Renewable and Sustainable Energy Systems

The main objective of this study is to develop single location appropriate models for the estimation of the monthly average daily global and diffuse horizontal solar radiation for Brasov, Romania. The study focuses particularly on models based on the sunshine duration and clearness index. The data used for the calibration of the models were collected during a period of 4 yr, between November 2008 and October 2012, at the Transilvania University of Brasov. The testing and validation of the models was carried out using data from the online SoDa database for Brasov for the year 2005. Different statistical error tests were applied to evaluate the accuracy of the models. The predicted values are also compared with values from three other known models concerning the global and diffuse solar radiation. A new mixed model was developed for the estimation of monthly average daily global horizontal solar radiation. The data processing was performed by means of a realtime interface developed with LabVIEW graphical programming language. The parameters taken into account were the relative sunshine, the clearness index, the extraterrestrial radiation, the latitude and the longitude. The methodology is simple and effective and may be applied for any region. Its effectiveness was proven through comparison with global models. V

The present rate of economic growth is unsustainable without saving of fossil energy like crude oil, natural gas or coal. Thus mankind has to rely on the alternate/renewable energy sources like biomass, hydropower, geothermal energy, wind energy, solar energy, nuclear ...

Despite the increasing number of small scale digesters operating, there remains a lack of information with regards to performance optimization from an everyday user's standpoint. The objective of this study was to determine the effects of volumetric dilution and food waste composition on digester performance. Batch experiments utilizing food waste majoring in carbohydrate, protein, lipid, and cellulose, subjected to five concentrations of volumetric dilution (3.7%-17.1% total solids (TS)), were conducted. Irregardless of volumetric dilution, all assays achieved substrate degradation higher than 82.5% and did not suffer methanogenic inhibition, when provided with retention times comparable to those used in small scale digesters. Protein rich and cellulose rich waste achieved the highest methane potential varying between 0.410-0.539 m 3 /kg volatile solids (VS) and 0.450-0.535 m 3 /kg VS, respectively. Protein rich assays were also observed to be the first to achieve 50% of its Bo irregardless of concentrations, followed by carbohydrates and cellulose, and lipids having a considerably longer methanation time. Results saw an increase in total methane generated but a decrease in specific yield as % total solid increased. To successfully digest lipid rich waste a dilution no lesser than 1:4 was required.

Artificial intelligence (AI) techniques are becoming useful as alternate approaches to conventional techniques or as components of integrated systems. They have been used to solve complicated practical problems in various areas and are becoming more and more popular nowadays. AItechniques have the following features: can learn from examples; are fault tolerant in the sense that they are able to handle noisy and incomplete data; are able to deal with non-linear problems; and once trained can perform prediction and generalization at high speed. AI-based systems are being developed and deployed worldwide in a myriad of applications, mainly because of their symbolic reasoning, flexibility and explanation capabilities. AI have been used and applied in different sectors, such as engineering, economics, medicine, military, marine, etc. They have also been applied for modeling, identification, optimization, prediction, forecasting, and control of complex systems. The main objective of this paper is to present an overview of the AI-techniques for sizing photovoltaic (PV) systems: stand-alone PVs, grid-connected PV systems, PV-wind hybrid systems, etc. Published literature presented in this paper show the potential of AI as a design tool for the optimal sizing of PV systems. Additionally, the advantage of using an AI-based sizing of PV systems is that it provides good optimization, especially in isolated areas, where the weather data are not always available. #

Wind energy, with an average growth rate of 30%, is the fastest growing source of renewable energy in the world. India occupies the fifth place in the world in wind energy generation after USA, Germany, Spain, and China and has an installed capacity of more than 9756 MW as of January 31, 2009. New technological developments in wind energy design have contributed to the significant advances in wind energy penetration and to get optimum power from available wind. In this study, an attempt has been made to analyze and review the development and dissemination of wind energy in India. The diffusion prospect of wind energy generation in the potential states of India is also analyzed.

The results of a numerical simulation of the current distribution of a three-dimensional, tubular shaped, proton exchange membrane fuel cell model are presented. An integrated flow and current density model to predict current density distributions in two dimensions along the membrane has been developed. The numerical model has a cylindrical geometry that includes diffusion layers on the anode and cathode side, the anode being the inner most electrode, and solves the same primary flow related variables along the channels and the diffusion layers. The simulation was performed with commercial flow solver software where a control volume approach was used and source term equations that characterize the electrochemical aspects of the fuel cell have been added.

