Solar energy—A look into power generation,challenges, and a solar‐powered future

Sun is an inexhaustible source of energy capable of fulfilling all the energy needs of humankind. The energy from the sun can be converted into electricity or used directly. Electricity can be generated from solar energy either directly using photovoltaic (PV) cells or indirectly using concentrated solar power (CSP) technology. Progress has been made to raise the efficiency of the PV solar cells that can now reach up to approximately 34.1% in multi‐junction PV cells. Electricity generation from concentrated solar technologies has a promising future as well, especially the CSP, because of its high capacity, efficiency, and energy storage capability. Solar energy also has direct application in agriculture primarily for water treatment and irrigation. Solar energy is being used to power the vehicles and for domestic purposes such as space heating and cooking. The most exciting possibility for solar energy is satellite power station that will be transmitting electrical energy from the solar panels in space to Earth via microwave beams. Solar energy has a bright future because of the technological advancement in this field and its environment‐friendly nature. The biggest challenge however facing the solar energy future is its unavailability all‐round the year, coupled with its high capital cost and scarcity of the materials for PV cells. These challenges can be met by developing an efficient energy storage system and developing cheap, efficient, and abundant PV solar cells. This article discusses the solar energy system as a whole and provides a comprehensive review on the direct and the indirect ways to produce electricity from solar energy and the direct uses of solar energy. The state‐of‐the‐art procedures being employed for PV characterization and performance rating have been summarized . Moreover, the technical, economic, environmental, and storage‐related challenges are discussed with possible solutions. Furthermore, a comprehensive list of future potential research directions in the field of direct and indirect electricity generation from solar energy is proposed.     

Design considerations and their effects on the operation and maintenance cost in solar‐powered desalination plants

The most critical aspects of any desalination plant are maintenance and operation costs. For solar water desalination, cost reduction and production of superior water quality are still crucial factors that attract researchers. Faults in the design of desalination systems can lead to many maintenance and operational problems in these systems and may lead to increasing water costs and/or decreasing quality of water. This paper offers an analytical study of design considerations and its effects on the operation and maintenance of solar‐powered desalination plants such as plant capacity, location, technology, demands, product water specifications, lifetime, availability, reliability, and input resources. This paper also provides an overview of the factors and components of desalination costs compared with other water supply alternatives and traditional desalination methods; discusses challenges and perceptions; and highlights recent developments in the solar water desalination technology that affect the total cost of water delivery and relationships with operation and maintenance.     

Why self‐cleaning is important for solar thermal receivers?

Surface cleaning remains essential for the sustainable operation of high performance solar thermal receivers. Cleaning of optical surfaces, such as solar troughs and absorbers, requires energy intensive efforts because of the large surface area involvement such as those observed in solar farms. In addition, self‐cleaning of such surfaces becomes demanding because of lowering the cleaning costs, reducing the waste of resources, such as clean water, and minimizing the complication of the mechanical systems incorporated. Self‐cleaning of surfaces is associated with the low adhesion between the surface and the foreign particles; in which case, these particles can be removed easily from the surfaces in a cost‐effective way. The surface energy and contact area of the surface are two main important parameters influencing the particle adhesion on the surfaces. In this case, reducing the surface energy and forming micro/nano size pillars on the surface through texturing lower the particle adhesion on the surfaces significantly. In solar thermal energy harvesting applications, metallic or composite materials are used and texturing the surface remains challenging in terms of cost and precision of operation when conventional texturing methods are used. One of the methods to create surface texture consisting of micro/nano pillars is to use the laser beam ablation. This results in hierarchical distribution of surface texture with desired pillar heights1. In addition, laser surface texturing offers significant advantages over the conventional techniques. Some of these advantages include fast processing, precision of operation, and low cost. Although the laser processing involves with high temperature processing and thermally induced stresses remain important, the defects sites can be minimized via controlling the process parameters during the texturing. Introducing the assisting gas on the texturing surface enables to generate compounds such as oxide or nitride species, which lower the surface energy considerably. Consequently, investigation of laser texturing of solar energy materials while incorporating the assisting gas becomes essential. In the present perspective, the laser surface texturing of solar energy materials for thermal power applications is presented together with challenges and future perspectives. Specifically, the followings will be presented: (1) the texture characteristics of laser treated metallic and ceramic surfaces; (2) wetting state of the textured surface, and optical properties of textured surface in terms of absorption of the solar irradiation.     

