Bacteria grown for gas generation

Future demand for hydrogen could be met by producing it from bacteria grown in biomass, say technologists at Belgian research organisation VITO.

Karolien Vanbroekhoven, programme manager of separation and conversion technologies at VITO in Boeretang, said other groups around the world are looking into hydrogen production out of biomass, but her team’s work is unique because it focuses on dark fermentation, a process that does not use light as an energy source.

The fermentation process requires solid organic waste enriched with wastewater. The organic compounds of this biomass act as a carbon source for bacterial growth and a source of energy for their metabolism.

’Since they do not require light energy, they can constantly produce hydrogen from organic compounds throughout the day and night,’ said Vanbroekhoven.

The organic biomass is fed into a bioreactor, similar to an anaerobic digester, but specially designed for removing hydrogen.

’If hydrogen is not removed efficiently and fast from the reactor, the process stops,’ she added. ’Typically, both a mixture of at least hydrogen and carbon dioxide are produced and removed by stripping and combining with gas separation membranes.’

However, research and development still needs to be carried out in this area.

Vanbroekhoven envisions hydrogen produced in this way being used for either fuel-cell applications or as a chemical. The key will be in scaling the technology to an industrial level.

’If it’s used as chemical, more compression is needed, and that again increases the investment and cost of production,’ she said.

Vanbroekhoven’s team is continuing to work on increasing efficiency of its process and hopes to have a commercial plan soon.