• Energy Research

AbstractThe integration of various renewable energy sources as well as the liberalization of electricity markets are established facts in modern electrical power systems. The increased share of renewable sources within power systems intensifies the supply variability and intermittency. Therefore, energy storage is deemed as one of the solutions for stabilizing the supply of electricity to maintain generation-demand balance and to guarantee uninterrupted supply of energy to users. In the context of sustainable development and energy resources depletion, the question of the growth of renewable energy electricity production is highly linked to the ability to propose new and adapted energy storage solutions. The purpose of this multidisciplinary paper is to highlight the new hydrogen production and storage technology, its efficiency and the impact of the policy context on its development. A comprehensive techno/socio/economic study of long term hydrogen based storage systems in electrical networks is addressed. The European policy concerning the different energy storage systems and hydrogen production is explicitly discussed. The state of the art of the techno-economic features of the hydrogen production and storage is introduced. Using Matlab-Simulink for a power system of rated 70kW generator, the excess produced hydrogen during high generation periods or low demand can be sold either directly to the grid owners or as filled hydrogen bottles. The affordable use of Hydrogen-based technologies for long term electricity storage is verified.

This article investigates the optimal efficiency of a photovoltaic system based on a silicon thin film tandem cell using polymorphous and microcrystalline silicon for the top and bottom elementary cells, respectively. Two ways of connecting the cells are studied and compared: (1) a classical structure in which the two cells are electrically and optically coupled; and (2) a new structure for which the “current-matching” constraint is released by the electrical decoupling of the two cells. For that purpose, we used a computer simulation to perform geometrical optimization of the studied structures as well as their electrical performance evaluation. The simulation results show that the second structure is more interesting in terms of efficiency.

In this paper, two energy management strategies considering the hydrogen consumption of hybrid power sources using a PEM Fuel Cell (FC) and Ultracapacitors (UC) are described and compared. First, the Hybrid Electric Vehicle (HEV) architecture and the associated models with their control strategies are described. The two energy management strategies are evaluated based on the Energetic Macroscopic Representation (EMR). The comparison focuses on the global efficiency of the power sources energy management. In particular, a proposed strategy is to manage the UC State-OfCharge while stabilizing the FC around its maximal efficiency point. Finally, some simulations on a Fuel Cell / Ultracapacitors HEV show the differences between the compared control strategies.

Fuel cell-based power sources are attractive devices. Through multi-stack architecture, they offer flexibility, reliability, and efficiency. Keys to accessing the market are simplifying its architecture and each components. These include, among others, the power converter enabling the output voltage regulation. This article focuses on this specific component. The present paper gives a comprehensive overview of the power converter interfaces potentially favorable for the automotive, railways, aircrafts and small stationary domains. First, with respect to the strategic development of a modular design, it defines the specifications of a basic interface. Second, it inventories the best architecture opportunities with respect to these requirements. Based on this study, it fully designs a basic module and points out the outstanding contribution of the new developed silicon carbide switch technology. In conclusion, this review article exhibits the importance of choosing the right power converter architecture and the related technology. In this context it is highlighted that the output power interface can be efficient, compact and modular. In addition, its features enable a thermal compatibility with many ways of integrating this component in the global fuel cell based power source.

Many reasons may cause malfunction of a proton exchange membrane fuel cell (FC) stack. Moreover, a single defect cell can affect the whole stack functioning; therefore, the localization of this cell is crucial as well as identifying the root causes for such malfunctioning. The diagnosis tool has to be nonintrusive and easy to replicate to a new FC system. This paper explores paths to achieve such monitoring based on the use of the magnetic field induced by the FC stack internal currents. Designing and using a 3-D simulation tool allows to establish a cause and effect relationship between FC defects and specific magnetic signatures. This preliminary work enables to determine the required magnetic sensor accuracy, the sensor orientation and location as well as the experimental precautions for relevant measurements.