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Abstract The Paris Agreement aims to combat climate change by keeping a global temperature rise this century well below 2oC by the reduction of CO 2 production. Scotland aims to be a world leader in the change and has set ambitious targets to meet this commitment. With nearly 70% of the energy cost in the production of ice cream spent on refrigeration, any improvement in their efficiency will reduce energy costs and CO 2 production. A waste heat recovery system presents a great opportunity to reclaim energy from the onsite refrigeration systems and convert it into useful hot water. A £216,275 project funded by The Engineering and Physical Sciences Research Council and Innovate UK was setup to investigate the use of a waste recovery system within an onsite refrigeration system. The results showed a savings of 5% by the refrigeration plant in total along with an individual saving of 27% by the compressor within the refrigeration system. The WHRS also produced a supply of hot water which could be used onsite within the manufacturing or cleaning processes required onsite. [ABSTRACT FROM AUTHOR]

Integrated collector storage is a long established simple low cost solar water heater configuration combining the solar collector with a storage tank into a single unit. Previous studies have shown the potential of integrated collector storage solar water heaters to significantly reduce domestic energy requirements for water heating, however challenges still remain to integrate them in roof/façades and ensure appropriate domestic hot water demand. In this article, a novel integrated collector storage solar water heaters is being investigated. The configuration and geometry proposed incorporates an embedded heating element to provide a self-contained domestic hot water system and consider roof integration restriction allowing the unit to be embedded within a structural insulated roofing panel system. The proposed system also utilizes an inlet diffuser designed to reduce the disruption to the stratification within the storage during and following draw-off. This article presents a Computational Fluid Dynamic analysis of internal flows and heat transfer regimes within this new collector configuration and compares its performance against previous developed prototypes using empirical testing. The increased aspect ratio of the new design was shown to significantly alter the heating and cooling characteristics of the collector, both gaining and loosing heat at a greater rate than the original prototype. The computational analysis showed that the collector charges effectively with some stratification. Higher draw-off rates however resulted in higher bulk water outlet temperatures, providing better energy delivery efficiency. The inlet diffuser was also shown to improve the thermal efficiency of the unit overall. The empirical testing shows the improvement in performance of this novel integrated collector storage solar water heaters against previous developed prototypes. The study highlights the need to review the effect of draw-off regime upon the performance of such systems in order to identify optimal regime and control strategy. [ABSTRACT FROM AUTHOR]

Fuelled by a rapidly rising human global population, an increasing demand for freedom to travel and the affordability made possible by modern manufacturing there has been an exponential rise in the number of automobiles – in the year 2013 there were in excess of a billion automobiles in use! Three factors that are of serious concern are the consequential energetic, environmental and economic impacts. One solution that is being seen by a number of national governments is the advent (or rather re-introduction) of electric vehicles (EVs). However, one of the key factors that will need to be explored will be the source of the required electricity for the EVs that will define the level of their sustainability. In this article an experimental evaluation of an electric vehicle has been undertaken. The Renault Zoe e-car has been used for this task with the ‘car chasing’ technique employed to measure the driving cycle. The speed and energy use were recorded for the vehicle that was driven along the principal arteries of the City of Edinburgh, Scotland. In a separate activity vehicle driving tests were also undertaken in one town in Slovenia (Celje). In both places urban and suburban routes were covered for different times of the day. Results are presented to quantify the energetic, environmental and economic performance indices for the driven vehicle. A discussion is also provided on the potential for reduction of carbon emissions from the transport sector by provision of environmentally-friendly means of generating electricity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Driving cycle measurements. [•] Estimation of vehicular driving patterns in the Slovenian city of Celje. [•] Comparison with the driving cycles of other cities in Europe. [Copyright &y& Elsevier]