Natural convection or buoyancy-driven heat transfer in triangular shaped cavities (enclosures) is a heat transfer field of major significance in applications such as in the design of green houses, pitched roofs or attics etc. In this study, the natural convection heat transfer performance was investigated in a triangular enclosure with an inner cylinder containing water as working medium. A finite-volume based numerical tool, that is, ANSYS FLUENT 18.1, was used for the numerical analysis of the governing fluid flow equations. A series of governing variables including Rayleigh number and cylinder diameter were studied. Results showed that the natural convection heat transfer in the enclosure reduces gradually with increasing cylinder diameter. Furthermore, the extent to which the Rayleigh number affects the thermal resistance posed by the enclosure and the optimal cylinder diameter was also studied.

Economic and environmental concerns over fossil fuels encourage the development of photovoltaic (PV) energy systems. The aim of this paper is to evaluate the effect of orientation angles on the output power of a PV panel, thereby harnessing more of the available solar energy. The practical setup consists of a number of identical PV systems where the PV panels were set to an orientation angle of 0 N, þ15 W, and À15 E, with a constant tilt angle of 36 . Tilt and orientation angles play a major role in dictating the output power of a PV panel and subsequently on the power fed into the respective load within the PV system. Preliminary results, which include percentages showing when the system was fully charged and the work-time per day, indicate that a 0 N orientation angle produces the highest amount of output power for a latitude of 26 S. V C 2014 AIP Publishing LLC.

An energy resource that is renewed by nature and whose supply is not affected by the rate of consumption is often termed as renewable energy. The need to search for renewable, alternate and non-polluting sources of energy assumes top priority for self-reliance in the regional energy supply. This demands an estimation of available energy resources spatially to evolve better management strategies for ensuring sustainability of resources. The spatial mapping of availability and demand of energy resources would help in the integrated regional energy planning through an appropriate energy supply-demand matching. This paper discusses the application of Geographical Information System (GIS) to map the renewable energy potential talukwise in Karnataka State, India. Taluk is an administrative division in the federal set-up in India to implement developmental programmes like dissemination of biogas, improved stoves, etc. Hence, this paper focuses talukwise mapping of renewable energy (solar, wind, bioenergy and small hydroenergy) potential for Karnataka using GIS. GIS helps in spatial and temporal analyses of the resources and demand and also aids as Decision Support System while implementing location-specific renewable energy technologies.

... Upon implementation of provisions set forth by the Law on Radioactive Waste Management ... electricity generation at power plants taking into account additional electricity demand for CCS. ... for these technologies assessment is obtained from EU Framewok 6 project NEEDS and ...

An overview of standby power management in electrical and electronic power devices and appliances to improve the overall energy efficiency in creating a green world J. Renewable Sustainable Energy 3, 023112 Performance and applicability of a dc refrigerator powered by the photovoltaics J. Renewable Sustainable Energy 2, 013101 (2010)

Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst. The process of transesterification is affected by the mode of reaction condition, molar ratio of alcohol to oil, type of alcohol, type and amount of catalysts, reaction time and temperature and purity of reactants. In the present paper various methods of preparation of biodiesel with different combination of oil and catalysts have been described. The technical tools and processes for monitoring the transesterification reactions like TLC, GC, HPLC, GPC, 1 H NMR and NIR have also been summarized. In addition, fuel properties and specifications provided by different countries are discussed.

Photocatalysis process, as an environmental application, is a relatively novel subject with tremendous potential in the near future. A number of studies determine the economic viability of applying various ultraviolet advanced oxidation processes for the purpose of degradation and destroying of various pollutant solutions. The present paper reviews the treatment of hazardous wastewater bearing organic compounds and the effects of various parameters such as pH, initial concentration, mass of catalyst, wavelength, light intensity, electron acceptor, temperature, etc., with the treatment cost for different reactor type. This study investigates the effect of various types of waste-water treatment parameters and the treatment cost for various designs of photocatalytic reactors, using both solar and artificial light, have been proposed for their different types of pollutants.

