Patent ID: 7850034

Claim:
A method of separately storing and delivering a first gaseous fuel and a second gaseous fuel, said method comprising (a) liquefying the first gaseous fuel and containing said first fuel in liquefied form in a first space thermally insulated from the ambient environment at a storage temperature below said first fuel vaporization temperature; (b) pressurizing the second gaseous fuel and containing said second fuel in a second space thermally insulated from the ambient environment and within said first space at a storage pressure within a predetermined pressure range, said second fuel remaining in gaseous form at said storage temperature when said storage pressure is within said predetermined pressure range; (c) cooling said second fuel by thermal transfer between said first fuel contained within said first space and said second fuel contained within said second space; (d) delivering said first fuel from said first space on demand; and (e) delivering said second fuel from said second space on demand.