Placing wind turbines in 'dead space', such as underneath bridges, is a strategy that's often been suggested, but no one's ever tested how efficient it could be. Now researchers in the UK have used computer modelling to show for the first time that not only would wind turbines hanging below tall bridges be a viable way to harvest sustainable electricity, but that one of these installations would be capable of generating around half a megawatt of electricity, or enough to power around 450 to 500 homes.
So what type of turbines should we be attached to our bridges? The researchers compared fluid dynamic simulations and found that multiple small turbines generate more electricity than large ones, and the best set-up in terms of energy harvesting would be 24 small turbines stationed under the Juncal viaduct. The bigger the rotor surface, the more power can be extracted.
But when you factor in the cost and difficulty of installing all of these small turbines, the benefits are actually cancelled out. In the end, the most efficient structure involves two identically sized turbines capable of generating a quarter of a megawatt each.