In a stunning find engineering feat, MIT engineers have cracked how to create hydrogen fuel from the most commonplace components such as soda cans, seawater, and even coffee grounds. It shifts the goalpost in clean-energy production, specifically within marine applications.
This research, published in the journal Cell Reports Physical Science, shows that aluminum under its native configuration, when exposed and mixed with seawater, naturally liberates hydrogen gas. This gas can then power engines or fuel cells with no creation of carbon emissions. The addition of caffeine, a universal stimulant present in coffee, further accelerates the process.
The group found out that dropping pretreated, pebble-sized aluminum pellets into filtered seawater releases hydrogen gas. The aluminum is pretreated with a rare-metal alloy that scours it to pure form for reaction with the seabed. The salt ions of the seawater help recover the alloy to make the process sustainable.
What they discovered was that the aluminum’s reaction with seawater was slow at first, and then coffee grinds were poured in. The imidazole, a derivative of the active ingredient in coffee, caffeine, reduced the same hydrogen produced in five minutes if they were not present, in their presence it was produced in two hours.
“This is very interesting for maritime applications like boats or underwater vehicles because you wouldn’t have to carry around seawater, it’s readily available,” said Aly Kombargi, the study’s lead author and a PhD student in MIT’s Department of Mechanical Engineering. “We also don’t have to carry a tank of hydrogen. Instead, we would transport aluminum as the ‘fuel,’ and just add water to produce the hydrogen that we need.”
The research team, led by MIT professor Douglas Hart in mechanical engineering, is working on a small reactor that could find its way into marine vessels or underwater vehicles. Such a reactor would hold recycled aluminum pellets from old soda cans, a small amount of gallium-indium alloy, and a little caffeine. These ingredients could then be periodically added to the reactor, along with seawater, to produce hydrogen on demand. It could then be fed through an onboard engine or be utilized to generate electricity that would be used to propel the vessel.
Among the authors are undergraduate chemical engineering students Enoch Ellis and Peter Godart, who have started a company that aims to recycle aluminum as a source of hydrogen fuel.
Hydrogen is so reactive that it’s hard to store or carry. The MIT team got around that by using aluminum, which is stable but can generate hydrogen upon contact with water. Aluminum naturally exposes itself to air and develops a thin oxide layer that prevents any further reactions. The researchers used a pretreatment of the aluminum by a gallium-indium alloy, which gets under the oxide.
In their previous experiments under fresh water, the team used to get 400 milliliters of hydrogen in only 5 minutes, from one pre-treated aluminum pellet. They go on to argue that one gm pellet would produce 1.3 liters of hydrogen in a similar timescale. By any stretch of the imagination here, one would need an enormous quantity of that rare and expensive gallium-indium alloy to scale up the system.
However, based on the findings, they managed to retrieve and reuse the alloy inexpensively and sustainably by using ions present in seawater. “Luckily, seawater is already very cheap and available ionic solution,” Kombargi shared. He tested the idea using seawater from a beach near his lab and received similar results.
“I think we now have the critical ingredients of a safe, powerful, and really simple way to represent a sustainable hydrogen reactor,” said one of the researchers. “We will test it first in marine and underwater vehicles.” They calculate the reactor would have about 40 pounds of aluminum pellets and be capable of running a small underwater glider for about 30 days by pumping in surrounding seawater and generating hydrogen to power a motor.
“This is to show a new way of producing hydrogen fuel, without carrying hydrogen, but carrying aluminum as ‘fuel,'” Kombargi said. “The next part is to know how to use this for trucks, trains, and maybe airplanes. Perhaps instead of having to carry the water as well, we could extract water from the ambient humidity to make hydrogen. That’s down the line.”
One can only imagine how such innovation would pave the way for new, much-needed, more sustainable, and more efficient routes for producing hydrogen and prove to be a very promising solution for clean energy applications.