A comprehensive optimized model for on‐board solar photovoltaic system for plug‐in electric vehicles: energy and economic impacts

Environmental concerns along with high energy demand in transportation are leading to major development in sustainable transportation technologies, not the least of which is the utilization of clean energy sources. Solar energy as an auxiliary power source of on‐board fuel has not been extensively investigated. This study focuses on the energy and economic aspects of optimizing and hybridizing, the conventional energy path of plug‐in electric vehicles (EVs) using solar energy by means of on‐board photovoltaic (PV) system as an auxiliary fuel source. This study is novel in that the authors (i) modeled the comprehensive on‐board PV system for plug‐in EV; (ii) optimized various design parameters for optimum well‐to‐tank efficiency (solar energy to battery bank); (iii) estimated hybrid solar plug‐in EVs energy generation and consumption, as well as pure solar PV daily range extender; and (iv) estimated the economic return of investment (ROI) value of adding on‐board PVs for plug‐in EVs under different cost scenarios, driving locations, and vehicle specifications. For this study, two months in two US cities were selected, which represent the extremities in terms of available solar energy; June in Phoenix, Arizona and December in Boston, Massachusetts to represent the driving conditions in all the US states at any time followed by assessment of the results worldwide. The results show that, by adding on‐board PVs to cover less than 50% (around 3.2 m²) of the projected horizontal surface area of a typical passenger EV, the daily driving range could be extended from 3.0 miles to 62.5 miles by solar energy based on vehicle specifications, locations, season, and total time the EV remains at Sun. In addition, the ROI of adding PVs on‐board with EV over its lifetime shows only small negative values (larger than ?45%) when the price of electricity remains below Environmental concerns along with high energy demand in transportation are leading to major development in sustainable transportation technologies, not the least of which is the utilization of clean energy sources. Solar energy as an auxiliary power source of on‐board fuel has not been extensively investigated. This study focuses on the energy and economic aspects of optimizing and hybridizing, the conventional energy path of plug‐in electric vehicles (EVs) using solar energy by means of on‐board photovoltaic (PV) system as an auxiliary fuel source. This study is novel in that the authors (i) modeled the comprehensive on‐board PV system for plug‐in EV; (ii) optimized various design parameters for optimum well‐to‐tank efficiency (solar energy to battery bank); (iii) estimated hybrid solar plug‐in EVs energy generation and consumption, as well as pure solar PV daily range extender; and (iv) estimated the economic return of investment (ROI) value of adding on‐board PVs for plug‐in EVs under different cost scenarios, driving locations, and vehicle specifications. For this study, two months in two US cities were selected, which represent the extremities in terms of available solar energy; June in Phoenix, Arizona and December in Boston, Massachusetts to represent the driving conditions in all the US states at any time followed by assessment of the results worldwide. The results show that, by adding on‐board PVs to cover less than 50% (around 3.2 m²) of the projected horizontal surface area of a typical passenger EV, the daily driving range could be extended from 3.0 miles to 62.5 miles by solar energy based on vehicle specifications, locations, season, and total time the EV remains at Sun. In addition, the ROI of adding PVs on‐board with EV over its lifetime shows only small negative values (larger than ?45%) when the price of electricity remains below $0.18/kWh and the vehicle is driven in low‐solar energy area (e.g. Massachusetts in the US and majority of Europe countries). The ROI is more than 148% if the vehicle is driven in high‐solar energy area (e.g. Arizona in the US, most Africa countries, Middle East, and Mumbai in India), even if the electricity price remains low. For high electricity price regions ($0.35/kWh), the ROI is positive and high under all driving scenarios (above 560%). Also, the reported system has the potential to reduce electricity consumption from grid by around 4.5 to 21.0 MWh per EV lifetime. A sensitivity analysis has been carried out, in order to study the impacts of the car parked in the shade on the results. Copyright © 2016 John Wiley & Sons, Ltd.     

