Energetic evaluation of hydrogen storage in metal hydrides

Abstract

Summary Metal hydrides are considered as promising candidates for hydrogen storage as they exhibit higher energy densities than compressed gas storage storages. This study represents a theoretical thermodynamic analysis of metal hydride‐based hydrogen storage systems, focusing mainly on the energy demand to operate the storage system and the resulting efficiency. The main energy demand occurs during hydrogen release. This energy demand is composed of three contributions: the heat required to heat the hydride up to desorption temperature, the heat of reaction and the work of compression to reach the targeted outlet pressure. A sensitivity analysis was performed to demonstrate the impact of several parameters, for example, heat of reaction and hydrogen uptake on the energy balance. The most influential parameter is the heat of reaction. The hydrogen uptake does not have a noticeable influence as long as it is not too low. Several possibilities to improve the efficiency of the storage system are discussed (heat integration and the application of a heat storage system). Heat integration can significantly improve the overall efficiency, whereas the application of a heat storage system does not seem realistic. Compared with other hydrogen storage technologies, metal hydrides can feature higher efficiencies than low‐temperature hydrogen storage concepts, for example, liquefied or cryo‐adsorbed hydrogen. The efficiencies of a metal hydride storage system are similar to those reached with a system based on liquid organic hydrogen carriers. Copyright © 2016 John Wiley & Sons, Ltd.

High‐pressure hydrogen storage properties of Ti x Cr 1 − y Fe y Mn 1.0 alloys

“…The metal hydride compressor has the advantages of no mechanical moving parts, no noise, and so on, which can absorb hydrogen at low temperature and low pressure (better than the MIL‐101 + Pt/C materials which need high pressure at 233‐298 K for hydrogen absorption) and relax high‐pressure hydrogen at high temperature . The P d of the hydrides obtained by Ti 1.05 Cr 0.75 Fe 0.25 Mn 1.0 and Ti 1.02 Cr 0.85 Fe 0.15 Mn 1.0 absorbing hydrogen can be up to 45 MPa at 333 K (see in Tables ).…”

“…Compared with the 70-MPa tank (40.8 kg/m 3 ), 68 the ρ v of the hybrid system can achieve greater density about 52 kg/m 3 at lower pressure and cost, which is beneficial for an extended range of the fuel cell vehicle. Compared with the NaAlH 4 system, the hybrid tank can operate at low temperature (243 K), whereas the NaAlH 4 system usually operates at 433 to 473 K, because of the high decomposition temperature of Na 3 AlH 6 to NaH and Al,69 so the metal hydrides system can feature higher energy efficiency in agreement with Müller et al's research 70. Compared with the hybrid tank filled of (Zr 0.7 Ti 0.3 ) 1.04 Fe 1.8 V 0.2 alloy (hydrogen capacity of the alloys: 1.51 wt%, dissociation pressure of the hydride: 0.312 MPa at 243 K),36 herein, the tank filled of Ti x Cr 0.9 Fe 0.1 Mn 1.0 (x = 1.1, 1.05, 1.02) and Ti 1.05 Cr 0.9 Fe 0.1 Mn 1.0 alloys can achieve greater volumetric hydrogen density due to the higher hydrogen capacity absorbed in the alloys and have excellent hydrogen rate for fuel cell vehicle at low temperature (243 K) due to the high dissociation pressure of the hydride more than 1 MPa 62.…”

“…The metal hydride compressor has the advantages of no mechanical moving parts, 72 no noise, and so on, which can absorb hydrogen at low temperature and low pressure (better than the MIL-101 + Pt/C materials which need high pressure at 233-298 K for hydrogen absorption 73 ) and relax high-pressure hydrogen at high temperature. 70 hydrogen with the pressure 10 MPa was produced by a low-pressure stage compressor at 372 K from feed gas 4 MPa, and hydrogen with the pressure 45 MPa was produced by a high-pressure stage compressor at 372 K, 75 the tank filled with the alloys here still has the advantage of low operation temperature. The alloys filled in the tank can be as the compressor in the hydrogen refueling station, the heat exchange mainly occurs on the tank surface, and the heat transfer coefficient is 1000 W/m 2 /K with low temperature heat conducting oil.…”

Pd‐Ni/Cd loaded PPy/Ti composite electrode: Synthesis, characterization, and application for hydrogen storage

“…4,13,16 Hydrogen storage via chemical reactions is based on the covalent bonding of hydrogen on materials. 3 This type of material consists of ammonia, 3 formic acid, 1 boron-based hydrides, 17 metal hydrides, 18 and complex hydrides. 10 Storing hydrogen under electrochemical conditions is primarily achieved via cyclic voltammetry (CV), and the amount of absorbed hydrogen is related to the value of applied potential.…”

A review on design strategies for metal hydrides with enhanced reaction thermodynamics for hydrogen storage applications

“…31 Thus, considerable efforts have been dedicated to obtaining a comprehensive understanding of the properties of these systems and evaluating their potential as on-board hydrogen storage systems for vehicular applications. 1,2,[32][33][34][35][36][37][38][39][40][41][42] Such efforts have been primarily concentrated on improving the reaction thermodynamics associated with the release of hydrogen at mild temperatures.…”