Floating photovoltaic (FPV) technology is gaining prominence as a means to alleviate land use conflicts while obtaining large solar PV deployments and simultaneously reducing evaporated water loss. In this study, an open source after-market distributed manufacturing method is proposed to be applied to large flexible PV modules to make flexible FPV systems. Specifically this study considers surface floating of flexible thin film solar PV using three types of closed-cell foams: i) neoprene, ii) mincell and iii) polyethylene. The fabricated FPV underwent indoor and outdoor tests for flotation, wave resistance, temperature and resistance to algae accumulation. The average operational temperature was reduced by 10-20 o C for the FPV compared to land-based mounting indicating substantial increases in electricity output compared to ground-based deployment of any type of PV (2-4% for amorphous silicon used here and 5-10% for crystalline Si based PV). In addition, foam-based FPV racking were also found to reduce costs of racking to $0.37-0.61/W, which is significantly lower than raft-based FPV as well as conventional land-based racking. The results of this preliminary study indicate that foam-backed FPV is exceptionally promising and should be further investigated with different foams, larger systems and more diverse deployments for longer periods to increase PV deployments.

Renewable energy is the inevitable choice for sustainable economic growth, for the harmonious coexistence of human and environment as well as for the sustainable development. Government support is the key and initial power for developing renewable energy. In this article, an overall review has been conducted on renewable energy development policy (including laws and regulations, economic encouragement, technical research and development, industrialized support and government model projects, etc.) in China. On this basis, a systematic analysis has been conducted on the disadvantages of renewable energy development policy. On the point of long-term effective system for renewable energy development, a series of policy advice has been offered, such as strengthening the policy coordination, enhancing regional policy innovation, echoing with clean development mechanism, implementing process management, constructing market investment and financing system. It is expected that the above advices could be helpful to ever-improvement of renewable energy development policy. #

Life Cycle Analyses (LCA) are used to compare biofuels to fossil fuels. These analyses are made according to the ISO 14040-43 standards, which using a defined unit compare mass and energy balances for two or more comparison objects.In Spain, the Spanish government Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, CIEMAT, has performed two LCA's in order to compare ethanol and ethanol mixtures with unleaded gasoline and biodiesel and biodiesel mixtures with fuel-oil according to these standards. Both LCA's conclude that biofuels require less primary energy than fossil fuels to be processed and that CO2 emissions are lower when using biofuels instead of fossil fuels.However, these LCA's have been strongly criticized for several reasons. This report presents a new LCA model which allows the comparison of biofuels and fossil fuels based on the maximisation and optimisation of production resources avoiding the disadvantages of the traditional LCA model based on the ISO 14040-43 standards.

This presentation proposes the most feasible configuration of solar PV system with diesel generator as back up for typical estate electrification in Lagos-solar PV hybrid system. Integration of PV systems with the diesel plants as backup is being disseminated worldwide to reduce diesel fuel consumption and to minimize atmospheric pollution. The proposed simulation has been done to assure that the PV-Diesel hybrid system is economically and technically feasible. Technical and economic analysis of the optimum system has been done to compare the economic viability of solar photovoltaic (PV)/ gen/battery hybrid power system with that of a standalone diesel generator only system. For analysis purposes HOMER simulation software has been used and meteorological data of solar insolation of the site have been taken from online data from NASA. To incorporate uncertainty in solar radiation and diesel fuel price, both are taken as a sensitivity variable in the simulation. The costs of components are taken from the online site of manufacturing and equipment suppliers and adjusted to Nigeria price value. The result of simulation shows that solar PV system with Generator backup is more cost effective and environmental friendly over the conventional sole diesel generator system within life time of the project (24 years).

The continuous search for sustainable alternative  energy to non renewable energy to mitigate environmental pollution has made waste heat recovery from industries process, material and energy streams frontier. Power  plant technologies like steam and  Organic Rankine cycle are been  research  by  researchers  to  improve  waste  heat  recovery efficiency  and  energy utilization. In this study Hexane and Toluene are the organic fluid used .Their performance inwaste  heat  recovery  in  the  melting  furnace  of  a  Sulphuric  Acid plant  was  compared  with conventional  Steam  Rankine  cycle.  Energetic  and  Exergetic  analysis  was  carried  out  to investigate  the  performance  of  Steam  and  Organic  Rankine  cycle for  waste  heat  recovery temperature less than 200oC.  In the ORC ,Hexane and Toluene has over all system efficiency 90.7% and 82% respectively while SRC has 81% .The energy efficiency result was supported by Exergetic efficiency where SRC has the lowest Exergy Efficiency of 74% while  those of Hexane and Toluene were  88%, 84% respectively.  The energy efficiency revealed that ORC has  a  better  waste  heat  energy  utilization  performance  at  low  temperature  when  compared with  SRC.  Furthermore,  Hexane  has  the  highest  power  generation  of  4.74  MW  from  low grade heat source of 200oC. It is therefore recommended that Hexane should be considered as a working fluid in harnessing waste heat energy using Organic Rankine Cycle.

