The concept was unveiled by the Danish wind OEM in April, in what it said was a bid to test the rule that turbines must always increase in scale to boost their power output.

The demonstrator turbine is undergoing trials at Denmark’s Risø test site in co-operation with the Technical University of Denmark.

The machine under trial has a tip-height of 74-metres and uses four refurbished V29-225kW nacelles. It includes a host of sensors to measure and test performance, including a Lidar system mounted atop the support structure to monitor wind fields.