A method of operating a reductant delivery and storage system of a vehicle, comprising of storing an ammonia-containing fluid in a first storage device, generating ammonia vapors in the first storage device and storing said generated ammonia vapors in a second storage device, purging said stored vapors from the second storage device to an exhaust of the engine, delivering said ammonia-containing fluid to said exhaust of the engine, and adjusting at least one of an amount of ammonia-containing fluid delivered and an amount of vapors purged to said exhaust based on the other of said at least one of said amount of ammonia-containing fluid delivered and said amount of vapors purged to said exhaust.