Anthony Vassallo

A Compact, Highly Efficient and Flexible Polymer Ultra-Wideband Antenna

A compact, highly efficient and flexible ultra-wideband antenna operating from 3 to 20 GHz is proposed in this letter. The antenna is completely made from polymer comprising a patterned conductive polymer (PEDOT) thin film attached to a transparent sticky tape substrate. The overall dimension is less than a quarter-wavelength at the lowest frequency of operation and the device reaches a radiation efficiency of over 85% averaged throughout the frequency band. The antenna performs well under various bending conditions as demonstrated by measurements. The realized antenna offers great mechanical flexibility and robustness which indicates its promising potential for possible seamless integration in flexible electronics.

The influence of ionic liquid additives on zinc half-cell electrochemical performance in zinc/bromine flow batteries

Six ionic liquids were assessed for their suitability as alternative bromine-sequestering agents (BSAs) in zinc/bromine redox flow batteries (Zn/Br RFBs) via comparison against conventional BSA, 1-ethyl-1-methylpyrrolidinium bromide ([C2MPyrr]Br). These alternative BSAs included the bromide salts of the following cations: 1-ethyl-1-methylpiperidinium ([C2MPip]+), 1-ethyl-1-methylimidazolium ([C2MIm]+), 1-(2-hydroxyethyl)-3-methylimidazolium ([C2OHMIm]+), 1-ethylpyridinium ([C2Py]+) and 1-(2-hydroxyethyl)pyridinium ([C2OHPy]+). Cyclic and linear sweep voltammetry, as well as electrochemical impedance spectroscopy, were performed to understand the influence of electrolytes containing these ionic liquids on zinc half-cell electrochemical performance. Solutions with [C2Py]Br, [C2MIm]Br and [C2OHPy]Br improved zinc half-cell performance (highest-magnitude current, charge, maximum power and energy) when compared to those utilizing [C2MPyrr]Br. Electrolytes employing these BSAs also reduced the nucleation overpotential of zinc electrodeposition and stripping compared to those using [C2MPyrr]Br. Zinc electrodeposits obtained during charging from electrolytes containing the different BSAs were analyzed via scanning electron microscopy and X-ray diffraction. Scanning electron micrographs showed a strong relationship between the chemical structure of the BSA employed and the crystallinity of zinc electrodeposits, with solutions containing [C2OHMIm]Br, [C2Py]Br and [C2OHPy]Br producing more compact zinc deposits than those with other BSAs. These findings warrant further investigation of BSAs with delocalized cationic charge. While these compounds have been proposed for application in Zn/Br systems, they are also potentially adaptable to other types of RFBs, which employ the Br2/Br− redox couple and use electrolytes containing BSAs.

The influence of novel bromine sequestration agents on zinc/bromine flow battery performance

This study benchmarks cycle performance of electrolyte solutions containing novel bromine sequestration agents (BSA) in a zinc bromine flow battery. Five alternative BSA candidates – 1-ethyl-1-methylpiperidinium bromide ([C2MPip]Br), 1-ethylpyridinium bromide ([C2Py]Br), 1-(2-hydroxyethyl)-pyridinium bromide ([C2OHPy]Br), 1-ethyl-3-methylimidazolium bromide ([C2MIm]Br) and 1-(2-hydroxyethyl)-3-methylimidazolium bromide ([C2OHMIm]Br) were investigated under operational conditions typical for zinc bromine flow batteries. Results were compared to the conventional BSA, 1-ethyl-1-methylpyrrolidinium bromide ([C2MPyrr]Br). Electrolytes containing the various alternative BSAs were tested at bench scale in a full-cell battery setup under controlled electrolyte flow and temperature. The evaluated performance parameters were: voltaic efficiency, coulombic efficiency, energy efficiency and recoverable charge. A correlation between BSA–bromine bond strength and cycle performance was observed. Performance of the tested electrolytes varied widely, and gains in coulombic efficiency were generally offset by losses in voltaic efficiency. [C2Py]Br and [C2MIm]Br produced cycle performance improvements compared to the other BSAs studied.

