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Building-Integrated Concentrated Photovoltaics (BICPV) is based on Photovoltaic (PV) technology which experience a loss in their electrical efficiency with an increase in temperature that may also lead to their permanent degradation over time. With a global PV installed capacity of 303 GW, a nominal 10 °C decrease in their average temperature could theoretically lead to 15 GW increase in electricity production worldwide. Currently, there is a gap in the research knowledge concerning the effectiveness of the available passive thermal regulation techniques for BICPV, both individually and working in tandem. This paper presents a novel combined passive cooling solution for BICPV incorporating micro-fins, Phase Change Material (PCM) and Nanomaterial Enhanced PCM (n-PCM). This work was undertaken with the aim to assess the unreported to date benefits of introducing these solutions into BICPV systems and to quantify their individual as well as combined effectiveness. The thermal performance of an un-finned metallic plate was first compared to a micro-finned plate under naturally convective conditions and then compared with applied PCM and n-PCM. A designed and fabricated, scaled-down thermal system was attached to the electrical heaters to mimic the temperature profile of the BICPV. The results showed that the average temperature in the centre of the system was reduced by 10.7 °C using micro-fins with PCM and 12.5 °C using micro-fins with n-PCM as compared to using the micro-fins only. Similarly, the effect of using PCM and n-PCM with the un-finned surface demonstrated a temperature reduction of 9.6 °C and 11.2 °C respectively as compared to the case of natural convection. Further, the innovative 3-D printed PCM containment, with no joined or screwed parts, showed significant improvements in leakage control. The important thermophysical properties of the PCM and the n-PCM were analysed and compared using a Differential Scanning Calorimeter. This research can contribute to bridging the existing gaps in research and development of thermal regulation of BICPV and it is envisaged that the realised incremental improvement can be a potential solution to (a) their performance improvement and (b) longer life, thereby contributing to the environmental benefits.

Abstract Fuel cell vehicles and carsharing depict two potential solutions with regard to pollution and noise from traffic in cities. They are most effective when combined, and hydrogen is produced via electrolysis using renewables. One major hurdle in utilizing fuel cell vehicles is to size hydrogen refueling stations (HRS) and hydrogen production via electrolysis properly in order to fulfill the carsharing vehicles’ demand at any given time. This paper presents data on refueling behavior in free-floating carsharing, which have not been available thus far. Refueling profiles of hydrogen carsharing vehicles are modeled based on this data. Furthermore, this analysis presents and applies a methodology for optimizing topology of a wind turbine-connected HRS with onsite electrolysis via an evolutionary algorithm. This optimization is conducted for different carsharing fleet sizes, and HRS profitability is evaluated. The results show that larger fleets are capable of decreasing hydrogen production costs significantly. Moreover, adding capacity to the HRS in order to prepare for hydrogen demand from private vehicles in the future does not significantly increase costs. However, overall costs are still high compared to the current market price in Germany, requiring further cost reductions.

Abstract Ocean thermal energy is formed by temperature difference between sea surface and deep sea. Underwater glider is a new kind of autonomous underwater vehicle. It ascends and descends between the sea surface and deep sea periodically by adjusting its net buoyancy. Thermal underwater glider can harvest ocean thermal energy through the utilization of phase change material (PCM) and convert it into mechanical energy for buoyancy-driven. In this paper, the fundamental principle of this thermal engine is unveiled. A nonlinear model for relationship between system pressure and phase change rate is established. Based on the established nonlinear model, influencing factors for system pressure and stored energy are analyzed comprehensively. Selected PCM is Hexadecane. Value range for air solubility in liquidus PCM is 0.06–0.1, and for residual air in the system is −0.02 to 0.05. The influence of these two factors on relative energy storage is similar. For typical values of air solubility 0.08 and residual air 0.005, utilization ratio of the thermal engine is less than 50%. Through experiment in the lake, the nonlinear model was verified, maximum system pressure was 12.5 MPa, and average stored energy of each cycle was 2.48 kJ. A prototype of thermal underwater glider has also been tested in the South China Sea. It had worked continuously for 29 days without any failure. Total number of working profile was 121 and total cruising range was 677 km, total stored energy was 300 kJ. High reliability and performance was validated by the sea trial.

