Up to £1m may have to be spent on upgrading the airport’s radar system if a windfarm development in the south of the island goes ahead.

Manx Utilities says until a manufacturer is appointed it can’t confirm the exact cost of the windfarm proposed for Earystane and Scard - but it’s current working assumption is £36m including contingency margins.

A breakdown of estimated costs has been released in response to a Freedom of Information request.

It includes a contingency of £1m for a radar upgrade at the airport, and an alternative of between £80,000 and £120,000 spent to ‘revise airport procedures’.

The estimates also include £1.54m on constructing a 7.7km underground connection to the electricity grid.

There is a further £250,000 for offsite road improvements, on-site tracks and on-site electrical infrastructure - these costs based on a five turbine layout, but will be lower if there are four.

The cost estimates also include £6.1m ‘manufacturing capacity booking’ (based on 25% of the estimated manufacturing cost) and a £1m contractor booking. These payments are listed to be paid this year.

Manx Utilities will not be submitting its planning application for the Earystane windfarm until early 2025.

The FoI request had asked why costs had risen from £23.5m outlined in the original site selection report to the estimated figure of £36m given today.

Manx Utilities in its response said the initial feasibility studies cited a 21 megawatt design but following further surveys the current range of turbine designs being considered is 20-28MW. A spokesman for Manx Utilities said: ‘Manx Utilities have attempted to be as open and informative about the outturn costs of this project and as helpful to the public and interested parties as possible.

‘At this stage we do not have a final design and therefore it is not possible to be too specific about outturn costs.

‘We do anticipate these to be within the £36m cost envelope, but this is still subject to verification through tender. We have sensibly included some contingency funding within the £36m evaluation.

‘When we formally engage with the supply market for the wind turbines themselves and the activities needed to construct them, we will be able to properly include their programme details into ours.  We will of course be taking steps to minimise the commercial risks as much as possible.

‘We are also working with our specialist consultants to establish an indicative design which will help inform our negotiations and subsequent planning application.  All of the work to date validates the choice of site and the anticipated benefits of constructing a windfarm at Earystane.’

She added: ‘With respect to the airport’s radar system, due account has to be taken into how the wind turbines will be perceived by the system i.e. they should not be confused with genuine aircraft. 

‘This is true for both on-shore and off-shore installations.

‘Modern radar systems can be “tuned” to take account of known turbines. 

‘We understand that the current system does not have this feature hence we’ve built some contingency into our project costs although, we anticipate that these costs would be shared with other developers of a similar nature.’

The original site selection document said Earystane was limited to five 4.2MW turbines without the construction of a beach access ramp being built at Castletown.

But that beach landing option has since been ruled out, with the turbines now to be shipped to Douglas harbour and transported by road.

The FoI response shows that the beach landing option would have cost an estimated £2.14m - £1.7m for shipping and delivery, £100,000 for ‘facilitation works’ and £340,000 on contingencies and other miscellaneous spending.

Delivery via Douglas is costed at an estimated £1.15m.

Arbory, Castletown and Malew MHK Jason Moorhouse has tabled a question on the windfarm costs at this week’s House of Keys sitting.