Abstract: The receiving ends of the solar energy conversion systems that generate heat or electricity from radiation is usually tilted at an optimum angle to increase the solar incident on the surface. Solar irradiation data measured on horizontal surfaces is readily available for many locations where such solar energy conversion systems are installed. Various equations have been developed to convert solar irradiation data measured on horizontal surface to that on tilted one. These equations constitute the conventional approach. In this article, an alternative approach, generalized regression type of neural network, is used to predict the solar irradiation on tilted surfaces, using the minimum number of variables involved in the physical process, namely the global solar irradiation on horizontal surface, declination and hour angles. Artificial neural networks have been successfully used in recent years for optimization, prediction and modeling in energy systems as alternative to conventional modeling approaches. To show the merit of the presently developed neural network, the solar irradiation data predicted from the novel model was compared to that from the conventional approach (isotropic and anisotropic models), with strict reference to the irradiation data measured in the same location. The present neural network model was found to provide closer solar irradiation values to the measured than the conventional approach, with a mean absolute error value of 14.9Wh/m2. The other statistical values of coefficient of determination and relative mean absolute error also indicate the advantage of the neural network approach over the conventional one. In terms of the coefficient of determination, the neural network model results in a value of 0.987 whereas the isotropic and anisotropic approaches result in values of 0.959 and 0.966, respectively. On the other hand, the isotropic and anisotropic approaches give relative mean absolute error values of 11.4% and 11.5%, respectively, while that of the neural network model is 9.1%. [Copyright &y& Elsevier]

This paper analyses and compares the performance between a bifacial and a monofacial PV system based on the tests conducted at Heriot-Watt University, UK. The module's performance was observed on different ground reflective surfaces: concrete, white tiles, soil, and white pebbles. The rear side irradiance and bifacial energy gains are analysed. The power output is examined for a sunny and cloudy days, and yearly energy mapping is shown. Correlation studies are performed, and empirical model are developed between (i) clearness index and rear irradiance gain: (ii) rear irradiance gain and bifacial energy gain; (iii) total irradiance and power output. Based on the annual rear irradiance gain analysis, the highest gain range is found for white pebbles and white tiles ground surface (>30 % gain) and lowest for soil surface within the 5 %–10 % range and for concrete, >20 %. Regardless of the ground reflective surface, the probability is low that the bifacial energy gain is more than 30 %. Finally, a case study is discussed to perform a sensitivity analysis of a bifacial PV project's Levelized cost of electricity (LCOE). The sensitivity analysis shows that by using an enhanced ground albedo surface, the LCOE of the bifacial PV project can be reduced to 7.15p/kWh. The results show consistency with simulations output ran in PVSyst for different locations across the UK and the reported bifacial gain worldwide. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an analysis of vehicle regenerative braking systems as a quick and relatively easy means of achieving higher overall fuel efficiency and lowering carbon emissions. The system involves the installation of an additional electric motor/generator in parallel to the vehicle’s internal combustion engine and is used in conjunction with a DCDC converter and ultracapacitor. The system is used to recapture the energy lost in vehicle braking, significantly reducing a vehicle’s overall energy consumption and lowering vehicle emissions. Experimentally-based evidence is collected and compared for two sample vehicles to deduce the potential fuel and emissions saving. [Copyright &y& Elsevier]

Abstract: This article analyses the energy statistics of 15 European Union countries (EU-15), giving special emphasis to the installed solar photovoltaic and thermal collector capacity. The installed capacities per capita are analysed in relation to the solar radiation income of respective countries with the view to explore the relationship between the solar income and its utilisation as of the year 2006. In terms of the installed solar thermal collector capacity, Austria leads the statistics amongst the countries studied with 223W th collector capacity per capita, followed by Greece with 207W th. Except for Greece, it is observed that the countries with high solar radiation income are lacking to realise their solar potential. Regarding the installed photovoltaic power per capita, Luxembourg leads the pack by a wide margin with 47W p capacity, followed by Germany with 30W p. Fiscal instruments to invigorate the deployment of solar energy have also been identified in this work. [Copyright &y& Elsevier]

