Connect, no.63, January 1995, p.1
Natural gas is finding increasing use worldwide as an alternative fuel for motor vehicles
British Gas plc has been working with TWI to develop an alternative gas storage system for natural gas vehicles (NGVs).
Conventional natural gas vehicles run on compressed natural gas (CNG) stored in cylinders at a pressure of around 200bar. The amount of useful space occupied by these cylinders is a distinct drawback - particularly in smaller vehicles. British Gas has produced a new system where gas is adsorbed within a microporous carbon matrix, providing 2/ 3 the storage capacity of CNG at only 1/ 6 the storage pressure.
Reduced storage pressure provides the opportunity to design and build specially shaped non-cylindrical storage tanks giving greater packaging flexibility to onboard storage systems. TWI designed and manufactured experimental tanks which were rectangular rather than cylindrical in section - a 'briefcase' size and shape of tank was produced.
To achieve the desired shape with adequate pressure-containment capability, a cellular tank was considered essential. This led to the idea of forming the complete body of the tank from a single multicell extrusion in aluminium alloy. Despite the complexity of the design, extrusion was successfully achieved by Alcan Speciality Extrusions Ltd in Workington.