Intelligent Multi-Vehicle DC/DC Charging Station Powered by a Trolley Bus Catenary Grid

This article deals with the major challenge of electric vehicle charging infrastructure in urban areas—installing as many fast charging stations as necessary and using them as efficiently as possible, while considering grid level power limitations. A smart fast charging station with four vehicle access points and an intelligent load management algorithm based on the combined charging system interface is presented. The shortcomings of present implementations of the combined charging system communication protocol are identified and discussed. Practical experiments and simulations of different charging scenarios validate the concept and show that the concept can increase the utilization time and the supplied energy by a factor of 2.4 compared to typical charging station installations.

QRB−tree Indexing: Optimized Spatial Index Expanding upon the QR−tree Index

Support for region queries is crucial in geographic information systems, which process exact queries through spatial indexing to filter features and subsequently refine the selection. Although the filtering step has been extensively studied, the refinement step has received little attention. This research builds upon the QR−tree index, which decomposes space into hierarchical grids, registers features to the grids, and builds an R−tree for each grid, to develop a new QRB−tree index with two levels of optimization. In the first level, a bucket is introduced in every grid in the QR−tree index to accelerate the loading and search steps of a query region for the grids within the query region. In the second level, the number of candidate features to be eliminated is reduced by limiting the features to those registered to the grids covering the corners of the query region. Subsequently, an approach for determining the maximal grid level, which significantly affects the performance of the QR−tree index, is proposed. Direct comparisons of time costs with the QR−tree index and geohash index show that the QRB−tree index outperforms the other two approaches for rough queries in large query regions and exact queries in all cases.

UAV-BASED LIDAR HIGH-RESOLUTION SNOW DEPTH MAPPING IN THE SWISS ALPS: COMPARING FLAT AND STEEP FORESTS

Snow depth mapping in Alpine forests is of high importance for hydrogeology, ecology, tourism, and natural hazards prevention. Different remote sensing approaches have been employed for the precise mapping of snow depth within forests. However, optical sensors cannot provide below-canopy information. While Airborne Laser Scanning (ALS) systems have been used successfully in this context and allow obtaining data below canopies, the costs of acquisitions are very high, not allowing frequent data acquisitions. UAV-based Lidar technology potentially can provide the critical below-canopy information at lower cost and allows for frequent acquisitions.First attempts to employ a UAV-based Lidar system in forests have proven promising, but they are limited to flat forests and to grid-level snow depth calculations. In this study, we present UAV-based Lidar data of both flat and steep forests. Different Lidar processing workflows are analyzed and compared, and snow depth algorithms are used both at the point and the grid level. Whereas the UAV-Lidar system proved capable of mapping snow in both environments, the steep forests' data processing comes with greater challenges, especially for the 3D registration, ground classification, and point-to-point snow depth calculations.

Recent Progress in Cathode Materials for Sodium-Metal Halide Batteries

Transitioning from fossil fuels to renewable energy sources is a critical goal to address greenhouse gas emissions and climate change. Major improvements have made wind and solar power increasingly cost-competitive with fossil fuels. However, the inherent intermittency of renewable power sources motivates pairing these resources with energy storage. Electrochemical energy storage in batteries is widely used in many fields and increasingly for grid-level storage, but current battery technologies still fall short of performance, safety, and cost. This review focuses on sodium metal halide (Na-MH) batteries, such as the well-known Na-NiCl2 battery, as a promising solution to safe and economical grid-level energy storage. Important features of conventional Na-MH batteries are discussed, and recent literature on the development of intermediate-temperature, low-cost cathodes for Na-MH batteries is highlighted. By employing lower cost metal halides (e.g., FeCl2, and ZnCl2, etc.) in the cathode and operating at lower temperatures (e.g., 190 °C vs. 280 °C), new Na-MH batteries have the potential to offer comparable performance at much lower overall costs, providing an exciting alternative technology to enable widespread adoption of renewables-plus-storage for the grid.

Integrated Planning Framework For Pumped Hydro Energy Storage (PHES) Systems

The electric power industry worldwide has been focusing towards increasing utilization of renewable energy resources such as wind and solar to build and maintain clean, reliable and affordable electricity systems. Although these resources are environmentally clean, their uncertain and intermittent nature is a significant issue. Similarly, other energy generators such as nuclear and gas have serious environmental issues. These issues can be resolved with effective management of supply and demand using appropriate energy storage. Although various energy storage options are available, PHES is globally proven technology at grid level. Additionally, gravity power module (GPM) is a newly emerged technology in the power industry. However, its applications at full scale are still awaited. This research developed methodologies for integrated planning framework for PHES systems at grid level, employing a GIS-based model to identify feasible PHES sites, optimizing the scheduling of feasible PHES potential, and performing the financial analysis of PHES system. The methodologies were applied on grid-connected electricity area of Ontario that identified 285 feasible PHES and GPM sites with storage potential of 56,268 MWh. This research proposed the formation of a cooperative association namely „Pumped Hydro Storage Association (PHSA)‟ for integration of PHES system in the electricity market system operated by the IESO in Ontario. Using 2016 data, the optimization model resulted that PHSA supplied real-time energy 28,134 MWh/ day, provided ancillary services including variable operating reserve 23,914 MWh/ day, fixed operating reserve 4,220 MWh/ day, and purchased energy 65,060 MWh/ day. The optimization results and resultant financial indicators confirmed that proposed PHES system is technically and financially viable in a large electricity market system. As an initial step, partial development of PHES and GPM plants was proposed with an initial capital cost of C$ 1,052 Million utilizing 7,767 MWh/ day energy potential that resulted in a net profit share of C$ 13.36/ MWh for each participatory plant. Finally, the developed PHES planning framework for PHES system can certainly be found valuable to the policymakers, system operators, energy developers, research scholars, engineers, financial analysts and scientist community to work on future improvement in the PHES system.