Hydrogen fuel from scrap aluminum and seawater

June 06, 2025

Scientists in the US have used only seawater and recycled aluminum from soda cans to develop a groundbreaking method for producing hydrogen, which holds the potential to reduce the carbon footprint of the entire process significantly.

The new method reportedly emits merely 3.2 lbs (1.45 kilograms) of CO2 per kilogram of produced hydrogen, marking a nearly 90% reduction compared to conventional fossil-fuel-based methods.

Led by Aly Kombargi, PhD, a mechanical engineering expert who recently graduated from MIT, the research team evaluated the process in a comprehensive life cycle analysis and found it scalable, sustainable, and comparable to other green hydrogen technologies powered by solar and wind energy.

“We’re in the ballpark of green hydrogen,” Kombargi 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.”

Inside the new process

Even though hydrogen has long been considered a potential clean energy source since it emits no CO2 when used, most of it is still produced from fossil fuels. However, the current method releases up to 24 lbs (11 kilograms) of CO2 for every 2.2 lbs (one kilogram) of hydrogen generated.

Now, building on an earlier lab discovery by the MIT team, which showed that combining seawater, recycled soda cans, and a small amount of caffeine could produce hydrogen gas, the researchers turned to a much bigger question.

To answer whether the benchtop process can be scaled up to an industrial level, and at what environmental cost, the team carried out a so-called cradle-to-grave life cycle assessment, taking into account every step in the process at an industrial scale.

For the research, the team used Earthster, a comprehensive tool that tracks emissions at every step of a process. The analysis calculated 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.

A sustainable solution

According to the team, the most effective approach they identified involves using recycled aluminum, treated with a small quantity of gallium-indium alloy, which is then reacted with seawater.

The salt in the seawater supports the chemical reaction and helps precipitate the rare metals, which can be recovered and reused, making the process economically and environmentally circular.

“One of the main benefits of using aluminum is the energy density per unit volume,” Kombargi explained. “With a very small amount of aluminum fuel, you can conceivably supply much of the power for a hydrogen-fueled vehicle.”

The team estimated that the new process would cost about USD 9 per 2.2 lbs (one kilogram) of hydrogen compared to other green hydrogen technologies. Moreover, the reaction’s byproduct, boehmite, is a valuable material used in semiconductors and industrial products, which could help further offset costs.

“With a hydrogen fuel cell car using one kilogram of hydrogen, you can go between 60 and 100 kilometers [37 and 62 miles], depending on the efficiency of the fuel cell,” Kombargi stated in a press release. Instead of transporting volatile hydrogen directly, the researchers propose delivering aluminum pellets to fuel stations near seawater sources.

The pellets would then react with seawater on demand in compact reactors to generate hydrogen for vehicles, an approach which the team has already demonstrated with prototypes, including a reactor the size of a water bottle that successfully powered an electric bike for several hours.

“There are a lot of things to consider,” Kombargi concluded. “But the process works, which is the most exciting part. And we show that it can be environmentally sustainable.” The team now hopes to continue refining and scaling the process and to expand its applications to include underwater systems such as small boats and autonomous underwater vehicles.