Operation of a Hydrogen Storage-Based Smart DC Microgrid

In this chapter, the author presents the operation and power management of the hydrogen storage-based smart DC microgrid (DCMG). In this microgrid, several renewable distributed generations (DGs) such as wind turbine, solar photovoltaic system, solid oxide fuel cell (SOFC), and battery energy storage system are interconnected together and to the various DC and AC loads to form a ring-type low voltage distribution network. An additional storage as Hydrogen storage system has been connected to the dc microgrid for balancing the power at all times in the DCMG, under islanded mode operation, for all practical cases. An architecture of the hydrogen storage-based DC microgrid is suggested mainly for the remote rural area. For the regeneration of the electricity from the stored hydrogen, a SOFC DG system is also used in the proposed DCMG. A control technique is also developed for the operation of the hydrogen storage-based DCMG. The proposed DCMG system provides a reliable and high-quality power supply and will supply the power to all loads (both DC and AC) simultaneously.

Recent Advances in Homogeneous/Heterogeneous Catalytic Hydrogenation and Dehydrogenation for Potential Liquid Organic Hydrogen Carrier (LOHC) Systems

Here, we review liquid organic hydrogen carriers (LOHCs) as a potential solution to the global warming problem due to the increased use of fossil fuels. Recently, hydrogen molecules have attracted attention as a sustainable energy carrier from renewable energy-rich regions to energy-deficient regions. The LOHC system is one a particularly promising hydrogen storage system in the “hydrogen economy”, and efficient hydrogen mass production that generates only benign byproducts can be applied in the industry. Therefore, this article presents hydrogenation and dehydrogenation, using homogeneous or heterogeneous catalysts, for several types of LOHCs, including formic acid/formaldehyde/ammonia, homocyclic compounds, nitrogen- and oxygen-containing compounds. In addition, it introduces LOHC system reactor types.

Hydrogen-based electricity storage optimization on buildings by coupling thermal and photovoltaic electricity production towards carbon neutrality

Self-sufficiency (SS) of buildings with low greenhouse gas (GHG) emissions can be obtained using photovoltaics (PV). To maximize self-consumption - minimizing the import of grid electricity - PV can be coupled with a hydrogen storage system converting the electricity to hydrogen by electrolysis during the summer season, when the on-site production is higher, and using it during the winter season with fuel cells. This article deals with the sizing constraints of solar hydrogen systems at building-scale. The future building for the Smart Living Lab (SLL) in Fribourg (Switzerland) has been taken as case study. It has four stories and a mixed usage (Office-building and Research facilities), with a multi-oriented PV installation in order to produce enough electricity to achieve at least 50% of self-sufficiency. Using the PV production, this study aims to optimise the sizing of a hydrogen storage system allowing to reach the required self-sufficiency ratio. Finally, a comparison of the global efficiency of the system for three different demand-side scenarios.

The Improvement in Hydrogen Storage Performance of MgH2 Enabled by Multilayer Ti3C2

MgH2 has become a hot spot in the research of hydrogen storage materials, due to its high theoretical hydrogen storage capacity. However, the poor kinetics and thermodynamic properties of hydrogen absorption and desorption seriously hinder the development of this material. Ti-based materials can lead to good effects in terms of reducing the temperature of MgH2 in hydrogen absorption and desorption. MXene is a novel two-dimensional transition metal carbide or carbonitride similar in structure to graphene. Ti3C2 is one of the earliest and most widely used MXenes. Single-layer Ti3C2 can only exist in solution; in comparison, multilayer Ti3C2 (ML-Ti3C2) also exists as a solid powder. Thus, ML-Ti3C2 can be easily composited with MgH2. The MgH2+ML-Ti3C2 composite hydrogen storage system was successfully synthesized by ball milling. The experimental results show that the initial desorption temperature of MgH2-6 wt.% ML-Ti3C2 is reduced to 142 °C with a capacity of 6.56 wt.%. The Ea of hydrogen desorption in the MgH2-6 wt.% ML-Ti3C2 hydrogen storage system is approximately 99 kJ/mol, which is 35.3% lower than that of pristine MgH2. The enhancement of kinetics in hydrogen absorption and desorption by ML-Ti3C2 can be attributed to two synergistic effects: one is that Ti facilitates the easier dissociation or recombination of hydrogen molecules, while the other is that electron transfer generated by multivalent Ti promotes the easier conversion of hydrogen. These findings help to guide the hydrogen storage properties of metal hydrides doped with MXene.

A COMPARISON OF THE EFFECTS OF SODIUM BOROHYDRIDE-BASED HYDROGEN STORAGE SYSTEM AND COMPRESSED HYDROGEN STORAGE TANK ON THE FUEL CELL VEHICLE PERFORMANCE

Thanks to its features such as being harmless to the environment, not creating noise pollution, and reducing oil dependence, many countries have started promoting the use of fuel cell vehicles (FCVs) and making plans on enhancing their hydrogen infrastructure. One of the main challenges with the FCVs is the selection of an effective hydrogen storage unit. Compressed gas tanks are mostly used as the hydrogen storage in the FCVs produced to date. However, the high amount of energy spent on the compression process and the manufacturing cost of high-safety composite tanks are the main problems to be overcome. Among different storage alternatives, boron compounds, which can be easily hydrolyzed at ambient temperature and pressure to produce hydrogen, are promising hydrogen storage materials. In this study, a 700-bar compressed gas tank and a sodium borohydride (NaBH4)-based hydrogen storage system are compared for a passenger fuel cell vehicle in terms of the range of the vehicle. The energy storage and production system of the FCV were modeled in MATLAB Simulink® environment coupling the modeling equations of each component after finding the power requirement of the vehicle through vehicle dynamics. Then, the simulations were performed using the speed profile of the New European Drive Cycle (NEDC) and the acceleration requirements. According to the simulation results, the NaBH4-based hydrogen storage system provided a 4.42% more range than the compressed gas tank.