Researchers from Spain and the UK have used computer modelling to show for the first time that hanging wind turbines below tall bridges can be a viable way to harvest sustainable electricity.
Just one installation would be capable of generating around half a megawatt of electricity, enough to power around 450 to 500 homes.
“This kind of installation would avoid the emission of 140 tonnes of CO2 per year, an amount that represents the depuration effect of about 7,200 trees,” said Oscar Soto, a researcher on the project from Kingston University in London, told Spanish publication SINC.
The team modelled the efficiency of different wind turbine options hanging from a viaduct bridge – a bridge that crosses only land, not water – in the Canary Islands. The Canary Islands are a perfect theoretical testing ground for this type of technology as they’ve already invested heavily in renewable energy.
One of the Canary Islands, El Hierro, with a population of around 10,000, became the first island in the world to be powered entirely by wind and water.
The computer simulations showed that turbines hanging off the Juncal viaduct on Gran Canaria Island could definitely contribute to their electricity generation without taking up any precious space on the island.
The simulations found that multiple small turbines generate more electricity than large ones, and found the best set-up to be 24 small turbines stationed under the Juncal viaduct. “The bigger the rotor surface, the more power can be extracted,” said Soto.
However, the complexity of such an installation increases the difficulty and the cost. Taking cost and difficulty into consideration, the most efficient structure involves just 2 identically sized turbines capable of generating a quarter of a megawatt each, as shown in the artist’s recreation.
The results have been published in Renewable and Sustainable Energy Reviews.