Cadmium Recovery from Spent Ni-Cd Batteries: A Brief Review

The significant increase in the demand for efficient electric energy storage during the past decade has promoted an increase in the production and use of Cd-containing batteries. On the one hand, the amount of toxic Cd-containing used batteries is growing, while on the other hand, Cd is on a list of critical raw materials (for Europe). Both of these factors call for the development of effective technology for Cd recovery from spent batteries. The present paper is aimed at providing a short review of the recent progress in Cd recovery from spent batteries. Statistical data from the past decade on the source of Cd, its global production, and Ni-Cd battery recycling are given in the introduction. A short overview of the pyro-and hydro-metallurgical methods of metal production is provided. Recent progress in Cd recovery by commercial methods during the past decade is reviewed.

Investigation on Using Low Voltage Automatic Regulation to Minimize the Impacts of Charging Plug-in Electric Vehicles in Distribution Systems

The growth of micro and mini distributed generation and, more recently, the use of electric energy storage systems and the incentives for electric mobility are important examples of the transformations that distribution networks have been going through. In this context, this paper firstly presents the impacts of uncoordinated plug-in electric vehicles (PEVs) charging in a real Brazilian distribution system. Four scenarios were elaborated with different PEVs penetration levels and the results show increased voltage unbalance, system losses, and violations of the steady-state voltage limits, even in the presence of an automatic voltage regulator installed in the medium voltage network. Then, as the main contribution, the potential usage of automatic voltage regulation at the low voltage network was investigated to minimize the negative impacts of uncontrolled PEV charging on distribution system steady-state operation. It is important to highlight that this is not a common practice of utilities in Brazil. The obtained results showed that regulating the voltage at the low voltage side could be an effective solution to keep the voltages within statutory limits.

Operating conditions of electric energy storage system in DC traction power supply for single-track sections of railways

Considered are the issues of using electric energy storage system in the traction power supply of direct current of a single-track section. An overview of the main directions of domestic and foreign research in the field of using these systems to increase the capacity and energy efficiency of power supply systems is given. Modeling the operation of energy storage system in traction power supply is based on the calculation of load graphs within the boundaries of inter-substation zones, formed depending on the conditions for the passage of trains and traction load on the railway section. The main provisions of the method for choosing locations and determining the parameters of energy storage system in traction power supply are considered. On the example of one of the inter-substation zones of the Sverdlovsk railway, the influence of the power of the active sectioning station on the increase in the minimum voltage level at the pantograph of the electric rolling stock is shown. The graphs of the degree of charge and the corresponding frequency distributions are given, which make it possible to evaluate the operating conditions of the electric energy storage system depending on the conditions for the formation of the traction load, as well as the graphs of the load of the electric energy storage system and the corresponding charging characteristics for the operating conditions at the sectioning post. On the example of the section under consideration, the dependence of the discharge depth of the electric energy storage system on the nominal energy intensity is shown. Based on the results of calculations, an evaluation was made of the options for passing train batches in the even and odd direction in comparison with the schedule of the performed train operation. The range of variation of the nominal values of power and energy intensity of the electric energy storage system is obtained. Comparison of the accumulation system parameters for single- and double-track sections of railways, including those with a predominance of passenger traffic, is carried out.

TiO2 Nanotubes Architectures for Solar Energy Conversion

Electromagnetic light from the Sun is the largest source, and the cleanest energy available to us; extensive efforts have been dedicated to developing science and engineering solutions in order to avoid the use of fossil fuels. Solar energy transforms photons into electricity via the photovoltaic effect, generating about 20 GW of energy in the USA in 2020, sufficient to power about 17 million households. However, sunlight is erratic, and technologies to store electric energy storage are unwieldy and relatively expensive. A better solution to store energy and to deliver this energy on demand is storage in chemical bonds: synthesizing fuels such as H2, methane, ethanol, and other chemical species. In this review paper we focus on titania (TiO2) nanotubes grown through electrochemical anodization and various modifications made to them to enhance conversion efficiency; these semiconductors will be used to implement the synthesis of H2 through water splitting. This document reviews selected research efforts on TiO2 that are ongoing in our group in the context of the current efforts worldwide. In addition, this manuscript is enriched by discussing the latest novelties in this field.

Development of an effective accumulator battery with a voltage inverter in the electric energy storage unit

The article proposes a matching device between an accumulator battery and a voltage inverter in electric energy storage systems based on a reversible DC-DC converter with improved weight, size and cost indicators. Lithium-ion batteries are subject to tough operational requirements. The discharge of such batteries is not recommended to exceed their three-fold capacity (C), while the charge is limited to 0.5C, and low-frequency ripple components should not be present in the charging current. These requirements can be fulfilled with the help of the proposed matching device which is characterized by smaller dimensions and cost achieved due to the choke unit. The article proposes the calculation of the converter circuit and presents the simulation results obtained in the Psim simulation environment (the PowerSim environment). An economic assessment of the converter has been carried out.