GKN says that it has developed a demonstrator system of its hydrogen storage system for residential homes using metal hydride powder.

The company aims to provide an integrated zero emission heat and energy storage system for an off-grid alpine chalet with a system capacity of above 130 kW, equivalent to providing a normal four-person household for about 12 to 14 days with electrical power and no recharging. The company also plans to re-use the process temperature for heating. According to GKN, the project is among the first in the world to use metal hydride pallets for hydrogen storage in a residential application.

Typically, hydrogen is stored as gas and requires very large storage tanks operated at high pressure up to 300 bars. Using metal powder as a medium to store hydrogen means that amount of hydrogen gas can be stored in a tank not even half the size compared to gas. Additionally, the metal powder based process works at a lower pressure and is easier to control in terms of temperature levels. In GKN’s process, the storage tanks are loaded with hydrogen gas at pressure levels below 40 bars. The pelletized metal alloy inside the tank reacts with hydrogen and builds metal hydrides.

Loading the tank with hydrogen is an exothermic process, so that absorption of hydrogen into the metal framework of the tank needs to be cooled and maintained at 20°C to keep the loading process stable and efficient. For unloading or desorption, the tank needs to be heated up to 60°C as the chemical reaction to remove hydrogen out of the metal lattice is endotherm. The higher the flow of hydrogen into or out of the tank, the more intensive is the chemical reaction. To increase the kinetic capacity for quick loading and unloading and for safety reasons, thermal management is a key aspect of the metal hydride-tank-system. GKN engineers worked on double tube tanks to improve heat transfer between the active material and the cooling/heating media. The new tank design reportedly speeds up processes and reduces energy losses for heating and cooling.

‘GKN Powder Metallurgy is on the way to utilizing a well-known chemical process and material capability of metal hydride and bringing it to a new level for a real-life residential application,’ the company said in a press release. ‘This will help reduce CO2 levels and bring the opportunity to better utilize natural non-carbon energy sources like wind, water and sun.’

This story uses material from GKN, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.