NOVELTY - The apparatus comprises a heater (16) for heating ammonia to convert it into gas, a reactor (22), which has a first path for containing a catalyst to facilitate conversion of ammonia into nitrogen and hydrogen and is housed in a chamber within a larger vessel, a first heat exchange arrangement (20) outside the reactor for heating the ammonia before it is passed into the reactor, and a second heat exchange arrangement (26) in the reactor including a second path in the reactor for passing nitrogen and hydrogen gases through the reactor in heat exchange relationship with the first path.    USE - Apparatus for converting ammonia gas into nitrogen and hydrogen gases useful in an electricity generating system (claimed).    ADVANTAGE - The apparatus is capable of economically, reliably and efficiently converting the ammonia gas into nitrogen and hydrogen gases with less energy consumption, and is compact.    DETAILED DESCRIPTION - The apparatus comprises a heater (16) for heating ammonia to convert it into gas, a reactor (22), which has a first path for containing a catalyst to facilitate conversion of ammonia into nitrogen and hydrogen and is housed in a chamber within a larger vessel, a first heat exchange arrangement (20) outside the reactor for heating the ammonia before it is passed into the reactor, and a second heat exchange arrangement (26) in the reactor including a second path in the reactor for passing nitrogen and hydrogen gases through the reactor in heat exchange relationship with the first path to effect further heating of the ammonia. The first arrangement has a pipe-in-pipe arrangement, where one of the pipes passes ammonia into the vessel and the other of the pipes receives gases from the reactor. The pipe-in-pipe arrangement follows tortuous path. The second arrangement is formed by an elongate solid body of thermally conducting material within which the paths are provided. The solid body provides a path for heat to be exchanged between the paths. The apparatus includes an induction heater for heating the solid body. Passageways are formed in the solid body, and include sets of passageways extending between first end region of the solid body and second end region of the solid body opposite to the first end region. The passageways in or each set of passageways are parallel to one another, are connected in series with one another, define the paths, and includes a passageway for containing the catalyst to catalyze the conversion of ammonia gas into nitrogen and hydrogen. Each set of passageways includes an elongate chamber with catalyst. A downstream end of the chamber is closed by a gas permeable closure to allow the passage of gas while obstructing the passage of solid catalyst. Each set of passageways includes a first upstream passageway extending from the first end region to the second end region, a second upstream passageway connected in series with the first upstream passageway and extending from the second end region to the first end region, and downstream passageway connected downstream of the elongate chamber. The upstream passageways are connected upstream of the elongate chamber. The solid body has core and sleeve fitted around the core, where some of the passageways are defined by channels formed between the periphery of core and sleeve. The channels include pair of channels connected to one another at the first end region of the solid body. The pair of channels defines the upstream passageways. The sets of passageways are angularly spaced around the longitudinal axis of the solid body. The solid body has circular cross-section, and a central portion extending from the first end region to the second end region, where the central portion defines an inlet pipe to convey ammonia to the sets of passageways and an outlet pipe to convey nitrogen and hydrogen gases out of the reactor. The inlet pipe enters the solid body in the first end region, extends through the central portion of the body, and opens into a chamber in the second end region. The chamber extends radially outwardly beyond the central portion of the end region of the body. The outlet pipe extends through the central region of the body around the inlet pipe, and leaves the solid body in the first end region of the solid body. The overall volume of the solid body is less than 10000 cm3. The vessel includes outer storage chamber for storing gases produced in the conversion of ammonia, and an inner chamber having a reactor to convert ammonia gas into nitrogen and hydrogen. The chamber housing the reactor is disposed within the outer storage chamber, and is a low pressure chamber. The top of the inside of the chamber is spaced from the top of the reactor. The first arrangement is disposed inside the vessel. The interior volume of the vessel is less than 1 m3. The reactor is located within the low pressure chamber. The apparatus has ammonia storage tank arranged within a container and connected to inlet and outlet valves, where access to the inlet valve and outlet valve is controlled by first lockable housing and second lockable housing, a unit for measuring the level of ammonia within the tank, and a unit for transmitting data from the measuring unit to a point outside of the container. The second lockable housing controls access to the ammonia storage tank. The data transmission unit is a wired- or wireless data transmission unit. The apparatus includes an induction heating arrangement for heating gases in the reactor, a fuel cell arranged to receive hydrogen, and a telecommunications mast forming a transmitter and receiver in a telecommunications system, where power for the mast is provided by the fuel cell. The highest temperature of the reactor is less than 200 degrees C above the highest temperature of the gases. The ammonia is converted into hydrogen and nitrogen in a first process and some ammonia remaining from the first process is converted into hydrogen and nitrogen in a second process different from the first process. The ammonia tank is connected to a filling port that is accessible without opening the container. INDEPENDENT CLAIMS are included for:    (1) an electricity generating system including a hydrogen fuel cell for generating electricity from hydrogen and an apparatus for generating hydrogen;    (2) a method of converting liquid ammonia into nitrogen and hydrogen gases,    (3) an apparatus for storing liquid ammonia; and    (4) a method of monitoring an apparatus for converting ammonia into nitrogen and hydrogen, contained within a container.    DESCRIPTION OF DRAWING(S) - The diagram shows a block diagram view of a cracking system.    Heater (16)    Dryer (18)    First heat exchange arrangement (20)    Reactor (22)    Second heat exchange arrangement. (26)