A review on copper vanadate‐based nanostructures for photocatalysis energy production

The economic, social, and environmental aspects are important that should be notable before the selection of a method for the production of energy. Various renewable energy sources are used like hydropower, biomass, biofuel, geothermal energy, and wind energy for the production of sustainable energy that are excellent approaches to fulfill energy environmental energy demands. Renewable sources of energy give an excellent chance to extenuate the gas emission in greenhouse and reduction of global warming with the help of renewable sources of energy. The importance and utilization of the variety of renewable sources of energy are elaborated in this article. The emerging and exploring technique for the production of energy is the photocatalysis. In photocatalysis, solar spectrum is the extraneous source that is used with water to produce hydrogen energy (green energy) by the water splitting under the shower of the solar spectrum. The solar spectrum contains heat and intensity of light from which light spectrum is the abundantly used for the splitting of water. The photocatalyst is the key factor to initiate the reaction depending upon the energy band gap by absorbing the energy from the spectrum of the sun. Semiconducting materials having lower forbidden energy band gap are the basic requirements to use them as a photocatalyst for photocatalysis. Copper vanadate and their composites are the promising materials that are used as photocatalyst for the production of hydrogen energy. Copper vanadate is the focusing material that can be used as photocatalyst. It is an n‐type semiconducting material with 2 eV indirect energy band gap having monoclinic structural phase which is tuned by the doping of metals like chromium, molybdenum, and silver to reduce the grain size and energy band gap and increase the surface area and optical absorption of solar light only to enhance the photocatalytic performance towards the production of hydrogen energy by water splitting in the presence of solar light.     

Low‐grade heat‐driven Rankine cycle,a feasibility study

Conversion of low‐grade heat to high‐quality energy such as electricity using the Rankine cycle poses serious challenges. When such conversion is possible, it is invariably expensive or unacceptable due to environmental concerns associated with the working medium. The low‐grade heat can either be from exhaust systems or from solar radiation. Thus, the topic addresses a very useful subject, combining energy efficiency and renewable energy. Although high‐grade heat recovery and energy conversion is a mature technology widely covered by the literature, low‐grade energy conversion, especially using thermodynamic cycles, has not been sufficiently addressed to date. This paper addresses the feasibility of a low‐grade heat‐driven Rankine cycle to produce power using a scroll expander, a low toxicity, low flammability, and ozone‐neutral working fluid. A cost benefit analysis of the recommended system shows that it is a viable option for solar power generation, at about one‐third the cost of a comparable photovoltaic system. Copyright © 2008 John Wiley & Sons, Ltd.     

Simulated production of electric power and desalination using Solar‐OTEC hybrid system

Ocean thermal energy conversion (OTEC) is an electric power generation method that utilizes temperature difference between the warm surface seawater and cold deep seawater of ocean. As potential sources of clean‐energy supply, OTEC power plants' viability has been investigated. However, The OTEC system has problems of low efficiency and high investment cost because the temperature difference between the surface and the deep sea is small and it has a long pipe line and high pumping cost for using cold deep water. Therefore, in this present study, the OTEC system is combined with a solar system. It evaluated the thermodynamic performance of Solar‐OTEC Convergence System for the simultaneous production with electric power and desalinated water. The performance analysis of Solar‐OTEC Convergence System was carried out as the fluid temperature, saturated temperature difference and pressure of flash evaporator under equivalent conditions. The results showed that the performance of solar‐open OTEC system is the highest at the flash evaporator pressure of 10 kPa. At this time, the system efficiency, electric power and desalination production enhancement ratios were approximately 3.9, 13.9 and 5.1 times higher than that of the base open OTEC system respectively. Also, the performance of solar‐hybrid OTEC system is the highest at the inflow fluid temperature of evaporator of 80 °C. The system efficiency, electric power and desalination production enhancement ratios were approximately 3.5, 3.5 and 14.5 times higher than that of the base hybrid OTEC system. Copyright © 2016 John Wiley & Sons, Ltd.     