Abstract: This paper explores the prospects of using sunshine duration and cloud cover in estimations of daily diffuse irradiation besides the conventional use of global irradiation, where all the parameters are gathered from typical ground-based measurements and proposes optimal region-based models. Data from eight locations across four countries are used for model proposition and subsequent evaluation. Daily sunshine fraction (SF) and daily cloudiness factor (CF) are used along with daily clearness index (K t ) by inter-combination to develop a series of diffuse ratio (K) empirical models for each site. Various statistical tools are employed to establish the criterion of best performing model. Each model’s performance is initially assessed, based on the data it is derived from, and then validated against an independent dataset. This validation is demonstrated by two means: first by testing the models developed for one site against another site in the same region and, secondly by testing the models derived from one section of data against a reserved section from the same site covering a different period of time. The accuracy of prediction is evaluated using three statistical measures (AS, SD, t-statistic). The final assessment also includes calculated versus measured diffuse irradiation plots and indicators such as percent MBD and percent RMSD for potential models. It was found that a model based on K t and SF (and/or CF) performs better than a model based on K t alone within the same data set. However, if these models are tested against the data belonging to a different period of time or a different site, the improvement is less significant. Such model-specificity can be attributed to the fact that the proposed models involve more than one measured parameter, hence greater uncertainty, as against the single-input K t model. Given the climatological variants that differ from site-to-site and measurement uncertainties owing to the poor meteorological standards within the same dataset, validation of such models becomes a challenging task. Nevertheless, it is found that the K t , SF model is an optimum choice when estimating diffuse radiation for independent data, as it yields improved results even over the local K–K t model. Thus, this investigation establishes the improvement in estimation of daily diffuse irradiation that can possibly be achieved through incorporating effective variables along with global radiation for both local as well as independent sites. [Copyright &y& Elsevier]

Abstract: Fossil fuel reserves are diminishing rapidly across the world, intensifying the stress on existing reserves day-by-day due to increased demand. Not only that, fossil fuels, presently contributing to 80% of world primary energy, are inflicting enormous impacts on environment. Climatic changes driven by human activities, in particular the production of greenhouse gas emissions, directly impact the environment. Energy sector has a key role in this regard since energy during its production, distribution and consumption is responsible for producing environmentally harmful substances. A secure and accessible supply of energy is thus very crucial for the sustainability of modern societies. There is an urgent need for a quicker switch over of energy systems from conventional to renewables that are sustainable and can meet the present and projected world energy demand. Solar power is one of the most promising renewables. It is reliable and less vulnerable to changes in seasonal weather patterns. Hydrogen, in the capacity of energy vector, is expected to be the optimum solution for intermittency and storage of energy produced by renewables. Thus, coupled with hydrogen as an energy carrier, solar energy has a large potential to become the fuel of the future. The present study is aimed to explore such potential for India in 2025. India is expected to have a high growth rate in energy demand over the coming years due to its huge population and rapid economic development. By the year 2020, the country''s demand for commercial energy is expected to increase by a factor of 2.5. Presently, more than 90% of the energy demand is met by fossil fuels, in spite of the fact that India has limited fossil fuel resources as compared to global reserves. By the year 2020, India, presently the world''s sixth largest energy consumer, is expected to meet 75% of its oil and gas needs by imports. Being an energy deficient country, it has not been able to keep up with demand, leading to power shortages and supply interruptions. The growing gap between the demand and supply of energy, and environmental externalities associated with fossil fuel require immediate and substantial increases in electric power generation and transmission capacities, and exploitation of new avenues of energy supply that are more stable and environment friendly. The geographic location of India makes it a strong candidate for harnessing solar energy. Thus, solar PV is a potential technology to meet India''s future energy demand and its associated environmental challenges. The present work proposes solar hydrogen based energy network to meet the future energy demand for the major cities of India in a sustainable way. In the proposed energy network, solar PV produced electricity is to be utilized to meet the energy demand during day hours. The solar generated electricity that is excessive of demand is to be stored in the form of hydrogen to be utilized during nocturnal hours and prolonged overcast conditions. A modular approach has been adopted for the purposed energy network to meet the year 2025 demand of six major cities of India: Chennai, Delhi, Jodhpur, Kolkata, Mumbai and Trivandrum. Present as well as projected cost scenarios for 2025 have been provided for all the proposed technologies to evaluate the economical viability of the energy network under study. Based on the futuristic trends, it is foreseen that by the year 2025, the PV electricity would be more economical than the fossil fuel electricity. [Copyright &y& Elsevier]

