Hydrogen holds the key to clean energy, but there’s a catch—most production methods are riddled with carbon emissions and high costs. What if we could flip the equation, turning waste into fuel with minimal environmental impact?
MIT researchers have cracked the code using the aluminum-water reaction (AWR), a process that leverages recycled aluminum, waste heat, and alloy recovery to generate hydrogen at a fraction of the conventional emissions, just 1.45 kg CO₂ equivalent per kilogram of hydrogen.
By examining the entire lifecycle of the process- from calculating the carbon emissions associated with acquiring and processing aluminum, reacting it with seawater to produce hydrogen, and transporting the fuel to gas stations, where drivers could tap into hydrogen tanks to power engines or fuel cell cars- they confirmed that this method slashes emissions compared to traditional hydrogen production.
Over its entire life cycle, this process emits only 1.45 kg of CO₂ per kilogram of hydrogen produced, a staggering contrast to fossil-fuel-based methods, which release 11 kg of CO₂ for the same amount of hydrogen.
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Lead author Aly Kombargi, PhD’25, who graduated this spring from MIT with a doctorate in mechanical engineering, said, “This work highlights aluminum’s potential as a clean energy source and offers a scalable pathway for low-emission hydrogen deployment in transportation and remote energy systems.”
Last year, the team found a clever workaround to aluminum’s natural resistance to reacting with water—by treating it with a small amount of gallium-indium. This rare metal alloy strips away its protective shield, exposing pure aluminum. When mixed with seawater, the exposed aluminum sparks a reaction that produces pure hydrogen.
The real magic? Salt in the seawater helps precipitate gallium-indium, allowing it to be recovered and reused, creating a cost-saving, sustainable cycle for continuous hydrogen production.
Kombargi explained that during conferences, the team frequently presented the science behind their hydrogen production process. However, the most common questions they received centered around cost and carbon footprint—key concerns for scalability and sustainability.
Making hydrogen out of seawater – no desalination required
Motivated by these inquiries, the researchers conducted a comprehensive analysis to ensure a thorough evaluation of the process from both economic and environmental perspectives.
Researchers set out to answer a question that has been lurking in the shadows of clean energy: What is the actual carbon footprint of aluminum-based hydrogen production? To find out, researchers conducted a life cycle assessment, tracking every step of the process—from sourcing aluminum to transporting the hydrogen once it’s produced.
They chose 1 kilogram of hydrogen as their benchmark, providing a real-world comparison for consumers. Why this amount? Because it’s enough to power a hydrogen fuel cell car for 60 to 100 kilometers, depending on efficiency.
They turned to Earthster, an advanced life cycle assessment tool that draws data from a vast repository of products and processes. They examined multiple scenarios, comparing hydrogen production using primary aluminum (mined from the Earth) versus secondary aluminum (recycled from products such as soda cans). They also factored in different transportation methods for both aluminum and hydrogen.
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After running extensive assessments, the team identified the lowest-emission scenario: a process that relies on recycled aluminum and seawater—an approach that not only slashes carbon emissions but also recovers gallium and indium, making it a cost-effective, self-sustaining system.
The results were striking. This method generates just 1.45 kg of CO₂ per kilogram of hydrogen, compared to conventional processes that emit 11 kg of CO₂ per kilogram of hydrogen. Moreover, the fuel’s cost—approximately $9 per kilogram—aligns with hydrogen generated by wind and solar technologies, making it a competitive and scalable alternative for green energy.
Researchers envision a commercial-scale hydrogen production system where scrap aluminum from recycling centers is shredded into pellets, treated with gallium-indium, and transported as solid fuel instead of volatile hydrogen gas.
At fuel stations near seawater sources, these pellets would be mixed with saltwater on demand, triggering a reaction to produce clean hydrogen, ready for consumers to pump into internal combustion engines or fuel cells.
But that’s not all. This process leaves behind boehmite, an aluminum-based byproduct used in the production of semiconductors and electronics. If recovered and sold to manufacturers, it could further reduce costs, making the system not only environmentally sustainable but also economically viable.
“The process works,” says Kombargi. “And we show that it can be environmentally sustainable.”
Journal Reference:
- Aly Kombargi, Brooke Bao, Enoch Ellis, Douglas Hart. Lifecycle assessment and cost analysis of hydrogen production via aluminum-seawater reactions. Cell Reports Sustainability. DOI: 10.1016/j.crsus.2025.100407