A hybrid power generation system: solar‐driven Rankine engine–hydrogen storage

This paper reports on the feasibility of a hybrid power generation system consisting of a solar energy‐driven Rankine engine and a hydrogen storage unit. Solar energy, the power for the hybrid system, is converted into electrical power through a combination of a solar collector, a tracking device to maintain proper orientation with the sun and a Rankine cycle engine driving an electrical power generator. Excess electricity is utilized to produce hydrogen for storage through electrolysis of water. At the solar down time, the stored hydrogen can be used to produce high‐quality steam in an aphodid burner to operate a turbine and with a field modulated generator to supplement electric power. Case studies are carried out on the optimum configuration of the hybrid system satisfying the energy demand. A numerical example based on the actual measured solar input is also included to demonstrate the design potential. Copyright © 2001 John Wiley & Sons, Ltd.     

Comprehensive assessment of line‐/point‐focus combined scheme for concentrating solar power system

The line‐/point‐focus combined scheme for concentrating solar power (CSP) system is proposed. For solar field, the parabolic trough (PT) or linear Fresnel (LF) is used as the line‐focus preheating and evaporation stages while the solar tower is used as the point‐focus superheating and reheating stages. The combined schemes benefit from the high concentration ratio of point‐focus technology and low cost of line‐focus technology. Particularly, the combined scheme guarantees the concentrated solar thermal energy matching the temperature requirement of steam generation process with less exergy loss. Performance and economic assessments have been performed for 50 MW_e CSP system with two of the combined schemes, ie, PT (synthetic oil, SO) + Tower (molten salt, MS) and LF (direct steam generation, DSG) + Tower (DSG), as well as existing single schemes being the references, ie, PT (SO), LF (DSG), Tower (MS), and Tower (DSG). The comparative results show that the combined schemes are superior to liner‐focus schemes in efficiency and to point‐focus schemes in capital cost and scalability. Specifically, the PT (SO) + Tower (MS) system suggests the favorable potential in practical application with the highest annual net solar‐to‐electrical energy conversion efficiency of 16.07% and the reasonable levelized cost of electricity (LCOE) of 16.121 US cent/(kW·h). This work provides an alternative guidance for future development of the CSP technology.     

A review on PV cells and nanocomposite‐coated PV systems

Solar radiation can be converted into electrical energy and generate electric power that can be utilized in multiple ways. The technological improvements have provided enormous solutions to the mankind for utilizing the solar energy although photovoltaic's (PV) by consuming sunlight. Photovoltaic is popularly known by the process of converting light to electricity. The current estimated growth by producing global power around 368 GW in 2017 and projecting 3000 to 10 000 GW by 2030. Looking at all the available solar cells, it has been observed that the dye‐sensitized solar cell (DSSC) when compared to mono‐Si or poly‐Si has been effective in its performance and also reduces production cost to a great extent. The power conversion efficiency (PCE) of DSSC has reached to a better extent and been discussed in the paper. There are other mechanisms through which the efficiency can be improved like applying the antireflection coating. Reflection is a usual phenomenon that happens when light incident from one medium to another varies in refractive index. This reflection is one of the important reasons for the loss of power in the PV Cell. So to improve the PCE, the Mono‐Si or DSSC PV Cells can be applied with a thin film antireflection coating by the nanocomposite film consisting of single‐ or multi‐wall carbon nanotubes with TiO₂ and other efficient nanoparticles. This paper discusses on different kinds of nanocomposite materials, and their functionalities has been clearly given. Remarkable improvements have been recorded in the last 1 year by applying the antireflection coating; the PCE has further been increased enormously when compared to the uncoated solar cell for both DSSC and Mono‐Si PV cells.     

