the production of biofuels. In this study sulfided metal catalysts, NiMo/Al2O3, NiMo/SiO2-Al2O3, and NiW/Al2O3 along with bare supports (Al2O3, SiO2-Al2O3, and zeolite Y) were placed in a refinery green hydrotreating unit. Potassium, phosphorus and sodium were identified as major poisons. The HDO activity of spent catalysts was assessed in a lab-scale batch reactor at 58 bar H2 and 325 °C for deoxygenation of oleic acid. The results highlighted that the active metals, particularly NiW, had a more pronounced tendency to attract poisons compared to the supports. However, with bare supports, coking was more significant and simultaneously less poisons were trapped, which could be due to blocking of the pores with coke. In the presence of these poisons there was a significant decline in oxygenate conversion compared with fresh catalysts, with a gradual reduction in activity for both decarbonation and direct-HDO products. Solvent washing treatments with DMSO and water were employed in an attempt to recover the activity of the spent catalysts, by partially removing the poisons. However, through these treatments, the activity of the NiMo/Al2O3 catalyst could not be restored.

Xuefeng Li, Shibo Wang, Yu Chen

This article investigates the fragmentation of rock during the indentation process with a conical pick. The study explores the impact of indentation dip angle, indentation spacing, and confining pressure on rock fragmentation through simulation using the discrete element method. Rock models of coal and red sandstone are created and calibrated for the simulation. The findings indicate that the indentation force increases exponentially with the increase of indentation dip angle for both coal and red sandstone. The specific energy increases first and then decreases with the increase of indentation dip angle. The maximum specific energy is found in the condition of indentation dip angle of 25° for red sandstone, while it is 20° for coal. The indentation force increases logarithmically with the increase of indentation spacing tending to be an unrelieved indentation condition. The optimal indentation spacing with the lowest specific energy is determined to be 50 mm for breaking coal and 34 mm for breaking red sandstone. Additionally, the indentation force increases exponentially for coal while it increases linearly for red sandstone with the increase of the confining pressure. For both coal and red sandstone, specific energy increases with the increase of the confining pressure.

S. Tamaro, F. Campagnolo, C. L. Bottasso

<p>We present an active power control (APC) algorithm for wind farms that operates wind turbines to maximize their power availability in order to robustly track a reference power signal in the presence of turbulent wind lulls. The operational setpoints of the wind turbines are optimized using an engineering flow model by combining induction control with wake steering. The latter has the goal of deflecting low-momentum wakes and increasing power margins. The algorithm also features a proportional–integral closed loop inspired by the literature to correct potential errors deriving from the offline computation of the setpoints.</p> <p>First, we demonstrate the new approach in steady-state conditions, showing how the availability of power is increased by mitigating wake interactions. We observe that our proposed method is particularly effective in conditions of strong wake impingement, occurring in scenarios of high power demand. Next, considering two wind farm layouts, we compare the performance of the algorithm to three state-of-the-art reference APC formulations in unsteady scenarios using large-eddy simulations coupled with the actuator line method (LES-ALM). We show that the occurrence and treatment of local temporary instances of power unavailability (<i>saturations</i>) dramatically affect power tracking accuracy. The proposed method yields superior power tracking due to the increased power margins that limit the occurrence of saturation events. Additionally, we show that this performance is achieved with reduced structural fatigue.</p>

