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ENGINEERS at Leeds University, UK have developed a new self-heating process that they say could convert food waste into hydrogen gas.

Releasing the energy that is locked up in used vegetable oils thrown out by restaurants and fast food joints is no easy feat. Whereas simple molecules such as natural gas can be easily split into their constituent parts by mixing with steam and heating over a metal catalyst at temperatures above 800°C, oils are far harder to process. To convert oils to hydrogen at high volumes, more heat is required, otherwise the process is far slower and the resulting residues poison the catalyst and halt the reaction.

Valerie Dupont of Leeds’ engineering department believes she has overcome this problem by developing a two-stage self-heating process. A nickel catalyst is blasted with air to form nickel oxide, an exothermic reaction that raises the starting temperature from 650°C to 850°C degrees. The fuel and steam mixture then reacts with the hot nickel oxide to make hydrogen and carbon dioxide. The CO₂ is then captured by what the team describes as a ‘sorbent’ material leaving just the pure hydrogen.

“The hydrogen starts to be made almost straight away, you don't have to wait for all of the catalyst to be turned into pure nickel,” Dupont says. “So as well as the generation of heat, this is another way that makes the process very efficient.”

The process has been shown to work in a small test reactor and the team will now work to scale-up the operation in a bid to make more hydrogen over longer timescales.

“The beauty of this technology is that it can be operated at any scale. It is just as suitable for use at a filling station as at a small power plant,” Dupont says. “If we could create more of our electricity locally using hydrogen-powered fuel cells, then we could cut the amount of energy lost during transmission down power lines.”