Energy‐efficient design of greenhouse for Canadian Prairies using a heating simulation model

Greenhouses in northern climates require a large amount of supplemental heating for growing crops in winter seasons, so energy‐efficient design of greenhouses based on local climate is important to minimize the heating demand. In this study, greenhouse design parameters including shape, orientation, the angle of the roof, and width of the span have been studied for the conceptual design of conventional greenhouses for Canadian Prairies using a heating simulation model. Five different shapes of greenhouses including even‐span, uneven‐span, modified arch, vinery, and quonset shape have been selected for the study. The simulation results proved that the uneven‐span gable roof shape receives the highest solar radiation, whereas the quonset shape receives the lowest solar radiation. However, the quonset shape greenhouse requires about 7.6% less annual heating as compared to the gable roof greenhouse, but the quonset would not be adopted as multispan greenhouses. Therefore, the gable roof greenhouse is considered as energy efficient for the multispan gutter connected greenhouses whereas quonset shape as a free‐standing single‐span greenhouses. In high northern latitudes, the greenhouse with east‐west orientation is more energy efficient from heating and cooling point of view when the length‐width ratio of the greenhouse is more than 1. The heating energy saving potential of the large span width in single‐span greenhouses is relatively higher as compared to the multispan greenhouses.     

Exergetic,environmental and economic analyses of small‐capacity concentrated solar‐driven heat engines for power and heat cogeneration

In this paper, the exergy interactions, environmental impact in terms of CO₂ mitigation, and the economics of small‐capacity concentrated solar power‐driven heat engines for power and heat generation are analysed for residential applications. Starting from a base case study that assumes mass production in Ontario, it is shown that the investment in such a system, making use of a heat engine and having 9 m² of aperture area, could be about CN$10 000 for a peak electrical efficiency of 18% and thermal efficiency of 75%. The average CO₂ mitigation due to combined savings in electricity and heat is ～0.3 kgCO₂ kWh^?1, a figure 3–4 times larger than for photovoltaic panels. If 25% government subsidy to the investment is provided, the payback period becomes 21.6 years. Additionally, if the financing benefits from a feed‐in‐tariff program (at 25% electrical sell‐back to the grid) and deductions from CO₂ tax are realized, then the payback time drops to 11.3 years. These results are obtained for a conservative scenario of 5.5% annual incremental increase in energy price. For the moderate consideration of all factors, it is shown that within the financial savings over the entire lifecycle, 7% are due to carbon tax, 30% are due to electrical production and the largest amount, 63%, is the result of reducing the natural gas heating capacity with solar heating from the proposed system. Copyright © 2011 John Wiley & Sons, Ltd.     

Highly integrated post‐combustion carbon capture process in a coal‐fired power plant with solar repowering

While post‐combustion carbon capture (PCC) technology has been considered as the ready‐to‐retrofit carbon capture solution, the implementation of the technology remains hampered by high costs associated with the large energy penalty incurred by solvent regeneration. This paper presents a highly integrated PCC process for a coal‐fired power plant with solar repowering that features significantly enhanced energy efficiency. Validated process models are developed for the power, capture, and solar thermal plants and simulated in a model superstructure to evaluate the possible improvements in power plant energy efficiency and power output penalty reductions. A 660‐MW power plant is taken as the case study. Three cases are used in this simulation analysis: (a) base case consisting of 660‐MW power plant integrated with a PCC plant, (b) the base case extended to incorporate solar repowering, and (c) a highly integrated case that extends on the previous case to include CO₂ gas compression unit heat integration. This study also highlights and discusses the role and interaction of various PCC and solar plant variables (e.g., solar field size, steam extraction flow rate, and twin LP turbine pressures) in the integration with power plant parameters. In particular, the power plant deaerator conditions play an important role in determining the total solar thermal energy required from the solar plant, thus dictating the solar field size. Copyright © 2015 John Wiley & Sons, Ltd.     

