Sweet-toothed bacteria confect hydrogen

Research funded by the

(EPSRC) has shown bacteria that can metabolise confectionery could be a valuable source of clean hydrogen energy in the future.

Bioscientists at the University of Birmingham have demonstrated in a feasibility study that these bacteria give off hydrogen gas as they consume high-sugar waste produced by the confectionery industry.

The hydrogen has been used to generate clean electricity via a fuel cell and has the potential to be used in hydrogen-fuelled road vehicles.

The successful laboratory demonstration produced hydrogen using confectionery waste as a feedstock. Birmingham-based international confectionery and beverage company Cadbury Schweppes, a partner in the initiative, supplied the waste. An economic assessment undertaken by another partner, C-Tech Innovation, showed that it should be practical to repeat the process on a larger scale.

As well as energy and environmental benefits, the technique could provide the confectionery industry, and potentially other foodstuff manufacturers, with a useful outlet for waste generated by their manufacturing processes. Much of this waste is currently disposed of in landfill sites.

In the study, diluted nougat and caramel waste was introduced into a 5-litre demonstration reactor. The bacteria, which the researchers had identified as potentially having the right sugar-consuming, hydrogen-generating properties, were then added.

The bacteria consumed the sugar, producing hydrogen and organic acids. A second type of bacteria was introduced into a second reactor to convert the organic acids into more hydrogen. The hydrogen produced was fed to a fuel cell, in which it was allowed to react with oxygen in the air to generate electricity. Carbon dioxide produced in the first reactor was captured and disposed of safely, preventing its release into the atmosphere.

Waste biomass left behind by the process was removed, coated with palladium and used as a catalyst in another project, funded by the Biotechnology and Biological Sciences Research Council (BBSRC), aimed at identifying ways of removing pollutants such as chromium (VI) and polychlorinated biphenyls (PCBs) from the environment. The reactors used by this parallel initiative also required hydrogen and this was supplied by the confectionery waste initiative too.

Professor Lynne Macaskie of the University of Birmingham’s School of Biosciences led the research team. “Hydrogen offers huge potential as a carbon-free energy carrier,” she said. “Although only at its initial stages, we’ve demonstrated a hydrogen-producing, waste-reducing technology that, for example, might be scaled-up in five to ten years’ time for industrial electricity generation and waste treatment processes.”

The team is now engaged in follow-up work which will produce a clearer picture of the overall potential for turning a wider range of high-sugar wastes into clean energy using the same basic technique.