The team says the chemical reaction could be put to work powering engines or fuel cells in marine vehicles that suck in seawater.

Hydrogen is an important player in the game for decarbonizing energy production – it's clean-burning, energy-dense, and when used in fuel cells the only by-product is water. But one major hurdle is that it's hard to store and transport, because the tiny molecules tend to leak right through containers and piping. Not only does that mean losses, but excess hydrogen can wreak havoc in the atmosphere.

But future systems based on MIT's new technique could effectively produce hydrogen on demand right there in a vehicle. The only thing that would need to be carted around and stored would be aluminum pellets, which are far more stable and easier to work with.

In tests, a single pellet of aluminum weighing just 0.3 g (0.01 oz) placed in fresh, de-ionized water produced 400 ml of hydrogen in just five minutes. Scaled up, the team estimates that a single gram of pellets could generate an astonishing 1.3 L (0.3 gal) of hydrogen in five minutes.

The technique is based on a fairly simple chemical reaction: aluminum reacts very strongly to oxygen. So when you dunk it in water, it quickly strips the O out of H2O, leaving molecular hydrogen behind to bubble out. The problem is, this process usually doesn't last long. As it occurs, a thin layer of aluminum oxide builds up on the metal's surface, blocking the pure aluminum below from interacting with the oxygen any further.

Previous studies have found that mixing in other metals like gallium can take the brakes off, by breaking down the aluminum oxide layer as it forms. In this case, the team pretreated the aluminum pellets with an alloy of gallium and indium, which allowed the reaction to last longer.