Warning: “Hype round energy harvesting may seriously damage our credibility”

I saw a news report recently where a hotel was offering a free meal for guests that were willing to get on an exercise bike equipped with a dynamo and contribute to the hotels power supply. Now as way of raising energy awareness it’s great, but as a practical solution it fails. Olympic cyclist Chris Hoy, with thighs like tree trunks might be able to generate enough power to fry his steak, but I’m afraid the rest of us would have to order the Gazpacho.

There is a danger that these stories are creeping into the energy harvesting field, potentially diluting all the good work. We’ve all heard about the club dance floor where they have piezoelectrics in the floor and generate power for the lights haven’t we. Or is that an urban myth? If that was really such a good idea, wouldn’t we know someone that had been, and said how fantastic it was, or there would be one locally?

A few weeks ago I had a call from a shower manufacturer that had heard about piezoelectric fibres and how they could be used to heat the water for a shower. The idea was that piezoelectric fibres inside the water pipe would vibrate with the water flow and generate enough electrical energy to power a water heater. Conceptually it doesn’t sound that mad, but the numbers just don’t add up. I could count the number of piezoelectric energy harvesters that generate one Watt or more on the fingers of no hands, whilst if you’ve ever looked at the fuse board where your electric shower is wired, you’ll know these are rated in kilowatts. I’m afraid we’ll end up having a cold shower, figuratively and literally!

How do we stop people getting carried away with these stories? If there are too many of these ideas where there is never any delivery of an end product, people will tire of the idea, and it will be seen as another cold fusion. Whenever we hear an idea about a wild and wacky energy harvesting concept we should give it a severe health warning, or better still pass on a more positive story.

I heard about an oil refinery where they attached sensors to all the pumps in the plant. The pump vibration was enough to power the sensor and to send a wireless signal reporting the state of the pump. The company can now plan preventative maintenance before any catastrophic failure of the pump occurs. That’s a real energy harvesting success story – and one we should be telling.