MIT Team Creates Clean Hydrogen with Seawater, Soda Cans, Caffeine | Sustainable Brands (2025)

The engineers believe they have discovered the recipe for running a sustainablehydrogen reactor, which they plan to test first in marine and underwatervehicles.

A research team atMIThas discovered a simple, low-cost, sustainable method for creating cleanhydrogen — with just seawater, soda cans and caffeine.

The team of engineers found that when the aluminum in soda cans is exposed inits pure form and mixed with seawater, the solution bubbles up and naturallyproduces hydrogen — a versatile gas that can be used to power an engine or fuelcell without generating carbon emissions. What the team also discovered is thatthis simple reaction can be sped up by adding a common stimulant: caffeine.

When exposed to air or water, pure aluminum instantly forms a protective,aluminum-oxide skin that keeps it from reacting with water: “This is why whenyou put a soda can in water, it doesn’t react,”explainsAly Kombargi — a PhD student inMIT’s Department of Mechanical Engineering and lead author of the study.

As described in Cell Reports PhysicalScience,the researchers were able to prevent this reaction and produce hydrogen gas bydropping pre-treated, pebble-sized aluminum pellets into a beaker of filteredseawater. The aluminum was pre-treated with a rare-metal alloy — a mix ofgallium and indium — that prevents the formation of aluminum oxide,leaving pure aluminum that can react with seawater to generate hydrogen. Thesalt ions in the seawater can in turn attract and recover the alloy, which canbe reused to generate more hydrogen, in a closed loop.

The team found that while this reaction between aluminum and seawatersuccessfully produces hydrogen gas, it was a slow process. On a lark, they addedcoffee grounds to the mix and were surprised to see that it sped up thereaction. Turns out, a low concentration of imidazole, an active ingredientin caffeine, is enough to significantly speed up the reaction — producing thesame amount of hydrogen in just five minutes, compared to two hours without thestimulant.

The researchers are developing a small reactor that could run on a marine vesselor underwater vehicle. The vessel would hold a supply of aluminum pellets(recycled from old soda cans and other aluminum products), along with a smallamount of the gallium-indium mix and caffeine. These ingredients could beperiodically funneled into the reactor, along with some of the surroundingseawater, to produce hydrogen on demand — which could then power an onboardengine or generate electricity to power the ship.

“This is very interesting for maritime applications like boats or underwatervehicles, because you wouldn’t have to carry around seawater — it’s readilyavailable,” Kombargi says. “We also don’t have to carry a tank of hydrogen.Instead, we would transport aluminum as the ‘fuel,’ and just add water toproduce the hydrogen that we need.”

Pitfalls of conventional hydrogen production and use

A fully decarbonized energy system will require both clean electrification andlow-carbon fuels, and clean hydrogen holds greatpromisein enabling us to achieve a net-zero future — if we are able to efficiently andeffectively scale its production. Hydrogen is increasingly seen as a potentialsubstitute for fossilfuels,especially in energy-intensive processes that cannot easily be fueled byelectricity — such as blast furnaces, cement works and industrial heating — andlong-distance aviation and shipping.

But until now, hydrogen has had to be manufactured — usually by separating itfrommethane,which requires a lot of energy — which means it is only as clean as the energysources used to make it. Most of the 70 million tons of hydrogen currently usedglobally each year by industry is derived from fossil fuels, giving it a largecarbon footprint.

Energy companies such as Vattenfall are demonstrating the promise andviability of fossil-freehydrogen,but the International Energy Agency estimates we’ll need a six-foldincrease in clean hydrogenproductionto achieve net zero by 2050.

The research team — led by DouglasHart, MIT professor ofmechanical engineering — is developing efficient, sustainable methods to producehydrogen gas. The study’s co-authors also include EnochEllis, an undergraduate in chemicalengineering; and Peter Godart, whoearned his Mechanical Engineering PhD at MIT in 2021 and has co-founded FoundEnergy — a startup that recycles aluminum as asource of hydrogen fuel.

One barrier to fueling vehicles with hydrogen at scale is that some designswould require the gas to be carried onboard, like gasoline in a tank — a riskysetup, given hydrogen’s volatile potential. Hart and his team have looked forways to power vehicles with hydrogen without having to constantly transport thegas itself. Their aluminum-seawater-caffeine process is a promising workaround;but viability of the new system at scale would require a significant supply ofgallium-indium, which is relatively expensive and rare.

“For this idea to be cost-effective and sustainable, we had to work onrecovering this alloy post-reaction,” Kombargi says.

Closing the loop

The team found they could retrieve and reuse gallium-indium using a solution ofions, which protect the metal alloy from reacting with water and help it toprecipitate into a form that can be scooped out and reused.

“Lucky for us, seawater is an ionic solution that is very cheap and available,”saidKombargi, who was able to duplicate the results with seawater from a nearbybeach.

The researchers believe they have discovered the recipe for running asustainable hydrogen reactor, which they plan to test first in marine andunderwater vehicles. They’ve calculated that such a reactor — holding about 40pounds of aluminum pellets — could power a small, underwater glider for roughly30 days by pumping in surrounding seawater and generating hydrogen to power themotor.

“We’re showing a new way to produce hydrogen fuel, without carrying hydrogen butcarrying aluminum as the ‘fuel,’” Kombargi says. “The next part is to figure outhow to use this for trucks, trains and maybe airplanes. Perhaps, instead ofhaving to carry water as well, we could extract water from ambienthumidityto produce hydrogen. That’s down the line.”