Hydrogen is often touted as the fuel of the future, offering clean energy with water as the only byproduct. However, most current hydrogen production methods are expensive and emit large amounts of carbon dioxide—undermining its promise as a truly green fuel. Researchers at MIT may have found a way to change that, using a simple reaction between recycled aluminum and seawater to produce hydrogen cleanly and efficiently.
The technique, known as the aluminum-water reaction (AWR), utilizes scrap aluminum, waste heat, and a recyclable metal alloy to generate hydrogen with significantly lower emissions. A full life cycle analysis of this process revealed it produces just 1.45 kilograms of CO₂ per kilogram of hydrogen, compared to the 11 kilograms of CO₂ emitted by conventional fossil-fuel-based methods.
The method starts with treating recycled aluminum—such as soda cans or industrial scrap—with a small amount of gallium-indium alloy. This rare metal combination removes the aluminum’s natural oxide layer, allowing it to react with seawater. When the treated aluminum is mixed with seawater, a chemical reaction occurs that produces hydrogen gas on demand.
A key advantage of this process is that no desalination is required. Salt in the seawater actually aids the reaction and helps precipitate out the gallium and indium, which can then be recovered and reused. This creates a closed-loop system that minimizes waste and maximizes cost-efficiency.
To assess the true sustainability of the process, the MIT team conducted a full life cycle assessment using the Earthster platform, which evaluates carbon footprints across manufacturing, transport, and usage. The benchmark was set at 1 kilogram of hydrogen, roughly enough to power a fuel cell car for 60 to 100 kilometers.
They analyzed various scenarios, comparing hydrogen production using primary aluminum (mined) versus secondary aluminum (recycled), and considered different methods for transporting both raw materials and final hydrogen product. The lowest-emission scenario emerged from using recycled aluminum combined with seawater, making the process not only cleaner but also cheaper and more scalable.
The hydrogen produced through this method costs about $9 per kilogram, placing it on par with green hydrogen sourced from wind or solar power. However, this system brings the added benefit of energy storage and transportation in solid form, reducing the risks and costs associated with moving volatile hydrogen gas.
The researchers envision a future in which scrap aluminum is collected, pelletized, treated with gallium-indium, and transported as a solid fuel. At coastal fueling stations, these pellets could be mixed with seawater to generate hydrogen on-site, eliminating the need for hydrogen tanks or pipelines. This makes the system particularly well-suited for remote areas, island communities, or disaster relief zones.
In addition to hydrogen, the reaction leaves behind boehmite, an aluminum-based compound used in semiconductors and electronics manufacturing. If recovered and sold, this byproduct could offset costs even further and contribute to a more circular industrial ecosystem.
By reimagining waste as a resource, MIT’s aluminum-water hydrogen system not only offers a low-carbon energy solution but also opens the door to more sustainable infrastructure for fuel production and distribution. The approach is modular, scalable, and designed to make clean hydrogen available wherever recycled aluminum and seawater exist—turning yesterday’s waste into tomorrow’s clean energy.
By Impact Lab
