Silent revolution

Cities can be windy places, especially in the UK, but urban wind turbines are a rare sight. The architects behind the London Eye are trying to change that with an ambitious plan to install 6,600 wind turbines in London in time for the 2012 Olympics, boosting the city’s green credentials. But these turbines won’t be the familiar triple-bladed units; they’ll be unlike anything the city’s ever seen.

David Marks and Julia Barfield, the celebrated husband and wife architectural team, have come up with the Beacon, an array of five, vertical-axis wind turbines set in a Y-shaped structure, specifically designed to generate the maximum power from the awkward wind conditions that occur in cities. ‘We live in one of the windiest countries in the world,’ David Marks said. ‘There’s no shortage of it anywhere.’ However, exploiting it is not simple, he said.

Although we are used to seeing power stations on the fringes of urban centres, or on the coast, there is a logic to generating power within the city.

‘The Victorians got it right when they decided to build their power plants in the centre of cities, because that’s where the power is required,’ Marks said. ‘They only moved them out of the city because it’s a dirty technology. But wind really is clean and city centre turbines would avoid the fantastic losses in energy production and transmission that you get with remote generation.’

There are two problems with urban wind generation, one linked to the nature of the wind and the other with the nature of cities. Average windspeeds in urban environments tend to be low, with occasional gusts of very high wind; the wind is also turbulent, with rapid changes of direction. This means conventional, horizontal-axis turbines are inefficient. They can only generate power when facing into the wind and, while they are tracking to take up the optimum orientation, they are not generating.

The second problem is that the noise and vibration generated by wind turbines is not acceptable in cities; it would disturb the large numbers of people who live and work nearby and the vibration could damage buildings and infrastructure.

The Beacon design avoids these problems because of the turbines it uses. The QuietRevolution turbine, developed by engineering consultancy XCO2, is a triple-bladed, vertical-axis turbine that is claimed to be silent and vibration-free.