Tanya Weaver Fri 26 Jul 2024
Collected at: https://eandt.theiet.org/2024/07/26/hydrogen-power-vehicles-produced-using-three-simple-ingredients-aluminium-cans-seawater
Researchers have developed a new, sustainable method to produce hydrogen gas that uses easily accessible materials including aluminium soda cans, seawater and coffee grounds.
The team from Massachusetts Institute of Technology (MIT) in Boston, believe the process could be a good, low carbon way to produce hydrogen for use in vehicles.
The risk with powering vehicles with a tank full of hydrogen gas is that it is volatile and highly explosive, so the team looked for ways to use the fuel without having to transport it onboard.
They discovered that when aluminium comes into contact with water, it undergoes a straightforward chemical reaction that generates hydrogen and heat.
However, as soon as the aluminium is out the water and exposed to oxygen, the surface immediately forms a thin layer of aluminium oxide, blocking the pure aluminium from interacting with the oxygen.
Inspired by previous work in which aluminium’s shield could be pierced with an alloy made from gallium and indium. Unfortunately, the process requires a significant amount of gallium and indium alloys which are both relatively rare and expensive.
To overcome this and allow the rare materials to be more easily reused, the team pre-treated pebble-sized aluminium pellets with this alloy and dropped them into the solution – enabling the reaction to last longer.
The aluminium pellets were found to react with the ions to generate hydrogen, which, in turn, attract the alloys that clump together in a form that can be easily scooped out. The alloys can then be reused to generate more hydrogen, in a sustainable cycle.
Conveniently, seawater is an ionic solution that is cheap and available.
“I literally went to Revere Beach with a friend and we grabbed our bottles and filled them, and then I just filtered out algae and sand, added aluminium to it, and it worked with the same consistent results,” described study lead author Aly Kombargi, a PhD student at MIT.
However, while the hydrogen indeed bubbled up when aluminium pellets were added to a beaker of filtered seawater, and the gallium indium could be scooped out afterward, the action happened very slowly.
Having experimented with a number of ingredients to speed up the reaction they then stumbled across a common stimulant: caffeine in the form of coffee grounds.
The team discovered that a low concentration of imidazole — an active ingredient in caffeine — is enough to significantly speed up the reaction, producing the same amount of hydrogen in just five minutes, compared to two hours without the added stimulant.
Kombargi said: “That was our big win, we now had everything we wanted: recovering the gallium indium, plus the fast and efficient reaction.”
A pebble-sized pellet of aluminium, dropped into a beaker of filtered seawater, produces hydrogen gas that bubbles up and out of the container within a few minutes.
The researchers are now developing a small hydrogen reactor in which hydrogen is produced on demand with aluminium as the ‘fuel’ and seawater added to it.
They plan to initially test it on marine and underwater vehicles and estimate that a reactor, holding about 40 pounds of aluminium pellets, could power a small underwater glider for about 30 days by pumping in surrounding seawater and generating hydrogen to power a motor.
“The next part is to figure out how to use this for trucks, trains, and maybe airplanes. Perhaps, instead of having to carry water as well, we could extract water from the ambient humidity to produce hydrogen. That’s down the line,” concluded Kombargi.
Leave a Reply