NOVELTY - A start module comprises co-operatively engageable micro component heat exchangers with micro channels that direct laminar flow of fluid onto opposite sides of a separator. The heat exchangers are operatively interconnected with switchable sources of hydrogen and liquid hydrocarbons.    USE - For initiating the on-demand start-up of a hydrogen gas producing cycle, used for powering a fuel cell system.    ADVANTAGE - The novel system enables a reliable and efficient quick start for a steam reforming process, used for powering hydrogen fuel cells in automotive, mobile and other on-demand applications. It provides an instantaneous burst of energy to initiate a hydrogen producing cycle, and reduces the volume and quantity requirements for hydrogen storage in the system.    DETAILED DESCRIPTION - A start module comprises co-operatively engageable micro component heat exchangers with micro channels that direct laminar flow of fluid onto opposite sides of a separator. The heat exchangers are operatively interconnected with switchable sources of hydrogen and liquid hydrocarbons in a relationship in which: in a start mode, a first side of the first heat exchanger is interconnected with the source of hydrogen, and its second side is interconnected with the source of liquid hydrocarbons. Upon opening of the switches, hydrogen and hydrocarbons are introduced to the respective first and second sides of the heat exchanger. The first side provides instantaneous heat energy to the second side to vaporize the introduced hydrocarbons. The second side is interconnected with the second heat exchanger, such that vaporized hydrocarbons are introduced to a first side of the second heat exchanger to provide heat energy to vaporize hydrocarbons that are introduced to its second side. The second side of the heat exchanger is interconnected with the gas producing cycle, such that vaporized hydrocarbons exiting from the second side are introduced into the hydrogen producing cycle as an energy source for combustors, and as a feedstock component for the production of hydrogen. Upon initiation of the gas producing cycle, the first side of the second heat exchanger is connected to the off-gas from the fuel cell system and the flow of hydrogen towards the first side. The flow of hydrocarbons to the second side of the first heat exchanger is then switched off.    DESCRIPTION OF DRAWING(S) - The figure is a schematic diagram of an ignition system, as above.    Heat exchangers (1, 2)