ALBERT

Description: Earth-abundant kesterite Cu 2 ZnSnSe 4 material is a promising candidate for the mass production of low-cost thin film solar cells. However, the synthesis of single-phase kesterite films is especially challenging, since the kesterite single-phase region in the equilibrium phase diagram is very narrow. In this study, the metal composition was varied within the Cu-poor composition range in order to study the presence of Sn-Se secondary phases. Both SnSe and SnSe 2 are found in copper-poor CZTSe absorbers where Zn/Sn   1 because the studied composition range is actually copper-poor zinc-rich and tin-rich. The Sn-Se secondary phases can be detected using X-ray diffraction, a bulk detection method. They are also detected at the absorber's surface by SEM and Raman spectroscopy. Therefore, when the Sn-Se phases are present, at least a part of them is located at the absorber's surface, which is highly detrimental to device performance. Acting as shunting paths, they reduce the device power conversion efficiency and demonstrate an apparent quantum efficiency effect under reverse bias. Removal of these phases from the surface by chemical etching greatly reduces their detrimental influence.

Description: In July 2014, the Port of Los Angeles (POLA) and the Shanghai Municipal Transportation Commission (SMTC, formerly Port of Shanghai) entered into an EcoPartnership focused on reducing air emissions at both ports by instituting and expanding the use of Shore Power on ocean-going vessels while at berth. In 2004, POLA became the first port in the world to have a container ship plug into shore power through their Alternative Maritime Power™ (AMP™) program. Since then, the shore power plug-in program has expanded to include all container terminals and the cruise terminal at POLA, and significant air emission reductions have occurred as a direct result of those efforts. The EcoPartnership builds upon that experience to support the development of SMTC's capabilities in technology, strategy, and policy development as it relates to shore power. POLA and SMTC developed annual milestones extending through the term of the EcoPartnership agreement with a goal of successfully setting up and implementing a Shore Power program at a Shanghai terminal, including the successful operation of four shore power-ready terminals by 2017. Through their term in the EcoPartnership program, both ports will continue to collaborate and learn from each other on a variety of environmental issues. The potential benefits of the EcoPartnership extend much further. It is envisioned that coordinated development of compatible shore power infrastructure will encourage ship owners to more rapidly convert their fleet to allow ships to plug in, expediting emission reductions at both ports. Additionally, this project will serve as an example that other ports across the globe can use to implement shore power programs at their facilities.

Description: There are numerous sources of mechanical energy in our environment, such as ultrasonic waves, body movement, and irregular air flow/vibration. Here, we present a simple, cost-effective approach for fabricating a flexible nanogenerator and apply it to harvest energy from environmental mechanical vibrations. The nanogenerator was based on ZnO nanorods grown on common paper substrate using a low-temperature hydrothermal method. Piezoelectric currents were measured by attaching the nanogenerator on the surface of a cantilever and a wind-up drum, respectively. At the same time, the vibrations of the cantilever and wind-up drum could also be characterized by the corresponding output signals. This is a practical and versatile technology with the potential for converting a variety of environment energy into electric energy, and also with the application for pre-warning of emergency, such as earthquake and burgling.

Description: A new simulation tool aimed at characterizing the thermal behavior of parabolic trough collectors over a wide range of pressures and gas mixtures in the vacuum chamber is presented in this study. The model is able to accurately predict overall efficiency and heat losses obtained in a number of experimental sources based on both on-sun and off-sun testing, with vacuum in the annulus and no hydrogen. Excellent agreement of the simulations with experiments including different gas compositions, especially with high hydrogen concentrations, is achieved through the use of molecular dynamics results for the determination of the accommodation coefficient of the mixture. Additional experiments were carried out to validate the accuracy of the model over a range of pressures between 10 −4 and 130 mbar. The accurate modelling of rarefied gas dynamics presented here also leads to an excellent agreement between simulations and experiments over the whole pressure range. An accurate determination of the performance in such extreme conditions is critical for an adequate Operation & Maintenance strategy, as well as the development of effective predictive and preventives plans.

Description: This study provides an economic and energy analysis of the implementation of geothermal systems to meet the needs of a typical 130 m 2 dwelling of a Canadian individual. The objective is to determine the monetary balance after 22 years, the net present value, the internal return rate, and annual savings for the same system operating under different climatic conditions and in different provinces (legislations, costs of fuel) to determine whether or not an individual should implement such a system in 2014. The geothermal system is used for both space heating and cooling, and to provide for 25% of the total amount of domestic hot water. The simulations are performed with RETScreen ® for four Canadian cities: Halifax, Montreal, Toronto, and Vancouver. For the investigated configurations, it appeared that the cost of energy and its sources, which varied greatly according to the location, are the factors that most strongly influenced the economic viability of the proposed geothermal system, while climate was only a secondary impact. The impact of carbon taxes and equivalent monetary subsidies does not significantly modify the economic outcomes for Halifax and Montreal. However, for Toronto and Vancouver, these would need to reach between 280 and 300 Can$/tCO 2 eq to attain economic balance.