H-Darrieus rotor is a lift type device having two to three blades designed as airfoils. The blades are attached vertically to the central shaft through support arms. The support to vertical axis helps the rotor maintain its shape. In this paper, Computational Fluid Dynamics (CFD) analysis of an airfoil shaped twobladed H-Darrieus rotor using Fluent 6.2 software was performed. Based on the CFD results, a comparative study between experimental and computational works was carried out. The H-Darrieus rotor was 20cm in height, 5cm in chord and twisted with an angle of 30° at the trailing end. The blade material of rotor was Fiberglass Reinforced Plastic (FRP). The experiments were earlier conducted in a subsonic wind tunnel for various height-to-diameter (H/D) ratios. A two dimensional computational modeling was done with the help of Gambit tool using unstructured grid. Realistic boundary conditions were provided for the model to have synchronization with the experimental conditions. Two dimensional steady-state segregated solver with absolute velocity formulation and cell based grid was considered, and a standard k-ε viscous model with standard wall functions was chosen. A first order upwind discretization scheme was adopted for pressure velocity coupling of the flow. The inlet velocities and rotor rotational speeds were taken from the experimental results. From the computational analysis, power coefficient (C p ) and torque coefficient (C t ) values at ten different H/D ratios namely 0.85, 1.0, 1.10, 1.33, 1.54, 1.72, 1.80, 1.92, 2.10 and 2.20 were calculated in order to predict the performances of the twisted H-rotor. The variations of C p and C t with tip speed ratios were analyzed and compared with the experimental results. The standard deviations of computational C p and C t from experimental C p and C t were obtained. From the computational analysis, the highest values of C p and C t were obtained at H/D ratios of 1.0 and 1.54 respectively. The deviation of computational C p from experimental C p was within ± 2.68%. The deviation of computational C t from experimental C t was within ± 3.66%. Thus, the comparison between computational works and experimental works is quite encouraging.

This paper elucidates the maximum methyl ester conversion from free fatty acids of Punnai oil by acid-base catalyst. Conjointly performance emission and combustion characteristics of Punnai Methyl Ester biodiesel and its blends are discussed in detail. It was evident from the study that the maximum Free Fatty Acids to Fatty Acids of Methyl Esters conversion of around 93.4% was obtained by using heterogeneous catalyst. Concentrated sulphuric acid (H 2 SO 4) and sodium hydroxide (NaOH) were used as a heterogeneous catalyst in the study to reduce the structural properties of untainted punnai oil. Brake Thermal Efficiency, Brake Specific Fuel Consumption, and Combustion Analysis were noted to be not much affected up to B30 blend. Lower CO and HC for Biodiesel-diesel blend were noted in the experimental study. In contrary, CO 2 , NO x , and smoke opacity showed an opposite trend, whose values increased with increase in biodiesel-diesel blends.

Sustainable production of renewable energy is being hotly debated globally since it is increasingly understood that first generation biofuels, primarily produced from food crops and mostly oil seeds are limited in their ability to achieve targets for biofuel production, climate change mitigation and economic growth. These concerns have increased the interest in developing second generation biofuels produced from non-food feedstocks such as microalgae, which potentially offer greatest opportunities in the longer term. This paper reviews the current status of microalgae use for biodiesel production, including their cultivation, harvesting, and processing. The microalgae species most used for biodiesel production are presented and their main advantages described in comparison with other available biodiesel feedstocks. The various aspects associated with the design of microalgae production units are described, giving an overview of the current state of development of algae cultivation systems (photo-bioreactors and open ponds). Other potential applications and products from microalgae are also presented such as for biological sequestration of CO2, wastewater treatment, in human health, as food additive, and for aquaculture.