Light pipes (such as tubular lighting) are simple structures that allow the transmission of daylight from outside to inside a room. They are an increasingly popular product, with CIBSE Building Journal (September 2003) stating that there are now an estimated three million pipes installed throughout the globe. They generally consist of a top collector (often just a polycarbonate hemispheric dome), the pipe itself, and an emitter. Light pipes have different designs and are constantly being improved and updated. Much of the work discussed here considers pipes of reflective aluminium sheets (96% reflectance) that transmits light through multiple specular reflection, but more reflective films are now available that produce even better performances. For example, a film developed by 3M has a reflectance of 98–99%, with the light transmitted via total internal reflection. Such innovations make the light-pipe increasingly efficient, but it is important to quantify this effectiveness by producing reliable predictive methods. The following article, as part of the CIE international technical committee TC3-38 contribution, provides a review of such models/methods and their applications. [Copyright &y& Elsevier]

Much research has been conducted looking at the advantages of using natural daylight for illumination of both domestic and commercial buildings. As an alternative to electric lighting, natural daylight, when exploited to its maximum potential, can be beneficial both economically and environmentally. There are many different applications that have been put forward as a way to maximise natural daylight—one of the most simple is the light-pipe. To investigate the effectiveness of light-pipes, a model is proposed that will predict the light levels resulting from a pipe of given dimensions. This report describes the method of predicting the luminous flux of light-pipes and also proposes methods of calculating, for overcast skies, the illuminance resulting from a given luminous flux.All data used has been obtained from measurements in the UK throughout the year for various locations. The data is therefore the result of actual sky conditions. [Copyright &y& Elsevier]

Provides information on a study on two models used to compute solar irradiance, namely the meteorological radiation model (MRM) and the cloud-cover radiation model (CRM). Overview on the models; Comparison between MRM and CRM; Conclusions.

This article investigates the feasibility of achieving higher performance from ground-source heat-pumps (GSHP) in space heating mode through the use of solar thermal collectors. A novel simulation tool for solar-assisted ground-source heat-pumps (SGSHP) is presented with an analysis of the influence of solar collectors on the improvement of heat pump performance. Solar radiation and climate temperature data of 19 European cities were used to perform simulations of SGSHP and GSHP systems considering a typical residential house. Overall performance coefficients (COP sys ) varied from northern to southern locations between 4.4 and 5.8 for SGSHP and between 4.3 and 5.1 for GSHP. Results show that solar collectors coupling has more impact on performance improvement in regions that benefit from higher irradiance. However, greater running cost savings are achieved in milder climate conditions. Both heat-pump systems are able to effectively contribute to carbon footprint reductions for residential buildings, especially in countries where fossil fuels are the primary source of electricity generation. SGSHP payback periods are found between 8.5 and 23 years from northern to southern localities, making such heating system an economic heating option. SGSHPs are best suited for high irradiance and cool climate locations such as the mountainous regions in southern Europe. [ABSTRACT FROM AUTHOR]

Abstract: There are now several ways of predicting the illuminance produced for different configurations of light pipe. This study is an overview of two such methods for two slightly different forms of light pipe diffuser. Both models are partly empirical in nature but have been formulated using significantly different techniques. Their outputs are also different in presentation, although both models deal with illuminance predictions (with one of the models offering luminous flux predictions also). The models have also used separately obtained measurements in their formulation and so can be seen as being two independent methods, using similar logic, to achieve similar goals. While the two sets of predictions cannot be compared to each other directly (due to the difference in diffuser in each case), the two models can be presented as an indication as to how modelling procedures of this type can be approached. [Copyright &y& Elsevier]