Description: The actuator disc (AD) model is commonly used to simplify the simulation of horizontal-axis wind-turbine aerodynamics. The limitations of this approach in reproducing the wake losses in wind farm simulations have been proven by a previous research. The present study is aimed at providing an experimental analysis of the near-wake turbulent flow of a wind turbine (WT) and a porous disc, emulating the actuator disc numerical model. The general purpose is to highlight the similarities and to quantify the differences of the two models in the near-wake region, characterised by the largest discrepancies. The velocity fields in the wake of a wind turbine model and a porous disc (emulation of the actuator disc numerical model) have been measured in a wind tunnel using stereo particle image velocimetry. The study has been conducted at low turbulence intensity in order to separate the problems of the flow mixing caused by the external turbulence and the one caused by the turbulence induced directly by the AD or the WT presence. The analysis, as such, showed the intrinsic differences and similarities between the flows in the two wakes, solely due to the wake-induced flow, with no influence of external flow fluctuations. The data analysis provided the time-average three-component velocity and turbulence intensity fields, pressure fields, rotor and disc loading, vorticity fields, stagnation enthalpy distribution, and mean-flow kinetic-energy fluxes in the shear layer at the border of the wake. The properties have been compared in the wakes of the two models. Even in the absence of turbulence, the results show a good match in the thrust and energy coefficient, velocity, pressure, and enthalpy fields between wind turbine and actuator disc. However, the results show a different turbulence intensity and turbulent mixing. The results suggest the possibility to extend the use of the actuator disc model in numerical simulation until the very near wake, provided that the turbulent mixing is correctly represented.

Description: High-frequency (50 Hz) observational data from the 200-m tower data (Reese Technology Center, Texas) have been prescribed as inflow conditions into the NREL FAST code in order to evaluate the structural impacts of Low Level Jets (LLJs) on a typical commercial wind turbine. A vertical region of interest for the analysis of interaction LLJ–wind turbine has been delimited, and the LLJ length scales have been calculated. The analysis of power spectra exhibited a deviation within the inertial subrange from the classical −5/3 slope in a log-log representation towards a lower slope, which indicated a lower rate of energy transfer when the LLJ was present. It has been observed that during a LLJ event the turbulence intensity and turbulence kinetic energy were significantly lower than those during unstable conditions; and cyclical aerodynamic loads on the turbine blades produced a negative impact on the wind turbine, mainly due to the enhanced wind shear. Dominant frequencies present in the power spectra of the incoming wind were also observed in frequencies related to the dynamic loads of the turbines. It was found that the wind turbine can mimic the signals from the approaching inlet flow, although some of the replication can be altered or annulled in a wind farm.

Description: A basic catalyst made of charred shrimp shells treated with potassium fluoride (KF) was employed in the transesterification reaction of soybean oil in the presence of methanol to produce methyl esters. The shells used here are wastes from freshwater shrimp farming in the western region of the state of Paraná, Brazil, which are normally discarded in dumps/landfills and are a rich source of the biopolymer chitin (poly-β-1,4-N-acetyl-D-glucosamine). Charring of the shells (at 450 °C for 2 h) is aimed at partially eliminating rests of proteins and fibers, as well as acetyl groups (-CH 3 CO), carbon dioxide (-CO 2 ) and water, causing the rearrangement of the chitin structure. The subsequent treatment of the shells with KF (impregnation and activation at 250 °C for 2 h) potentiated the basic sites on the catalyst surface, rendering it active in the transesterification reaction. The catalysts and shrimp shells were characterized by thermal gravimetric analysis, differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, N 2 physisorption (Braunauer, Emmet and Teller) (BET), and Hammett basicity. An experimental design was created to evaluate the effect of the following variables of the transesterification reaction:temperature, catalyst weight ratio, and molar ratio of oil:alcohol. The results indicate that the treatment with KF increased the basicity of the catalyst. The highest conversion into methyl esters obtained with the experimental design was 86.3%, using an oil:alcohol molar ratio of 1:9, 3.0% (w/w) of catalyst, 85 °C, and 3 h of reaction. Leaching tests indicated that, after 10 h of refluxing in methanol, a conversion rate of 52.4% was achieved using the catalyst leached in optimized conditions. Kinetic studies showed that chemical equilibrium was established after 8 h of reaction, reaching a conversion rate of 96.7%, which reveals the potential of the catalyst to produce methyl esters (biodiesel).

Description: The performance of several Wave Energy Converter devices is evaluated at three sites located on the west side of Sicily. To select the most energetic site, the average potential wave energy along the coasts of Sicily is evaluated by adopting a third-generation spectral wave propagation model using as boundary conditions the European Centre for Medium-Range Weather Forecasts operational archive wave and wind data. The most energetic sites are on the western side of Sicily. In the three hotspots identified, the mean energy flux is within the range of 5.33–7.52 kW/m. The analysis shows that all considered devices have a low capacity factor in their original configurations (2.19%–5.12%). The main causes of the poor results in terms of energy production are related to the fact that such devices are optimized for high-energy waves. A resizing of the devices on the basis of the local wave climate showed that a capacity factor that exceeds 30% could be obtained.