Plastic turned into clean hydrogen fuel using solar reactor and waste battery acid

Researchers have developed a solar-powered reactor that transforms hard-to-recycle plastic waste into clean hydrogen fuel and valuable industrial chemicals.

The system, developed by a team at the University of Cambridge, uses acid recovered from discarded car batteries, offering a novel way to tackle multiple waste streams at once.

Powered entirely by sunlight, the approach could provide a cheaper and more sustainable alternative to conventional recycling methods.

According to researchers, the breakthrough highlights a potential circular solution where one form of waste helps process another.

Solar recycling innovation

Global plastic production exceeds 400 million tonnes annually, yet only about 18 percent is recycled, leaving the majority to be incinerated, landfilled, or released into natural ecosystems.

The newly developed approach, known as solar-powered acid photoreforming, offers a potential pathway to address this growing environmental challenge by converting plastic waste into useful outputs.

The system employs a specially engineered photocatalyst designed to withstand highly corrosive acidic conditions. This enables the use of acid recovered from spent car batteries, which is typically neutralized and discarded, turning it into a valuable resource within the recycling process.

In this method, waste plastics are first treated with the recovered acid, breaking down long polymer chains into smaller chemical components such as ethylene glycol. When exposed to sunlight, the photocatalyst then converts these intermediates into hydrogen fuel and acetic acid, a widely used industrial chemical.

By combining solar energy with waste-derived materials, the process presents a dual benefit—reducing plastic pollution while repurposing hazardous battery waste. The approach highlights the potential for integrated, circular systems where multiple waste streams are transformed into valuable products, offering a more sustainable alternative to conventional recycling techniques.

Clean fuel innovation

Laboratory tests show the reactor delivers high hydrogen yields while producing acetic acid with strong selectivity, and it operates for over 260 hours without performance loss.

The ream claims the process is effective across multiple plastic types, including difficult-to-recycle materials such as nylon and polyurethane, marking a significant advance over existing upcycling methods that are largely limited to PET.

A key advantage is its ability to use acid recovered from discarded car batteries rather than relying on newly produced chemicals. These batteries contain substantial volumes of acid that are typically neutralized after lead recovery, creating additional waste. By reusing this acid, the method turns a hazardous byproduct into a valuable input for plastic breakdown.

The system also offers the potential for major cost reductions compared to other photoreforming approaches, as the reusable acid boosts hydrogen production rates. While engineering challenges remain—particularly in designing reactors that can withstand corrosive conditions—the chemistry is robust. The approach is positioned as a complementary solution, targeting mixed or contaminated plastics that conventional recycling cannot process effectively.

“We’re not promising to fix the global plastics problem. But this shows how waste can become a resource. The fact that we can create value from plastic waste using sunlight and discarded battery acid makes this a really promising process,” said Erwin Reisner from Cambridge’s Yusuf Hamied Department of Chemistry, who led the research, in a statement.