X-ray machines are usually provided with a beam restriction system (or collimator) to regulate the size of the X-ray field. This restriction system plays a significant role in patient's dose as it is used to identify and restrict the X-ray field to desired scan area. To collimate X-ray field to the correct size and position, a light beam is projected through the X-ray collimator to coincide with the X-ray field. Thus, the X-ray beam is simulated by the light beam and allows the technologist to identify and collimate the X-ray beam to desired scan area. Misalignment between the light field and the X-ray field may result in an unnecessary exposure or repeated exposure. It is very important to ensure that the X-ray field is perpendicular to the plane of the image receptor and that the image receptor is centred to the X-ray field. Improper perpendicularity between the X-ray beam and the image receptor may result in an image distortion and loss of resolution. This test was conducted at 100cm SID, 8kvp, 10mAs and large focal spot. The maximum outside and inside misalignment ratios were 0.0% and 1.5% of the SID respectively. The displacement error between the X-ray field and the image receptor was 1.2 cm, which is equivalent to 1.2% of the SID. The X-ray beam was found to be perpendicular to the image receptor to about 1.7 0. For the beam alignment test of an X-ray machine to read positive, it must pass all the tests, and the beam alignment be 1.5 0. The beam alignment of this machine was found to be faulty as it did not pass all the alignment tests.

Thermal energy storage in general, and phase change materials (PCMs) in particular, have been a main topic in research for the last 20 years, but although the information is quantitatively enormous, it is also spread widely in the literature, and difficult to find. In this work, a review has been carried out of the history of thermal energy storage with solid-liquid phase change. Three aspects have been the focus of this review: materials, heat transfer and applications. The paper contains listed over 150 materials used in research as PCMs, and about 45 commercially available PCMs. The paper lists over 230 references.

The increasingly manifest impacts of global warming have made it a global priority to phase out the use of petrol and diesel as transportation fuels in favour of hydrogen. But the production of hydrogen by most existing technologies entails substantial use of fossil fuels and CO 2 emissions; indeed as much as 2.5-5 tonnes of carbon is released as CO 2 per tonne of hydrogen currently produced by conventional means. Hence the production of hydrogen can be 'carbon-free' only if it is generated by employing genuinely carbon-free renewable energy sources.

This paper presents a detailed review of effect of phase change material (PCM) encapsulation on the performance of a thermal energy storage system (TESS). The key encapsulation parameters, namely, encapsulation size, shell thickness, shell material and encapsulation geometry have been investigated thoroughly. It was observed that the core-to-coating ratio plays an important role in deciding the thermal and structural stability of the encapsulated PCM. An increased core-to-coating ratio results in a weak encapsulation, whereas, the amount of PCM and hence the heat storage capacity decreases with a decreased core-to-coating ratio. Thermal conductivity of shell material found to have a significant influence on the heat exchange between the PCM and heat transfer fluid (HTF). This paper also reviews the solidification and melting characteristics of the PCM and the effect of various encapsulation parameters on the phase change behavior. It was observed that a higher thermal conductivity of shell material, a lower shell size and high temperature of HTF results in rapid melting of the encapsulated PCM. Conduction and natural convection found to be dominant during solidification and melt processes, respectively. A significant enhancement in heat transfer was observed with microencapsulated phase change slurry (MPCS) due to direct surface contact between the encapsulated PCM and the HTF. It was reported that the pressure drop and viscosity increases substantially with increase in volumetric concentration of the microcapsules.

‘Green retrofits’ are any kind of upgrade at an existing building that is wholly or partially occupied to improve energy and environmental performance, reduce water use, and improve the comfort and quality of the space in terms of natural light, air quality, and noise-all done in a way that is financially beneficial to the owner. However the application of Green Retrofits is a process that has to be
designed to especially pertain to various aspects of a building like its age and its climatic positioning. Retrofitting can be carried out for an entire building or for one or more working systems of a building in order to improve a its operations and maintenance (O&M) procedures to enhance overall building performance. This study examines the scope for developing Delhi as a Green Capital through retrofits, highlighted by examples of existing models, and the role of
Government Policy making in promoting sustainability.
Through an interdisciplinary framework of economic, demographic, climatic
and architectural studies the paper provides a holistic view of the Country’s
capacity and challenges in Greening Delhi through retrofitting. Using in depth analysis of Green Rating Systems and the role of Energy Servicing Companies,
this study traces the possibility of developing Delhi as a Green Capital through Retro commissioning corroborated by Government policies with consideration
for its existing structural model and climatic conditions. The study concludes that Green building practices can be promoted in Delhi by the central government providing incentives and issuing mandates for adopting sustainable building codes and the State government and Municipality taking initiatives
to enforce them. It also highlights the role of private and public stakeholders and the importance of awareness about Green Building Practices amongst developers and communities.