J. P. Murcia Leon, H. Habbou, M. Friis-Møller et al.

<p>Hybrid renewable power plants consisting of collocated wind, solar photovoltaic (PV), and lithium-ion battery storage connected behind a single grid connection can provide additional value to the owners and society in comparison to individual technology plants, such as those that are only wind or only PV. The hybrid power plants considered in this article are connected to the grid and share electrical infrastructure costs across different generation and storing technologies. In this article, we propose a methodology for sizing hybrid power plants as a nested-optimization problem: with an outer sizing optimization and an internal operation optimization. The outer sizing optimization maximizes the net present values over capital expenditures and compares it with standard designs that minimize the levelized cost of energy. The sizing problem formulation includes turbine selection (in terms of rated power, specific power, and hub height), a wind plant wake loss surrogate, simplified wind and PV degradation models, battery degradation, and operation optimization of an internal energy management system. The problem of outer sizing optimization is solved using a new parallel “efficient global optimization” algorithm. This new algorithm is a surrogate-based optimization method that ensures a minimal number of model evaluations but ensures a global scope in the optimization. The methodology presented in this article is available in an open-source tool called HyDesign. The hybrid sizing algorithm is applied for a peak power plant use case at different locations in India where renewable energy auctions impose a monetary penalty when energy is not supplied at peak hours. We compare the hybrid power plant sizing results when using two different objective functions: the levelized cost of energy (<span class="inline-formula">LCoE</span>) or the relative net present value with respect to the total capital expenditure costs (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f147e6b10aef704514edc5586dee8b93"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00001.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00001.png"/></svg:svg></span></span>). Battery storage is installed only on <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="0c97fe39a91af71c5f466cc2e94b80af"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00002.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00002.png"/></svg:svg></span></span>-based designs, while the hybrid design, including wind, solar, and battery, only occurs on the site with good wind resources. Wind turbine selection on this site prioritizes cheaper turbines with a lower hub height and lower rated power. The number of batteries replaced changes at the different sites, ranging between two or three units over the lifetime. A significant oversizing of the generation in comparison to the grid connection occurs on all <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mrow class="chem"><mi mathvariant="normal">NPV</mi></mrow><mo>/</mo><mrow class="chem"><msub><mi mathvariant="normal">C</mi><mi mathvariant="normal">H</mi></msub></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="a79fa39f5ba41b881215ca0cbb33976d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="wes-9-759-2024-ie00003.svg" width="44pt" height="14pt" src="wes-9-759-2024-ie00003.png"/></svg:svg></span></span>-based designs. As expected <span class="inline-formula">LCoE</span>-based designs are a single technology with no batteries.</p>

Ying Li, Zeng-Xue Li, Dong-Dong Wang et al.

Taking the upper sub-member of Sha 4 in Well Fanye 1 and Well Niuye 1 in Dongying Sag, Jiyang Depression, Bohai Bay Basin as a typical example, this paper adopts the method of combining macro and micro laminar characterization and complementing each other. The characteristics of laminar development are studied by means of fine description of rock thin sections by cores and electron microscopic observation Reconstruction of the Bohai Bay Basin in sand four period of ancient sedimentary environment, it is concluded that the sand on the four period of development of four complete filling sedimentary cycle. Using Milankovitch cycles method, reveals the ancient climate control mechanism of lithofacies, formed by organic laminae under hot and humid climate and a small amount of calcite laminated lithofacies, in hot and humid climate, the lithofacies is mainly composed of organic lamina and a small amount of calcite lamina, while in cold and dry climate, the lithofacies is mainly composed of calcite lamina, and the lithofacies is mainly composed of organic lamina, silty lamina and gypsum lamina. Micro-laminar research is an important scientific issue in unconventional oil and gas eology. It can provide basic data for unconventional oil and gas exploration, such as the types, distribution and extension of laminar, especially the determination of sampling targets. Different laboratory samples can be analyzed according to the laminar types.

Siming Zhao, Baoshun Wang, Na Zhu et al.

Abstract Smart windows refer to those which can dynamically modulate the transmitted light by changing their colors. Dual‐band electrochromic materials (ECMs) refer to materials that can change their colors and regulate light transmission in both visible (VIS) and infrared (IR) regions under different voltages. The dual‐band ECMs‐based building windows can thus regulate the indoor temperature to reduce the energy consumption for heating and air‐conditioning systems. Therefore, the wide application of ECMs in building windows will contribute a lot to establishing an energy‐saving society. During the past decades, enormous efforts have been made to improve the performance of dual‐band ECMs. This review presents a summary of the recent progress of dual‐band ECMs, focusing on their modulation mechanism, material design, and performance optimization. Finally, the challenges and outlook of dual‐band ECMs are also discussed.