A review on clean energy solutions for better sustainability

This paper focuses on clean energy solutions in order to achieve better sustainability, and hence discusses opportunities and challenges from various dimensions, including social, economic, energetic and environmental aspects. It also evaluates the current and potential states and applications of possible clean‐energy systems. In the first part of this study, renewable and nuclear energy sources are comparatively assessed and ranked based on their outputs. By ranking energy sources based on technical, economic, and environmental performance criteria, it is aimed to identify the improvement potential for each option considered. The results show that in power generation, nuclear has the highest (7.06/10) and solar photovoltaic (PV) has the lowest (2.30/10). When nonair pollution criteria, such as land use, water contamination, and waste issues are considered, the power generation ranking changes, and geothermal has the best (7.23/10) and biomass has the lowest performance (3.72/10). When heating and cooling modes are considered as useful outputs, geothermal and biomass have approximately the same technical, environmental, and cost performances (as 4.9/10), and solar has the lowest ranking (2/10). Among hydrogen production energy sources, nuclear gives the highest (6.5/10) and biomass provides the lowest (3.6/10) in ranking. In the second part of the present study, multigeneration systems are introduced, and their potential benefits are discussed along with the recent studies in the literature. It is shown that numerous advantages are offered by renewable energy‐based integrated systems with multiple outputs, especially in reducing overall energy demand, system cost and emissions while significantly improving overall efficiencies and hence output generation rates. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel glazing technologies to mitigate energy consumption in low‐carbon buildings: a comparative experimental investigation

Buildings play a key role in total world energy consumption as a consequence of poor thermal insulation characteristics of facade materials. Among the elements of a typical building envelope, windows are responsible for the greatest energy loss because of their notably high overall heat transfer coefficients. About 60% of heat loss through the building fabric can be attributed to the glazed areas. In this respect, novel cost‐effective glazing technologies are needed to mitigate energy consumption, and thus to achieve the latest targets toward low/zero carbon buildings. Therefore in this study, three unique glazing products called vacuum tube window, heat insulation solar glass and solar pond window which have recently been developed at the University of Nottingham are introduced, and thermal performance analysis of each glazing technology is done through a comparative experimental investigation for the first time in literature. Standardized co‐heating test methodology is performed, and overall heat transfer coefficient (U‐value) is determined for each glazing product following the tests carried out in a calibrated environmental chamber. The research essentially aims at developing cost‐effective solutions to mitigate energy consumption because of windows. The results indicate that each glazing technology provides very promising U‐values which are incomparable with conventional commercial glazing products. Among the samples tested, the lowest U‐value is obtained from the vacuum tube window by 0.40 W/m²K, which corresponds to five times better thermal insulation ability compared to standard air filled double glazed windows. Copyright © 2015 John Wiley & Sons, Ltd.     

A review on thermal energy storage systems in solar air heaters

The drying needs of agricultural, industrial process heat requirements and for space heating, solar energy is one of the prime sources which is renewable and pollution free. As the solar energy is inconsistent and nature dependent, more often there is a mismatch between the solar thermal energy availability and requirement. This drawback could be addressed to an extent with the help of thermal energy storage systems combined with solar air heaters. This review article focuses on solar air heaters with integrated and separate thermal energy storage systems as well as greenhouses with thermal storage units. A comprehensive study was carried out in solar thermal storage units consisting of sensible heat storage materials and latent heat storage materials. As the phase change heat storage materials offer many advantages over the sensible heat storage materials, the researchers are more interested in this system. The charging and discharging characteristics of thermal storage materials with various operational parameters have been reported. All the possible solar air heater applications with storage units have also been discussed.     

Review of photocatalytic water‐splitting methods for sustainable hydrogen production

This paper examines photocatalytic hydrogen production as a clean energy solution to address challenges of climate change and environmental sustainability. Advantages and disadvantages of various hydrogen production methods, with a particular emphasis on photocatalytic hydrogen production, are discussed in this paper. Social, environmental and economic aspects are taken into account while assessing selected production methods and types of photocatalysts. In the first part of this paper, various hydrogen production options are introduced and comparatively assessed. Then, solar‐based hydrogen production options are examined in a more detailed manner along with a comparative performance assessment. Next, photocatalytic hydrogen production options are introduced, photocatalysis mechanisms and principles are discussed and the main groups of photocatalysts, namely titanium oxide, cadmium sulfide, zinc oxide/sulfide and other metal oxide‐based photocatalyst groups, are introduced. After discussing recycling issues of photocatalysts, a comparative performance assessment is conducted based on hydrogen production processes (both per mass and surface area of photocatalysts), band gaps and quantum yields. The results show that among individual photocatalysts, on average, Au–CdS has the best performance when band gap, quantum yield and hydrogen production rates are considered. From this perspective, TiO₂–ZnO has the poorest performance. Among the photocatalyst groups, cadmium sulfides have the best average performance, while other metal oxides show the poorest rankings, on average. Copyright © 2016 John Wiley & Sons, Ltd.     