Wind effects in solar fields with various collector designs

Parabolic trough power plants are often located in areas that are subjected to high wind speeds, as an open terrain without any obstructions is beneficial for the plant performance. The wind impacts both the structural requirements and the performance of the plant. The aerodynamic loads from the wind impose strong requirements on the support structure of the reflectors, and they also impact the tracking accuracy. On a thermal level the airflow around the glass envelope of the receiver tube cools its outer surface through forced convection, thereby contributing to the heat loss.Based on previous studies at the level of an individual row of collectors, this study analyses the wind effects in a full-scale solar field of different continuous and staggered trough designs. The airflow around several rows of parabolic trough collectors (PTC) is simulated at full scale in steady state simulations in an atmospheric boundary layer flow using the commercial computational fluid dynamics software ANSYSO® CFX 15.0. The...

The Impact of auctions on residential sale prices : Australian evidence

This study re-examines the variation in selling prices between the auction and private treaty method of sales. Using sales data from five major Australian capital cities over a four year period, we estimate a hedonic pricing model. Results indicate that for house sales, auctions lead to greater selling prices across all cities examined. However, results for unit sales reveals that this auction premium is only evident in two cities where auctions are less prevalent. Further analysis reveals that self-selection (where a particular method of sale is selected to maximise the selling price) is evident across the sample. After controlling for this self-selection bias using a two-stage model, houses sold via auction generally command a higher price. This suggests that the auction method of selling provides a price premium over the private treaty method of sale.

Zinc Electrodeposition Morphology

The electrochemical performance of the zinc half-cell is strongly linked to the quality and morphology of zinc electrodeposits generated during the charging phase. The structure of the zinc plating also dictates performance characteristics such as efficiencies, charge densities and peak current values during the subsequent discharge phase. The previous chapter described and analyzed the considerations arising from chemical reactions occurring at the zinc-side electrode. Following from that point, this chapter describes the underlying reasons why different zinc plating morphologies are obtained under different conditions and how certain behavior such as dendritic growth can be detrimental to Zn/Br performance. Promising methods for solving such issues are then identified from a wide range of literature including studies directly related to redox flow batteries as well as from the highly established electroplating industry. The primary means of controlling zinc crystal structure involves the use of organic additives to achieve a specific growth template and rate. Additionally, the merits and drawbacks of alternative strategies such as controlling deposition rates are investigated in this chapter.

Electricity Storage: Renewable Energy Applications in the Australian Context

Exploiting renewable energy sources makes sense on many levels: first as a response to the world?s reliance on fossil fuels and to reduce climate-changing emissions. But beyond that, more mature renewable generation technologies deployed in areas naturally blessed with abundant renewable resources are beginning to challenge traditional fuels for cost-effectiveness, even as subsidies for low-carbon generation are wound back.

PV-Battery Nanogrid Systems

With the rapid reduction in PV system prices in recent years, interest in the use of grid-connected PV generation and/or battery systems has notably increased. The previous chapter presented a methodology for concurrent optimal selection, sizing, and operation scheduling of grid-connected or off-grid DGS systems. Here, we focus on PV and battery sources as special DGS systems and study a few cases to investigate the performance of such systems in various conditions.

Sensitivity Analysis of Grid-Connected PV-Battery Systems

We investigate the impact of various techno-economic parameters such as PV/battery installation costs, electricity tariff, feed-in tariff, geographic location, and load profile on the feasibility of grid-connected PV-Battery systems.

The “Death Spiral” for the Utility Industry: A Myth or Reality?

The recent rapid decline in PV prices has brought grid parity, or near grid parity for PV in many countries. This has prompted public and academic interest in “grid defection”, “leaving the grid” or “living off-grid.” Grid defection has been described as a “death spiral” for transmission and distribution companies. Here, we review the arguments about the reality of the death spiral.