A MASSIVE wind farm off the coast of Wirral was out of action for four weeks after a problem with onshore cabling, the Globe can reveal.

A joint in an underground cable connecting to the Burbo Bank farm “failed” and it took engineers four weeks to first locate the breach, excavate down to it and then carry out repairs.

Globe reader Colette Dunkley contacted the Danish wind farm owners, Dong Energy, after noticing that all 25 of the giant turbines in the Burbo Bank Wind Farm had been still for some time.

Colette, a science teacher, wrote: "I regularly walk along the Wirral foreshore and cannot help but notice that the turbines on Burbo Bank are motionless regardless of the wind speed.

"In fact they only seem to move, if at all, in light airs.

"I am a supporter of alternative energy despite the fact the turbines intrude on a much-loved seascape.

"However if we have to have them on Burbo Bank I want to see them harvesting the abundant kinetic energy of the wind that we have here."

She added: "The West Hoyle and the Peel Holdings turbines always seem to be in motion.

"It almost looks as if there is some design fault as the turbines do not tack into the wind like the dock board turbines.

"As a tax payer and concerned citizen I would like to know why they do not function?"

A Dong site manager later replied to Colette confirming that the wind farm had been out action.

"We are currently experiencing a total loss of electrical supply to and from the National Grid due to a failure of a 132KV onshore underground cable owned by Scottish Power," he said.

The manager explained that it was the cable connecting the wind farm to the National Grid via a Wallasey substation.

"It is therefore beyond our control and we are waiting for Scottish Power to repair the cable.

"This has been very frustrating for us because up to the cable failure the wind farm has been operating very reliably with an availability of over 97%.

"Please be assured that there our Siemens turbines do not have a design fault and are the latest in offshore wind turbine technology."

Asked how much electricity had been lost during the four-week lack of operations, a Dong spokesman said: "We are not able to say, since it depends on how much wind there was at all time in the period.

"But the four weeks were overall a low production period with only three days of good winds."

Repair work on the failed cabling joint was completed last week and, after a day “energising” the turbines, the wind farm became operational again last Monday.

An SP Manweb spokesman said: "A rare fault occurred on the underground power cable that connects Burbo Bank windfarm to the electricity grid.

"Following a detailed investigation and sensitive excavation, engineers identified a specific section of cable that required repairs.

"This work has now been completed and the cable is back in service."

FACT FILE:

The Burbo Bank Offshore Wind Farm comprises 25 efficient wind turbines and is situated on the Burbo Flats in Liverpool Bay at the entrance to the River Mersey, approximately 4.5 miles from north Wirral and 4 miles from Sefton.

Burbo Bank is exposed to the full force of the wind from west. The Irish Sea and its shifting sands were once feared by storm driven sailing ships. Dong says these same winds and shallow waters now make it an ideal location for offshore wind turbines.

The location was chosen for a number of reasons:

Good average wind speed

Shallow water depth

No perceived environmental issues

Good seabed conditions for foundations.

Close to an onshore electricity connection

Within Port Authority jurisdiction (for safety reasons)

Local familiarity with wind power - Seaforth Docks Wind Farm

Each wind turbine is designed to run for approximately 6000 hours each year over 20 years.

By comparison, the design life time of a car engine is 20 times less - ie only one year if the car is set to run 4,000 to 6,000 hours.

The windfarm is comprised of:

Turbines.

Foundations of the monopile type.

Array cabling that connects the turbines to an export cable.

Export cable which transmits the power to an onshore substation.

Onshore substation which steps up the voltage before feeding the power to the main national grid.