An entire fleet of around 100 'urban' wind turbines has been remotely shut down by manufacturer Quiet Revolution after the discovery of a design fault.
The fleet of QR5 turbines was disabled after continual wind speeds of between 14 and 24 metres per second caused a turbine located on a sea wall in Blackpool to develop a mechanical error, the company said in a statement on Friday. The QR5s have been installed on 55 sites for clients including Network Rail, Sainsbury's and self-storage firm Big Yellow.
Jim Campion, chief executive of Quiet Revolution, said the suspension of the fleet was a safety precaution.
"We detected a fault, but we couldn't determine the cause, so we suspended all of the turbines," said Campion on Monday. "We've only seen the problem with the seal on one turbine, but it could happen to others, and if there's any risk, we need to restart the machines."
Quiet Revolution said the fault allowed one of the turbine blades to start to separate from the central spoke, causing the spinning rotor to become off-balance. The initial blade slippage was caused by a corroded pin, which in turn was caused after water entered the mechanism through a badly fitted seal.
The company's ability to monitor its fleet meant the safety system detected the fault and shut down the damaged turbine immediately. The turbine safety system then informed Quiet Revolution's operations team of the turbine shutdown.
Each £38,000 turbine was checked by three teams of technicians and turned back on if they showed no sign of the defect. So far, 39 of the turbines have been inspected, and 32 are now operational. The remaining turbines are dormant because they show early signs of the fault.
According to Campion, the seal has now been redesigned and fitted to a prototype, which the company hopes it can install to every turbine before Christmas.
A report for Southwark Council, which is considering installing Quiet Revolution's urban turbines as part of its Elephant and Castle regeneration project, found the QR5s could consume more energy than they generated. The report, which was undertaken by the Gas Dynamics consultancy and released on Friday, also said the control system often cut out when large gusts of wind triggered its vibration sensor.
According to Tony Moseley, assistant director of infrastructure and sustainability at Southwark, the fault with the vibration sensor has been corrected, but the council is unlikely to install the turbines.
"At Elephant and Castle there are usually low wind speeds, and the turbines use more energy to spin when the wind is low, so it's not sensible to install them, in my view," said Moseley on Friday. "If wind turbines are going to be used in more urban areas, the industry needs to create turbines to harness low winds."