The Significance of Energy Storage for Renewable Energy Generation and the Role of Instrumentation and Measurement

International audienceEnergy storage is not a new concept but is currently getting increasing importance in the context of energy transition paradigm. Indeed, it is expected to play a key role as an enabling technology for lowering the carbon footprint of the electric power system. In fact, the growing development of renewable energy resources and their increasing share in the energy mix, are introducing significant challenges to the existing power grid due to the high variability of these sources/loads. In particular, maintaining the generation-consumption balance of the electric power in real time, as well as the overall power system security, when these special energy sources/loads are present at a significant scale is a major concern. With competitive energy storage, it will be possible to introduce more flexibility in the electrical system thus helping it to better manage the overall energy balance with better system response in case of severe contingencies. Energy storage technologies were historically used for managing the load curve while observing generation dynamic constraints. The most well-known storage technology is the pumped hydro storage where the energy is stored in a hydraulic form (water potential energy). With the event of open access and the corresponding unbundling of electric power industry segments, valorizing energy storage options under market conditions has become tricky. The major present barriers for deploying energy storage systems (ESS) are high cost, competitive economic value, efficiency and energy density, together with energy policies. The new energy paradigm has put a new emphasis on energy storage, and many research roadmaps have pointed out the need for overcoming the current barriers. The decision makers' awareness of the importance of energy storage is also on the rise. However, adequate incentives for encouraging massive deployment of ESS and storage technology within the electric power system are still lacking. Currently, most of the effort is dedicated to in situ demonstration projects in striving for smarter grids and support of innovations with the corresponding proofs of concept and feedback experience. Additionally, different grid applications are assessed for both centralized to decentralized uses. Various energy storage applications for frequency regulation, voltage support, investment optimization, or peak shaving are under consideration. In this article, some of the main energy storage technologies will be reviewed according to their main application domains. That will be followed by a focus on battery energy storage. Some key elements of battery management system (BMS) technologies and ESS architecture and characterization will be addressed. Then some aspects of ESS protection will be presented and the key trends and indications of emerging concepts for energy storage will be identified

Optimal Scheduling of Battery Energy Storage System in Distribution Network Considering Uncertainties using hybrid Monte Carlo- Genetic Approach

This paper proposes a novel hybrid Monte Carlo simulation-genetic approach (MCS-GA) for optimal operation of a distribution network considering renewable energy generation systems (REGSs) and battery energy storage systems (BESSs). The aim of this paper is to design an optimal charging /discharging scheduling of BESSs so that the total daily profit of distribution company (Disco) can be maximized. In this study, the power generation of REGSs such as photovoltaic resources (PVs) and the network electricity prices are studied through their uncertainty natures. The probability distribution function (PDF), is used to account for uncertainties in this paper. Also, the Monte Carlo simulation (MCS) is applied to generate different scenarios of network electricity prices and solar irradiation of PVs. Optimal scheduling of BESSs can be performed by genetic algorithm (GA). In this paper, firstly, the charging and discharging state of BESSs (positive or negative sign of battery power) is determined according to the variable amount of the electricity prices and power produced from PVs, which have been obtained from the Monte Carlo simulation. Then by using the GA, optimal amount of BESSs is determined. Therefore, a hybrid MCS-GA is used to solve this problem. Numerical examples are presented to illustrate the optimal charging/discharging power of the battery for maximizing the total daily profit

Electrodeposition of Nickel-Based Non-Noble Transition Metal Compounds for Electrocatalytic Water Splitting

Electrochemical water splitting has become increasingly important in energy-related applications. Especially, efficient storage of the electrical energy harvested from the sunlight and from wind in chemical bonds is crucial for a future renewable energy economy. The overpotentials for the hydrogen and the oxygen evolution reactions (HER, OER) are standardly reduced by employing rare and expensive metal-based catalysts. The replacement of these materials by abundant and low-cost alternatives is therefore of utmost technological importance. In the present work, Ni-based non-noble transition metal compounds such as Ni metal and its hydroxides and oxides as nanoparticles (NPs) and/or thin films as well as highly porous mixed Ni-Mo films were investigated for the electrocatalytic HER, OER and the overall water splitting reaction. They were prepared by employing electrochemical deposition techniques. The surface chemical composition and morphology of the synthesized materials were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. These analyses were carried out before and after the electrochemical reactions in order to gain a deeper understanding of the critical parameters for the catalytic activities. For the composite Ni/NiO/Ni(OH)2 NPs, the catalytic activity for the HER increases with an increase in the amount of NiO and reaches a maximum at the right composition of the active sites with approximately 25% Ni metal and Ni(OH)2 each, as well as 50% NiO. For the OER, a pre-treatment of the electrodeposited Ni(OH)2 films by thermal annealing in normal atmosphere is of extreme importance to form a large amount of the catalytically most active NiOOH species during the electrochemical reaction. As bifunctional electrocatalysts for the water splitting reaction, porous Ni-Mo structures were synthesized and investigated. In summary it can be stated, that the here prepared and tested Ni-based catalysts show activities comparable to the Pt for the HER and even better than the commercial RuO2 for the OER, respectively. Finally, the stabilities of the newly synthesized catalyst materials were investigated in relation to their activities and chemical compositions. Long-term measurements (up to 30 h) on the Ni composite NPs for the HER show a gradual transformation of the highly active catalyst compound consisting of Ni0, NiO, and Ni(OH)2 into the almost pure less-active Ni(OH)2 phase, which requires then the double overpotential to keep the current density at -10 mA cm-2. In contrast, the stability test of the annealed Ni(OH)2 films for the OER indicates an activation during the first 2 h with a corresponding decrease in overpotential, which is associated with the formation of the catalytically active NiOOH species. After the activation, the OER catalyst exhibits excellent electrochemical stability during the following 24 h