In 2000, the offshore wind industry was pioneering ways of installing 2MW turbines in water depths of just 15 meters, only a few miles off the coast. Today, 15 years later, a single turbine can produce a higher output than all the turbines combined in earlier wind farms, the blades are at least 4 times longer, the water depth can be over 10 times deeper and the sailing time from the coast can also be 10 times longer. Everything has become either bigger or longer or deeper!
To match this impressive development, the industry has sensibly focused on supply chain bottlenecks and improvement areas for cost reduction. Vessels, Ports, Access, Foundations, Turbines, Manpower and Financing are just some of the focus areas the industry has targeted during its remarkable development the last decade. All this has helped push the boundaries further out in the direction of what we believed was the way forward at the start of the millennium.
Going deeper than water depths of 15m or even trying to imagine an 8MW turbine being installed offshore was beyond the imagination of most people when the industry started. Now, the ability to install 80m blades on to rotor hubs well over 100m above in water depths greater than 40m has changed from science fiction to science fact. In fact, this work is already scheduled for the near future.
The industry has new installation vessels able to lift heavier loads higher. There are motion compensation platforms and attachments to the cranes that provide load stability from a vessel affected by the sea state. We have the ability to make the crane stable, but until now, the load suspended from the crane has always been exposed to the forces of the wind. This has been the cause of countless delays to installation and maintenance projects. But now, High Wind’s Boom Lock system changes all that. The innovative system enables the load to be stabilised while it hangs from the crane.
Offshore WIND talked to Johan Heiler, General Manager at High Wind about the Boom Lock system and the company’s experience at Kentish Flats Extension.
The first major hurdle Johan Heiler had to overcome was the industry’s perceived risk of trying new technology. Although the offshore wind industry has produced many innovative pieces of engineering in its short life, he feels that there is still a conservative reaction to new technology. But this barrier is slowly being removed. The appraisal of the work on the Kentish Flats Extension has proven that the High Wind Boom Lock does what it says on the label.
Johan Heiler explains: “Turbine blades are designed to catch the wind, and this is what happens when installing the blades onto the hub of the rotor on the nacelle, in anything other than wind still conditions. The Boom Lock stops the sideways movements of the crane block, and creates a fixed and unique rotation point for the hoisted load at the hook suspension. As a result, when the hook block is locked, the lifted load can only rotate around this point. As we then stop the load from rotating with our two sets of taglines, it becomes completely fixed even in windy conditions.”
Anything, either equipment or systems, that can reduce the down time caused by weather, can only benefit the industry, reducing the time vessels are waiting on weather, reducing costs. Safety is also improved by reducing the need for manual intervention when installing nacelles and the Boom Lock system makes the alignment of the turbine blade with the hub bolt holes a simpler task.
During trials conducted by High Wind, lifting was performed safely at wind speeds in excess of previous maximum safety limits. Johan Heiler says, “It was these trials that convinced Vattenfall and MHI Vestas to use the Boom Lock system at the Kentish Flats Extension project.”
The Boom Lock system is currently installed on the GeoSea jack-up Neptune, and High Wind is working closely with a number of vessel owners and turbine manufacturers to ensure lifting operations will no longer be the weakest link in Offshore Wind.
Dick Hill