Biomass gasification is considered a key technology in reaching targets for renewable energy and CO2 emissions reduction. This study evaluates policy instruments affecting the profitability of biom ...

Abstract This paper describes an analysis approach to assess water consumption attributed to electricity generation required to meet the demand for the entire Saudi residential building stock. In addition, the analysis aims at estimating the water consumption reduction due to cost-effective energy retrofit measures for the Saudi housing stock. The analysis estimated that the water consumed annually to generate electricity for the Saudi entire housing stock is 135 MCM representing almost 10% and 4% of the water used by the industrial sector. Moreover, it is found that both electricity generation need and associated water consumption can be reduced by 15.7% when lighting is retrofitted with low-energy fixtures and by 25.8% when high efficiency air conditioning systems are installed for all the existing Saudi housing stocks. For the housing stock located in the Central region with prevalent dry climates, replacing existing air conditioning by evaporative coolers can save 11.1 TWh/a (25.5%) in electricity consumption but increase the water consumption by 36.2 MCM/a (80.6%). A cost-benefit analysis of lighting retrofit is found to be highly cost-effective for both households and the government with payback periods of less than 1 year.

Parabolic reflectors, also known as parabolic troughs, are widely used in solar thermal power plants. This kind of power plants is usually located on desert climates, where the combined action of wind and dust can be of paramount importance. In some cases it becomes necessary to protect these devices from the joined wind and sand action, which is normally accomplished through solid windbreaks. In this paper the results of a wind tunnel test campaign, of a scale parabolic trough row having different windward windbreaks, are reported. The windbreaks herein considered consist of a solid wall with an upper porous fence. Different geometrical configurations, varying the solid wall height and the separation between the parabolic trough row and the windbreak have been considered. From the measured time series, both the mean and peak values of the aerodynamic loads were determined. As it would be expected, mean aerodynamic drag, as well as peak values, decrease as the distance between the windbreak and the parabolic increases, and after a threshold value, such drag loads increase with the distance.

Abstract One of the strategies to improve environmentally friendly energy harvesting can be realized by using biomass as a primary energy source for generating electricity and H2. In addition, high energy efficiency can be achieved by minimizing exergy loss through process integration and exergy recovery. As an implementation, this study proposes a cogeneration system for black liquor (BL) to co-produce electricity and H2. The system primarily comprises BL drying, circulating fluidized bed gasification, syngas chemical looping (SCL), and power generation. The Aspen Plus V8.8 software package is used for modeling and performing calculations of the proposed integrated system. Furthermore, thermodynamic analysis of gasification is performed by employing Gibbs energy minimization. The effects of target solid content on the required total work and compressor outlet pressure during drying and gasification with different steam-to-fuel ratios are evaluated. Moreover, the SCL process adopts three reactors, namely, the reducer, oxidizer, and combustor. Compared to conventional processes, the integrated drying-gasification-SCL processes are significantly cleaner and more energy efficient. The proposed integrated system can achieve a net energy efficiency of about 70% with almost 100% carbon capture.

Abstract Fossil fuel run diesel engines are being favored in light, medium and heavy duty applications as they exhibit higher fuel conversion efficiencies. Direct injection diesels are still facing challenges to obtain trade-off between oxides of nitrogen and particulate emissions. There are sophisticated strategies such as common rail direct injection, particulate filters with associated sensors and actuators but limited to expensive comfort vehicles. In the present experimental study, a mechanically operated simple component, variable timing fuel injection cam, is designed for a 510 cc automotive type naturally aspirated, water-cooled, direct injection diesel engine. Modifications in the fuel injection cam and gear train are carried out to suit the existing engine configuration. Variable speed tests are carried out for testing the efficacy of component on both engine and chassis dynamometers for performance and emissions. It is observed that the engine which is already retarded could further be retarded with variable timing fuel injection cam. Significant reductions in NO x and smoke emission levels are achieved. Combined effect of VIC with 7% EGR could reduce CO by about 88%, HC + NO x by 37% and PM emissions by 90%. The Engine incorporated with the designed component and EGR, successfully satisfied the existing emission norms with improved power and specific fuel consumption.