Flush of excitement at sewage fuel cell

Scientists have built a hydrogen fuel cell powered by sewage. The cell, the first of its kind, was used to transform sewage into useful hydrogen gas using the bacteria already contained in human waste.

The Newcastle University researchers have also demonstrated that sewage treatment plants have the power to run themselves while producing renewable energy. The findings were presented yesterday at the British Science Festival in Newcastle.

“It takes 0.5 kilowatt hours of electricity to treat every cubic metre of wastewater,” said Tom Curtis, professor of biological engineering at the University and lead researcher on the project with Northumbrian Water. “So we are taking an energy-rich resource and using a lot of energy to treat it . . . this is insane.”

"Pressure cooker"
The company and the researchers used a process they called "advanced anaerobic digestion", or AAD, which involves thermal treatment of the sludge followed by digestion using methane-making bacteria.

"We use a system much like a pressure cooker to break down the sludge and then feed it to bacteria to generate bio-methane," said Maxine Mayhew, commercial director for Northumbrian Water. "We have 17 Olympic-sized swimming pools of sewage each hour and can generate enough gas for 8,000 homes," she said. "Next, we'd like to send the biogas straight into the grid."

Investments
So far, the changes made at the treatment plants have involved investments of over €80 million.

The latest development in the partnership are hydrogen fuel cells. "Hydrogen is worth six times more than methane," said Prof Curtis.