Moving giant blades of glory

New onshore wind projects, such as Chleansaid in the Scottish Highlands, will feature just 16 ‘super’ turbines, with a maximum tip height of 200 metres and will power an estimated 54,000 homes.

The sheer size of the indivisible turbine blades and other components, including the turbine tower sections, and the fact that many windfarms are located in remote and inaccessible areas, creates significant challenges for developers transporting these components to site.

The blades cannot be folded or bent once constructed, placing severe limits on the routes turbine delivery vehicles can take in reaching their end destination. Nor can large turbines be transported over the airspace of private properties to a windfarm site without securing overrun and oversail rights from the appropriate landowners.

This can add significant time and cost to a windfarm project as well as potential environmental impact if it is necessary to carry out civil engineering works to widen existing roads and remove street furniture to facilitate the transport of larger turbine components.

Some private landowners might not be willing or able to grant overrun and oversail rights to a windfarm developer, while others may already have granted exclusive rights to another developer. In such cases, the existing agreement would need to be unpicked before further rights can be granted.

In cases where landowners are unwilling or unable to grant the access rights required, developers can invest in blade lifting technology. The blade is tilted during transportation in order to avoid overrun and oversail issues. While this new technology is starting to be used in Scotland, it is not yet commonplace as it requires specialist vehicles which are not readily available and which are significantly more costly to run than standard turbine delivery vehicles. The use of specialist blade lifter vehicles is also not always practical due to speed and wind restrictions when the blades are tilted.

Developers can also consider using split blades in order to avoid overrun and oversail issues as they are transported in smaller sections and assembled on site.

Given this potential web of issues, we are now seeing the use of compulsory purchase order (CPO) rights, available to developers holding a generation licence under the Electricity Act 1989, to help enable the delivery of key infrastructure to windfarm sites.

While these powers are commonly used for cable route rights, the use of CPOs to minimise the risk of voluntary deals for overrun and oversail rights not being achieved is new.

A CPO was submitted to the Energy Consents Unit by SSE Generation in December 2023 for the Strathy South Wind Farm transport route. In what we believe to be the first CPO of its kind, we await the decision on whether it will be granted.

Two years down the line from this CPO submission, the majority of overrun and oversail plots along the transport route have been withdrawn from the CPO, so it has done its job in terms of incentivising landowners to agree voluntary land deals.

The Scottish Government is also consulting on reforms to CPO and specifically asking for input on granting powers to acquiring authorities to create new rights in land and to attach conditions to such rights.

As onshore windfarm developments with increasingly larger turbines continue at pace across Scotland, CPOs could play an enhanced role in helping developers secure access to their sites.

Claire Wallis is a Partner at CMS