MIT engineers have discovered a remarkably simple new solution to the production and distribution of zero-emission fuel.
MIT researchers recently found that pure aluminum recovered from old soda cans, when combined with salt water, produces a bubbly hydrogen reaction that may serve as a potential fuel source. Crucially, this hydrogen gas could power engines and fuel cells without emitting carbon, a major driver of climate change. Not only is hydrogen produced, but thermal energy is also released in the reaction.
Clean Energy Through Recycling
As one of the most abundant metals in Earth’s crust, aluminum’s low cost and high availability make it even more attractive as a potential fuel source.
Aly Kombargi, Enoch Ellis, Peter Godart, and Douglas P. Hart reported their work in a new paper published in Cell Reports Physical Science. Although the surprising discovery will require more work before it can be practically implemented, progress continues.
According to the researchers, first, the aluminum is treated with a liquid metal gallium-indium eutectic, scrubbing it from the layer of aluminate oxide that normally protects it from corrosion. This naked aluminum is then mixed with salt water, which now can bypass the aluminum oxide layer and directly mix with the pure aluminum, creating the reaction that generates the hydrogen gas.
Aluminum contains a great deal of potential energy. By volume, it contains twice that of diesel fuel and forty times what a lithium-ion battery can store. With the discovery of their novel process, Kombargi, Ellis, and Godart have managed to unlock the abundant metal’s potential for practical use.
Solving the Recovery Hurdle
One drawback is that the high cost of gallium could limit the feasibility of implementing such a process. In recognition of this, the team also prioritized finding a means of making the new process cost-effective.
One of the most promising aspects of the process is that salt ions and gallium are attracted to one another, meaning that the salt can recover the gallium and allow the process to repeat itself in a sustainable cycle. The team tested several different solutions aimed at enhancing gallium recovery, revealing a few trade-offs, including stronger reactions leading to less gallium recovery. Still, many factors impact recovery rates, and the team is still working to refine the process.
Zero-Emission Fuel with A Caffeine Kick
The MIT researchers also made a surprise discovery when they tried adding a common and beloved source of caffeine into the mix. When coffee was added to the reaction, the researchers found that it produced as much hydrogen in only five minutes as it had previously required two hours to produce. Pursuing why the coffee acted as an accelerant, the team eventually isolated imidazole, a component of caffeine, as the key ingredient.
However, this wasn’t the only advantage of introducing coffee into the mix since caffeine was also revealed to have a dual property that mitigates the reaction speed versus recovery trade-off. The compound acts as both a catalyst and a bonding agent. In essence, this allows it to strengthen the reaction while also aiding in bonding valium particles back together for recovery.
The team has now begun work on designing a reactor based on the principles that they’ve discovered, which can be used to power a marine or submarine watercraft.
“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, a PhD student in MIT’s Department of Mechanical Engineering and the lead author of the recent study detailing the team’s findings.
Pellets of recycled aluminum alongside gallium-indium and caffeine will fill the reactor, which could then be flooded with external seawater as needed to produce the reaction. The hydrogen’s power could then be further converted into either thrust or electricity, as the vessel requires.
Safety Issues
While hydrogen has long been recognized as a potential green alternative to carbon-producing fossil fuels amidst the current climate crisis, it has some substantial drawbacks. Hydrogen is extremely flammable, and transporting quantities of hydrogen can present dangers to workers. The Center for Hydrogen Safety has recorded hundreds of accidents, including fatalities, relating to working with hydrogen dating back to the 1960s.
Beyond accidents, there are concerns about securing stored hydrogen to protect it from bad actors. Traditional natural gas pipelines in Iraq, for instance, have suffered hundreds of terrorist attacks. Only a few hundred hydrogen fueling stations currently exist, predominantly in Japan, Germany, Norway, and the United States, but the facilities are on track to expand rapidly in the coming decade. Spain is working to develop a network of more than 100 stations nationally by 2030. Each of these stations represents a potential target for terrorist groups. Whether the hydrogen is generated locally at stations, transported by pipeline, or hauled over land in tanker trucks, large quantities of it represent potential dangers.
Fortunately, the new process Kombargi, Ellis, and Godart have developed mitigates some of these concerns by generating hydrogen as needed, removing any requirement for the storage or transportation of this zero-emission fuel source.
The team’s study, “Enhanced Recovery of Activation Metals for Accelerated Hydrogen Generation from Aluminum and Seawater,” appeared in the journal Cell Reports Physical Science on July 25, 2024.