Xiaoqiang Du, Yangyang Ding, Xiaoshuang Zhang

Water electrolysis is a promising technology to produce hydrogen but it was severely restricted by the slow oxygen evolution reaction (OER). Herein, we firstly reported an advanced electrocatalyst of MOF-derived hollow Zn–Co–Ni sulfides (ZnS@Co9S8@Ni3S2-1/2, abbreviated as ZCNS-1/2) nanosword arrays (NSAs) with remarkable hydrogen evolution reaction (HER), OER and corresponding water electrolysis performance. To reach a current density of 10 mA cm−2, the cell voltage of assembled ZCNS-1/2//ZCNS-1/2 for urea electrolysis (1.314 V) is 208 mV lower than that for water electrolysis (1.522 V) and stably catalyzed for over 15 h, substantially outperforming the most reported water and urea electrolysis electrocatalysts. Density functional theory calculations and experimental result clearly reveal that the properties of large electrochemical active surface area (ECSA) caused by hollow NSAs and fast charge transfer resulted from the Co9S8@Ni3S2 heterostructure endow the ZCNS-1/2 electrode with an enhanced electrocatalytic performance.

Yongli Zhu, Chanan Singh

This letter develops a fast analytical method for uncertainty quantification of electromechanical oscillation frequency due to varying generator dampings. By employing the techniques of matrix determinant reduction, two types of uncertainty analysis are investigated to quantify the impact of the generator damping on electromechanical oscillation frequency, i.e., interval analysis and probabilistic analysis. The proposed analytical frequency estimation formula is verified against conventional methods on two transmission system models. Then, Monte Carlo experiments and interval analysis are respectively conducted to verify the established lower/upper bound formulae and probability distribution formulae. Results demonstrate the accuracy and speed of the proposed method.

Pedro Luis Camuñas García-Miguel, Jaime Alonso-Martinez, Santiago Arnaltes Gómez et al.

Participation in the electricity market requires making commitments without knowing the real generation or electricity prices. This is problematic for renewable generators due to their fluctuating output. Battery energy storage systems (BESSs) integrated with renewable sources in a hybrid farm (HF) can alleviate imbalances and increase power system flexibility. However, the impact of battery degradation on long-term profitability must be taken into account when choosing the correct market participation strategy. This study evaluates the state-of-the-art on energy management systems (EMS) for HFs participating in day-ahead and intraday markets, incorporating both BESSs’ calendar and cycling degradation. Results suggest that efforts to attain additional profits in intraday markets can be detrimental, especially when the degradation effect is considered in the analysis. A new market participation strategy is proposed that aims to address the limitations of market overlapping and forecasting errors. The results demonstrate that the proposed method can enhance long-term benefits while also reducing battery degradation.

Jarosław Solarz, Małgorzata Gawlik-Kobylińska, Witold Ostant et al.

Energy security education explores various issues, such as a secure and competitive economy and nuclear safety. In the context of energy transition and sustainable development, it also addresses the world’s reliance on nonrenewable and renewable energy sources. The aim of this study was to identify research trends pertaining to energy security education, paying particular attention to renewable and nonrenewable sources. This was accomplished with the use of mixed-method research in two steps. The first step was a text-mining and content analysis of publications on energy security education published on the Web of Science platform between 2016 and 2021. From 660 publications on energy security education, titles, abstracts, and keywords were extracted and analysed with NVivo software to identify the most frequent concepts on energy sources in publications. The concepts were associated with nonrenewable energy sources (coal, natural gas, uranium, petroleum, and fossil fuels), nuclear power, and renewable energy sources (hydro, geothermal, solar, tide/wave/ocean, wind, solid biofuels, biogases, liquid biofuels, and renewable municipal waste). The second step was conducting detailed searches with Boolean operators, where “energy security education” was juxtaposed with the distinguished keywords. All searches on energy security education showed that publication activity tended to decrease, while citations increased. The most explored topics concerned: “fossil fuels”, “oil, petroleum”, “renewable” energy, and “solar” energy sources. An increasing trend was observed for all renewable energy sources as well as selected nonrenewable sources: “oil, petroleum”, “nonrenewable”, and “coal”. Additionally, R-squared values were calculated to indicate the fit of the trendline to the model. Due to the technologically enhanced energy transition and didactic innovations, education focussing on energy sources is expected to remain in demand. Curricula will need to be revised in the future to better reflect this reality.

