Exploring the feasibility of electric vehicle travel for remote communities in Australia

Remote communities in Australia face unique mobility challenges that stand to be further complicated by the transition from Internal Combustion Engine (ICE) vehicles to Electric Vehicles (EVs). EVs offer a range of advantages that include lower maintenance requirements and independence from costly, dangerous and polluting petroleum imports that have long been burdensome for remote communities. Yet the adoption of electric vehicles in Australia has been slow by international standards, and what policy strategies do exist tend to focus on incentivizing uptake among urban residents with the means to afford new technologies, potentially leaving remote communities in the 'too hard basket'. In this study we assess the feasibility of EVs for a sample of communities in remote Australia using Geographic Information System analysis of travel distances between communities and service hub towns utilizing present-day EV specifications and charging technologies. We show that while EV travel is often not currently feasible for trips to large service hub towns using low-range vehicles, over 99% of communities and residents considered would be able to travel to their nearest small service hub town with existing long-range EVs. This finding suggests that while the barriers to the electrification of transport in remote communities are significant, they are not insurmountable and are deserving of consideration in national and state policy developments in the deployment of charging infrastructure

Absorption enhancing proximity effects in aperiodic nanowire arrays

Aperiodic Nanowire (NW) arrays have higher absorption than equivalent periodic arrays, making them of interest for photovoltaic applications. An inevitable property of aperiodic arrays is the clustering of some NWs into closer proximity than in the equivalent periodic array. We focus on the modes of such clusters and show that the reduced symmetry associated with cluster formation allows external coupling into modes which are dark in periodic arrays, thus increasing absorption. To exploit such modes fully, arrays must include tightly clustered NWs that are unlikely to arise from fabrication variations but must be created intentionally.Comment: Accepted by Optics Expres

Optimizing Photovoltaic Charge Generation of Nanowire Arrays: A Simple Semi-Analytic Approach

Nanowire arrays exhibit efficient light coupling and strong light trapping, making them well suited to solar cell applications. The processes that contribute to their absorption are interrelated and highly dispersive, so the only current method of optimizing the absorption is by intensive numerical calculations. We present an efficient alternative which depends solely on the wavelength-dependent refractive indices of the constituent materials. We choose each array parameter such that the number of modes propagating away from the absorber is minimized while the number of resonant modes within the absorber is maximized. From this we develop a semi-analytic method that quantitatively identifies the small range of parameters where arrays achieve maximum short circuit currents. This provides a fast route to optimizing NW array cell efficiencies by greatly reducing the geometries to study with full device models. Our approach is general and applies to a variety of materials and to a large range of array thicknesses.Comment: Accepted by ACS Photonic

Fano resonances of dielectric gratings : symmetries and broadband filtering

The guided mode resonances (GMRs) of diffraction gratings surrounded by low index materials can be designed to produce broadband regions of near perfect reflection and near perfect transmission. These have many applications, including in optical isolators, in hybrid lasers cavities and in photovoltaics. The excitation of rapid GMRs occurs in a background of slowly varying Fabry-Perot oscillation, which produces Fano resonances.We demonstrate the critical role of the polarity of adjacent Fano resonances in the formation of the broadband features. We design gratings for photovoltaic applications that operate at wavelengths where material absorption must be considered and where light is incident at non-normal angles.15 page(s

Guided modes of a wire medium slab : comparison of effective medium approaches with exact calculations

Erratum to article published in Physical review B 93, 159903(E) (2016), doi: https://doi.org/10.1103/PhysRevB.93.159903 We derive the dispersion relations of the guided modes in wire media slabs using a transmission and reflection matrix approach, providing a physically insightful perspective into wave propagation in wire media slabs. We find new approximations to the dispersion relations, and assess their accuracy and the regimes for which they hold. We do so both analytically, and against exact calculations of the electromagnetic fields without reference to effective media. We then analyze the effects of the background refractive index on the guided modes, proposing explanations for the observed behavior.10 page(s

Perfect absorption in ultra-thin uniform and nanostructured media

We show that perfect absorption can be achieved in ultra-thin gratings composed of weakly absorbing dielectric materials combined with a mirror. The structures can be fabricated using standard processing techniques.2 page(s

Perfect absorption in uniform and nanostructured media

We consider the conditions for perfect absorption in uniform thin-films and in thin gratings. We find that perfect absorption of TE polarized light can occur in gratings composed of weakly absorbing materials.2 page(s

Simulations of silicon nanowire arrays for photovoltaics - more absorption with less silicon

Using a novel numerical method we calculate the energy absorption of a silicon nanowire array, for photovoltaics. We show that dilute arrays deliver optimal integrated absorption on a per-silicon-volume basis, and identify the enhancement mechanism.2 page(s