may alternatively or additionally be bubbled through the fuel as illustrated in fig1 repositioning the thermal conductor relative to the fuel and or fuel container may be used as a means of adjusting the rate of fuel vaporization and may be performed manually or automatically using for example a bimetallic strip or a solenoid or motor the composition and dimensions of the thermal conductor including a diameter cross section length materials coatings etc may vary the heating output in addition to the repositioning of the thermal conductor the amount of heat conducted will depend on the depth mass of the fuel in the fuel container for example as illustrated in fig6 a thermal conductor may be a modified thermal conductor 17 such that the shape varies the amount of heat transferred into the fuel based on the mass of the fuel remaining fig4 illustrates an exemplary embodiment in which the thermal conductor is positioned within the liquid or gel fuel by one or more compression springs 11 which transfers heat from the catalyst and membrane or porous media to the liquid or gel fuel 5 until the thermally activated springs 16 are heated to a temperature which causes the thermally activated springs to pull a part of the thermal.