MIT team brews up hydrogen fuel using soda cans, seawater and … coffee grounds

A team of engineers at MIT searching for sustainable ways to create hydrogen have found that mixing recycled aluminum soda cans, seawater and, surprisingly, coffee grounds creates a reaction that produces the gas that can drive an engine or fuel cell without generating carbon emissions.

The catch is that the old aluminum must be pretreated with a rare metal alloy that renders the aluminum into a pure state. But the researchers say that salt ions in the seawater will be able to attract and recover the precious alloy in the reaction, which can then be used to create more hydrogen in a sustainable cycle.

The coffee grounds? On a whim the researchers through them into the seawater mix during testing and discovered the reaction time sped up, producing the same volume of gas in five minutes as produced in two hours without the grounds. They found that a low concentration of imidazole — an active ingredient in caffeine — is enough to significantly speed up the reaction,

“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,” says study lead author Aly Kombargi, a Ph.D student in MIT’s Department of Mechanical Engineering, in an article on the MIT News website.

“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,” he said.

The researchers are developing a small reactor that could run on a marine vessel or underwater vehicle. The vessel would hold a supply of aluminum pellets (recycled from old soda cans and other aluminum products), along with a small amount of gallium-indium and caffeine.

These ingredients could be periodically funneled into the reactor, along with some of the surrounding seawater, to produce hydrogen on demand. The hydrogen could then fuel an onboard engine to drive a motor or generate electricity to power the ship.

The study’s co-authors include Enoch Ellis, an undergraduate in chemical engineering; Peter Godart Ph.D ’21, who has founded a company to recycle aluminum as a source of hydrogen fuel; and Douglas Hart, MIT professor of mechanical engineering. Their study was reported in the journal Cell Reports Physical Science.

The MIT team, led by Hart, is developing efficient and sustainable methods to produce hydrogen gas, which is seen as a “green” energy source that could power engines and fuel cells without generating climate-warming emissions.

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