Ernest C. Nwosu, Godswill N. Nwaji, Chibuike Ononogbo et al.

The demand for freshwater has continued to soar amidst an increasing population, industrialization, and environmental pollution. The continuous shrinkage of this important resource has necessitated the need for a concerted effort on seawater desalination. Solar-powered desalination occupies a strategic position in the water-energy nexus and offers an alternative to taking off pressure from the already stressed freshwater sources. A numerical study with experimental validation of a single-slope double-effect solar still integrated with paraffin wax is thus presented. A transient mathematical model considering the humid air media in the upper and lower chambers was developed. Previous works in this area ignored the thermal analysis of the humid air medium, and as such, adopted the evaporation theory in the estimation of the freshwater yield. However, this study considers the thermal resistance offered by the humid air in the computation of the yield using the condensation theory. The energy-balance equations were discretized using the finite element method and solved with the aid of version 7.12 of the FlexPDE numerical solver. The model was validated with data from the experimental study. The correlation coefficients between the predicted and experimental data showed good agreement with values in the range of 0.97≤r≤0.99, and values of root mean square percent deviation of 3.2%≤e≤16.8%. The system achieved its best performance in November with a daily yield of 4.06 kg/m2 and a mean efficiency of 33.7%. The upper basin contributed an average of 52% of the total yield with a greater percentage of its yield occurring during the nocturnal phase. The effects of the upper basin and the PCM on the diurnal performance of the system were evaluated.

Grzegorz Augustyn, Jerzy Mikulik, Rafał Rumin et al.

Contemporary agriculture has become very energy-intensive and mainly uses electricity, which is needed for technological processes on livestock farms. Livestock faeces are burdensome for the environment due to the release of methane into the atmosphere. This article presents the concept of a self-sufficient livestock farm as an off-grid energy circuit that is a part of the agricultural process. The key idea is to obtain an energy flow using the concept of a smart valve to achieve a self-sufficient energy process based on a biogas plant, renewable energy sources, and energy storage. During the production process, a livestock farm produces large amounts of waste in the form of grey and black manure. On the one hand, these products are highly harmful to the environment, but on the other, they are valuable input products for another process, i.e., methane production. The methane becomes the fuel for cogeneration generators that produce heat and electricity. Heat and electricity are partly returned to the main farming process and partly used by residents of the area. In this way, a livestock farm and the inhabitants of a village or town can become energy self-sufficient and independent of national grids. The idea described in this paper shows the process of energy production combining a biogas plant, renewable energy sources, and an energy storage unit that enable farmland to become fully self-sufficient through the energy flow between all constituents of the energy cycle being maintained by a smart valve.

Muhammad Khalid, Muhammad Usman Khan, Eisha-tul -Razia et al.

Abstract The global need for renewable sources of energy has compelled researchers to explore new sources and improve the efficiency of the existing technologies. Solar energy is considered to be one of the best options to resolve climate and energy crises because of its long-term stability and pollution free energy production. Herein, we have synthesized a small acceptor compound (TPDR) and have utilized for rational designing of non-fullerene chromophores (TPD1–TPD6) using end-capped manipulation in A2–A1–D–A1–A2 configuration. The quantum chemical study (DFT/TD-DFT) was used to characterize the effect of end group redistribution through frontier molecular orbital (FMO), optical absorption, reorganization energy, open circuit voltage (Voc), photovoltaic properties and intermolecular charge transfer for the designed compounds. FMO data exhibited that TPD5 had the least ΔE (1.71 eV) with highest maximum absorption (λ max ) among all compounds due to the four cyano groups as the end-capped acceptor moieties. The reorganization energies of TPD1–TPD6 hinted at credible electron transportation due to the lower values of λ e than λ h . Furthermore, open circuit voltage (Voc) values showed similar amplitude for all compounds including parent chromophore, except TPD4 and TPD5 compounds. These designed compounds with unique end group acceptors have the potential to be used as novel fabrication materials for energy devices.

Tri Hieu Le, Minh Tuan Pham, H Hadiyanto et al.

