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Can your toilet generate electricity?

man's hand on a toilet flush handle

Turning toilets green

The amount of water flushed down our toilets is considerable – in fact, it’s the second biggest use of water in the home behind showering.

There must be a way to harness all this moving water, right? Well actually, the technology does seem to be there to turn toilets into a kind of home hydropower system.

Will toilet tech bring electricity-generating flushes?

Back in 2014, research was published on a device using a transducer to convert the motion of water into electrical energy – with its suggested application in ‘home water flushing’ particularly capturing the imagination.

So, will we soon be charging up our smartphones or even doing a wash on the electricity generated by the day’s toilet flushes? Not quite. At that point, proof of concept was based on the ability of water movement to light an LED, and the researchers did point out that this was technology in its infancy, with potential gains dependent on factors like flow speed and the structure of the device. Unfortunately, infancy hasn’t turned to technological maturity yet, as there clearly remain a distinct lack of power outlets on our cisterns.

It’s not the only flush power technology that has been mooted, though. There’s also the Benkatina turbine, a hydroelectric turbine made to fit inside pipes and deals with variable water flow. Sounds promising in pursuit of powering up those WCs, but unfortunately here again, there hasn’t been much public progress with the technology since five or so years ago.

Super sewage offers other green options

We’re yet to see early progress in this area turn to toilet flush hydropower becoming the norm – but there are plenty of examples where the potential of human waste as an energy source is being tapped. The authorities of Portland, Oregon are selling sewage effluent as a viable fuel, while in Colorado, eight million tonnes of human waste is being converted into biomethane to be used in vehicles such as buses.

Closer to home, Yorkshire Water’s multi-million pound commitment to ‘poo power’ continues apace with the construction of a device to store gas from sludge treatment, which should in turn provide for over 50% of a water treatment plant’s energy needs.

It is these sorts of bog-based innovations which seem to be the more likely, or at least immediate, ways we’re going to see more being done with our bodily wastes. There seems to be growing industry appetite to take on this challenge, with the global lead for water and wastewater at energy efficiency technology company Danfoss recently highlighting the potential in every flush. It was stressed that optimisation of water treatment facilities can aid the recovery of biogas from sludge, which can in turn lead to situations where water treatment in localities or even cities produces an energy surplus.

Water way to waste

Whether flushing turns to electricity available right there in our homes remains to be seen, but there’s certainly room for improvement in terms of the water efficiency of flush mechanisms. A recent research paper evaluated two novel flushes: one featuring a rotatable blade in the bottom of the bowl, and other a rotatable trap system which uses gravity to aid the discharge of waste and so reduce the amount of water required to help it on its way.

According to the researcher, the second is a more viable option right now, and can involve less than one litre of water in the flush process. The other, it seems, needs a bit more work to get right.

The combination of water efficiency, waste management and energy generation makes toilets a perhaps surprisingly appealing place to explore in making our homes and their resource consumption more sustainable. Conscious flushing, in whatever form that takes, seems to be the future.

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Gary Hartley's picture
Gary Hartley is Energy Saving Trust's expert blogger. He has extensive experience researching and writing on a number of topics, with particular expertise in sustainable energy, policy, literature and sport. As well as providing regular blog content, Gary has also been published in numerous magazines and journals.