The power of poo
By Kirsty MacLeod
Few of us think twice about what we flush down our toilets. For some, however, it’s a source of infinitely renewable energy that could power our future sewage plants, and more. Speaking at the British Science Festival today, experts from Northumbrian Water and Newcastle University spoke of their shared commitment to harnessing the energy inherent in our waste – literally, the power of poo.
“It takes a lot of energy to treat a metre cubed of waste water,” explains Professor Tom Curtis, Professor of Biological Engineering at Newcastle University. “But that waste water contains even more energy than it takes to treat it!”
Curtis and colleagues are currently working with Northumbrian Water to find the best and most efficient way of extracting that energy to make the water treatment process a sustainable, even profitable venture. Currently, they are trialling a hydrogen Microbial Electrolysis Cell (MEC), a fuel cell that produces hydrogen gas from raw sewage. This hydrogen gas is a valuable fuel, worth about six times as much as methane, the main gas produced by older methods of sewage treatment.
“Northumbrian Water is industry leading in terms of this kind of sustainable power,” says Commercial Director Dr Maxine Mayhew. With 2.6 million customers, and 400 water treatment plants, the process of treating waste water results in a massive 1.6 million tons of sludge per year. Fifteen years ago, that would have been dumped at sea. With the sense that they were, literally, wasting their waste, Northumbrian Water began to use treatment methods that produced gas from their sludge, that in turn could produce power. By doing this, they became the first waste water company in the UK to make use of all the sludge produced by their plants to generate energy.
Now, their aim is to make this energy production even more efficient. The UK uses about 2% of its energy treating waste water, says Curtis, a percentage of our energy bill that could be eliminated by using Microbial Electrolysis Cells. Mayhew believes that by 2015, a fifth of all power used at Northumbrian Water will be from biological sources – and further in the future, they could power themselves completely.
From an academic point of view, Curtis is blunt about the rate at which such renewable energy-producing systems are being developed, relative to the need for sustainable energy.
“If we go at the rate of one PhD at a time, it will take twenty or thirty years to see this kind of energy production implemented in the UK,” he says. “We just don’t have twenty or thirty years!”
The need to increase the rate of innovation, he says, necessitates a trial-and-error approach that diverges slightly from his academic background. “Academics strive for perfection,” he says with a smile. “We’re trying to get away from that.”