“The reality is that the majority of downtime of turbine installation comes from wind speed limits for blade installation…So, we want to come to a solution that is less wind dependent and that’s difficult because blades are made to catch wind”, said Andries Hofman, Product Development Manager at GustoMSC, a NOV company, that is developing Wind Blade Installation (WBI) solution with the goal to improve the offshore wind turbine blade installation efficiency.
Hofman detailed on the solution at The Stage during Offshore Energy Exhibition & Conference in Amsterdam that took place on 29 and 30 November.
Called the Sjøhest, Norwegian for ‘seahorse’, the solution involves a new concept for blade installation equipment, either integrated on a dedicated newbuild NG-5500XL jack-up vessel, or as a retrofit on existing jack-ups.
GustoMSC says that the Sjøhest was developed in response to the installation challenges related to wind turbines now having higher towers accommodating larger blades.
To install these blades at heights reaching between 175 metres and to 200 metres, contractors encounter downtime as the wind makes the tower and blades sensitive to movements, obstructing safe installation and increasing installation time and downtime, according to the company.
“Currently, wind speed limits at the height part are well, let’s say somewhere between 12-13 metres per second. We’re aiming far above that, 17-18 metres per second. So, this is a step up”, said Andries Hofma.
With the Sjøhest WBI solution, the larger installation jack-up vessels equipped with heavy lift cranes install the towers and nacelles, while an add-on jack-up vessel equipped with a smaller handling crane and trolley with telescopic leader boom installs the blades that are placed on the vessel in a longitudinal way.
The Sjøhest comprises a trolley mounted onto a leader that connect to a wind turbine tower. A smaller handling crane picks up the blades from the rack and feeds the trolley.
“The gripping tool is moving together with the tower. This is called passive alignment. We don’t need heave compensation”, said Andries Hofman.
Once connected to the trolley, the blade is horizontally transported up along the leader, rotated into a vertical position, and connected to the rotor.
The bigger jack-up is still doing all the heavy lifting in the background while the smaller jack-up at a cheaper day rate tags along and installs the blades.
“In this way, we optimise wind turbine installation and the overall process of wind turbine installation becomes considerably faster mainly due to the lack of weather downtime”, added Hofman.
This is just a quick preview of one point that Hofman discussed on The Stage during Offshore Energy Exhibition & Conference. To access more, go to OEEC On Demand: