Development of hydrogen storage reactor using composite of metal hydride materials with ENG

Abstract

Hydrogen is widely accepted as a promising energy carrier replacing fossil fuels. In this context hydrogen storage is one of the critical challenges in realizing hydrogen economy which relies on hydrogen as the commercial fuel. Due to very low volumetric energy density of pure hydrogen, it is highly compressed as a gas phase or liquified at extremely low temperature. However, chemically combined state in other materials has advantages in terms of storage conditions and associated safety concerns.The present study focuses on a development of a hydrogen storage applicable to special fuel cell (FC) mobilities such as forklift but not limited to. We adopts a solid-state storage method using metal hydride composite prepared by processing La0.9Ce0.1Ni5 and extended natural graphite (ENG). The isothermal hydrogen absorption/desorption behavior of the composite is measured at 20–80 °C. The results suggest that around 10 bar is sufficient to store 1.2 wt% of hydrogen. A cylindrical reactor is manufactured and experiments are carried out with the fabricated hydrogen storage material by changing operation conditions. The results of satisfaction are obtained in terms of the amount of hydrogen storage (>83 standard liter) and the absorption time (~10 min) under relatively moderate conditions of temperature (~19 °C) and pressure (~11 bar).As for scaling-up, a reactor of 2.0 kWh is designed based on the experimental results. CFD analysis is performed based on the hottest operation conditions focusing on a cooling water flow. The flow pattern and the temperature distribution of the cooling water are expected to be adequate not deviating from the stable operating conditions. CFD would be further applied to optimize the incorporated modular reactors.