Parametric analysis and yearly performance of a trigeneration system driven by solar‐dish collectors

Solar‐driven polygeneration systems are promising technologies for covering many energy demands with a renewable and sustainable way. The objective of the present work is the investigation of a trigeneration system, which is driven by solar‐dish collectors. The examined trigeneration system includes an organic Rankine cycle (ORC), which operates with toluene, and an absorption heat pump, which operates with LiBr/H₂O. The absorption heat pump is fed with heat by the condenser of the ORC, which operates at medium temperature levels (120°C to 150°C). The absorption heat pump produces both useful heat at 55°C and cooling at 12°C. The ORC produces electricity, and it is fed by the solar dishes. The examined ORC is a regenerative cycle with superheating. The total analysis is performed with a developed model in Engineering Equation Solver (EES). The system is investigated parametrically for different ORC heat‐rejection temperatures, different superheating levels in the turbine inlet, and various solar‐beam irradiation levels. Furthermore, the system is investigated on a yearly basis for the climate conditions of Athens (Greece) and for Belgrade (Serbia). It is found that the yearly system energy and exergy efficiencies are 108.39% and 20.92%, respectively, for Athens, while 111.38% and 21.50%, respectively, for Belgrade. The values over 100% for the energy efficiency are explained by the existence of a heat pump in the examined configuration. For both locations, the payback period is found close to 10 years and the internal rate of return close to 10%. The final results indicate that the examined configuration is a highly efficient and viable system, which operates only with a renewable energy source.     

Year around distilled water production,energy, and economic analysis of solar stills—A comparative study

In this paper, a year around energy efficiency (EnE) and economic analysis of single slope solar still (SSSS), the single slope solar still with glass cooling (SSSSGC), the single slope solar still with basin heating (SSSSBH), and the single slope solar still with glass cooling and basin heating (SSSSGCBH) was carried out based on the distilled water production. The annual yield production from the SSSS, SSSSGC, SSSSBH, and SSSSGCBH were 476.16, 637.44, 970.24, and 1167.36 kg, respectively. The yearly yield produced from the SSSSBH and SSSSGCBH was increased by 50.92% and 59.21%, respectively, as compared with the SSSS. Moreover, the annual EnE of the SSSSGCBH was 28.75%. However, the EnE of the SSSS was 11.73%. Also, freshwater making cost is found to be 18.9, 24.9, 37.9, and 45.6 Rs/day for the SSSS, SSSSGC, SSSSBH, and SSSSGCBH, respectively, if the buying cost of freshwater is Rs 10.     

Design and analysis of an integrated concentrated solar and wind energy system with storage

This study analyzes a renewable energy‐driven innovative multigeneration system, in which wind and solar energy sources are utilized in an efficient way to generate several useful commodities such as hydrogen, oxygen, desalted water, space cooling, and space heating along with electricity. A 1‐km² heliostat field is considered to concentrate the solar light onto a spectrum splitter, where the light spectrum is separated into two portions as reflected and transmitted to be used as the energy source in the concentrated solar power (CSP) and concentrated photovoltaics (CPV) receivers, respectively. As such, CSP and CPV systems are integrated. Wind energy is proposed for generating electricity (146 MW) or thermal energy (138 MW) to compensate the energy need of the multigeneration system when there is insufficient solar energy. In addition, multiple commodities, 46 MW of electricity, 12 m³/h of desalted water, and 69 MW of cooling, are generated using the Rankine cycle and the rejected heat from its condenser. Further, the heat generated on CPV cells is recovered for efficient photovoltaic conversion and utilized in the space heating (34 MW) and proton exchange membrane (PEM) electrolyzer (239 kg/h) for hydrogen production. The energy and exergy efficiencies of the overall system are calculated as 61.3% and 47.8%, respectively. The exergy destruction rates of the main components are presented to identify the potential improvements of the system. Finally, parametric studies are performed to analyze the effect of changing parameters on the exergy destruction rates, production rates, and efficiencies.