Is it really possible to generate extra energy by embedding piezoelectric devices in train track sleepers?
Greenrail is a company that claims to produce "green" railway sleepers. They are partly made of recycled material, which is ok I guess. However, additionally they claim that their sleepers generate energy by converting the weight of passing trains into electricy. This supposedly works by adding piezoelectric devices in the sleepers under the tracks. They mention values of 1.25 MWh per 100 km track for 10-20 passing trains.
Is this really possible, or will the extra energy just come from the train which has to use more gas or electricity to keep moving? In other discussions some people claim the energy would otherwise be lost by heating and deforming the tracks or gravel bed.
Posted Mar 31, 2015, 12:18 PM UTC
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The energy they're capturing is the deformation of the tracks as the trains drive over them. If the tracks deform the same amount as they would before (or less), then it is energy that would otherwise have been wasted as heat and mechanical deformation of the track/bed. If the track deform more due to the presence of these devices, then the trains will have to use more energy to drive along it (constantly rolling 'up' the slope of the deformation), and this extra spent energy will be the source of the output power.
So the question is if it's possible that the track deforms only the same amount with a piezoelectric device which presumably has to be pushed down.