Electricty generating speed bumps

Due to today's lack of major stories relating to the renewable energy sector in the UK I thought I would give my opinion on a story I read in the Guardian last weekend. This article dealt with a new idea to generate electricity using the kinetic energy in traffic by utilising updated speed bumps. This seems like a very good idea on the face of it.


However, one has to question where these will be sited. It is a fact of physics that energy cannot be created or destroyed, and so the energy from the electricity will have to come from the vehicles passing over the new devices. As such the vehicle will lose energy (presumably in the form of speed) whilst it travels over the speed bump, and so if the driver wishes to maintain the speed it will need to increase fuel consumption. As a result there is the potential that siting these will result in increased fuel usage in the vehicles to allow the electricity to be generated. It would also be the case that this would be a very inefficient way of generating electricity, since the internal combustion engine in the vehicle is less efficient than even fuel oil fed conventional power stations, and on top of this there are the inefficiencies in associated within the speed bump.

I do appreciate however that since the idea of a speed bump is to slow the traffic down this could be a good thing, especially if the bumps were tuned so that they only took energy out of the traffic when it was above a certain speed. In these cases it would be good, and for this reason i could see these being particularly useful in areas where braking is happening, such as at the bottom of long hills and also on stretches of roads where it can be determined the drivers will slow down after the speed bumps.