Passive solar still is the simplest design for distilling seawater by harnessing solar energy. Although it is undeniable that solar still is a promising device to provide an additional freshwater source for global increasing water demand, low thermal efficiency along with daily distillate yield are its major disadvantages. A conventional solar still can produced 2 to 5 L/m2day. Various studies have been carried out to improve passive solar stills in terms of daily productivity, thermal efficiency, and economic effectiveness. Most of the researches that relate to the daily output improvement of passive solar still concentrates on enhancing evaporation or/and condensation processes. While the condensation process is influenced by wind velocity and characteristics of the condensed surface, the evaporation process is mainly affected by the temperature of basin water. Different parameters affect the brackish water temperature such as solar radiation, design parameters (for example water depth, insulators, basin liner absorptivity, reflectors, sun tracking system, etc). The inclined angle of the top cover is suggested to equal the latitude of the experimental place. Moreover, the decrease of water depth was obtained as a good operational parameter, however, the shallow water depth is required additional feed water for ensuring no dry spot existence. Reflectors and sun-tracking systems help solar still absorb as much solar intensity as possible. The internal reflector can enhance daily yield and efficiency of stepped solar still up to 75% and 56% respectively, whereas, passive solar still with the support of a sun-tracking system improved daily yield up to 22%. Despite large efforts to investigate the impact of the different parameters on passive solar distillation, the effect of the basin liner (including appropriate shapes and type of material), needs to be analyzed for improvement in practical utilization. The present work has reviewed the investigation of the solar still performance with various types of basin liner. The review of solar stills has been conducted critically with rectangular basin, fins basin, corrugated basin, wick type, steps shape, and cylindrical shape basin with variety of top cover shapes. The findings from this work conclude that the basin liner with a cylindrical shape had better performance in comparison with other metal types and provides higher freshwater output. Stepped type, inclined, fin absorber, and corrugated shapes had the efficient performance.  Further exploration revealed that copper is the best-used material for the productivity of passive solar still.

Joerg Zotzmann, Alexandra Vetter, Simona Regenspurg

Abstract Reduction or prevention of scaling is commonly achieved by injecting scaling inhibitors into the geothermal circuit. Inhibitor-efficiency tests can be carried out in static or dynamic experiment set-ups allowing measurements at high pressures and high temperatures (HPHT). For these measurements, suitable analytical methods have to be selected depending on the nature of the scales and the specifics of the related sensors in a HPHT environment. In this study, a calcite scaling inhibitor was evaluated in static batch tests at HPHT conditions with respect to its inhibitory efficiency as well as its degradation behaviour. The inhibitor efficiency significantly decreases in comparison to ambient p,T-conditions. In a long-term stability experiment, a delayed partial degradation of the inhibitor at HPHT conditions could be observed.

Nisith Raval, Ajay Kumar Gupta

Sun is the continuous source of renewable energy, from where we can get abundant of solar energy. Concept of conversionof solar energy into heat was used back in 200 B.C. since then, the solar cells have been developed which can convert solar energy into theelectrical energy and these systems have been produced commercially. The technologies to enhance the power conversion efficiency (PCE)have been continuously improved. Different technologies used for developing solar cells can be categorized either on the basis of materialused or techniques of technology development which is further termed as ‘first generation’ (e.g. crystalline silicon), ‘second generation’(thin films of Amorphous silicon, Copper indium gallium selenide, Cadmium telluride), ‘Third generation’ (Concentrated, Organic and Dyesensitize solar cell). These technologies give PCE up to 25% depending on the technology and the materials used. Nanotechnology enablesthe use of nanomaterial whose size is below 100 nm with extraordinary properties which has the capability to enhance the PCE to greaterextent. Various nanomaterials like Quantum Dots, Quantum well, carbon nanotubes, Nanowire and graphene have been used to makeefficient and economical solar cells, which not only provide high conversion efficiency economically but also are easy to produce. Today,by using nanotechnology, conversion efficiency up to 44.7 % has been achieved by Fraunhofer Institute at Germany. In this review article,we have reviewed the literature including various patents and publications, summarized the history of solar cell development, developmentof different technologies and rationale of their development highlighting the advantages and challenges involved in their development forcommercial purpose. We have also included the recent developments in solar cell research where different nanomaterials have beendesigned and used successfully to prove their superiority over conventional systems.