Aluminum may be treated in a eutectic bath of gallium and indium to enable its reaction with water to produce hydrogen and heat. This “activated” aluminum can effectively be utilized as a safe, energy-dense method of storing hydrogen which may be particularly appealing as an energy source for marine applications where water is abundantly available from the surroundings. When activated aluminum is reacted slowly over long periods of time via a controlled injection of water we find that significantly less hydrogen is produced than when the reaction is allowed to carry out quickly. Using microtomography we show that the topology of the solid reaction byproduct depends heavily on the conditions under which the reaction takes place and that slowly reacted aluminum becomes encapsulated in dense solid byproduct, preventing it from being reacted fully. Using this knowledge, we design an improved reactor for the sustained production of hydrogen over long periods.
