A wind turbine nacelle houses the key components of the wind turbine including the gearbox and the electrical generator. It is like a 2-storey house sitting on top of a 20-storey tower. Currently, assembly, maintenance and replacement of parts is time-consuming, expensive and disruptive. The EU-funded Liftra Crane project coordinated by Liftra has delivered an elegantly simple universal solution for turbines of all makes around the world. A small self-hoisting crane (SHC) promises to significantly reduce the lifecycle cost of wind energy, enhancing uptake.
Bigger is not always better
As wind energy technology has continued to evolve, wind turbines have grown from an average turbine height of 32 metres in the early 1990s to 101 metres tall on new wind farms commissioned. Cranes to service the turbines had to grow in order to reach them. Transporting and installing large cranes requires large trucks and about 10-20 truckloads, often necessitating changes to roads and bridges, clearing of land at the base of the tower, and significant assembly and maintenance time. Delays in finding an available crane add additional downtime and cost. Thanks to Liftra’s SHC, large cranes are no longer an issue. According to Thomas Lamberth Sandbjerg, Head of Communications at Liftra, “The system is transported in a standard 40-foot container by a single truck. The first-generation SHC can climb up to 145 metres using its wire system. Finally, it can operate in wind speeds up to 18 m/s compared to around 9-11 m/s, decreasing delays caused by high winds.” Realising the SHC could also be used to change the large turbine blades, Liftra developed a lightweight blade yoke called the ‘Blade Skylark’. It can be lifted by the SHC from atop the turbine. The yoke clamps the blade and pivots it from vertical to horizontal as it lowers the blade to the ground.
The winds of change are strong
As Sandbjerg explains, “The key achievement has been the development of a universal, brand-independent system that has secured third-party approval for use in all major wind turbine markets: Canada, China, Europe, India, Mexico, and the United States (USA). This verification covers both the choice of design standards in each market and the final crane design in accordance with these standards.” In the USA, use of the SHC has already begun to compete as a mainstream method for changing gearboxes. Around 10 SHCs have been purchased in North America. Customers operate the cranes independently and the total number of gearbox changes is approaching 500. “The SHC is a miniature crane that can perform the same job from atop the turbine as a large 100-metre high crane assembled next to the turbine. Maintaining wind turbines at a lower overall cost with much less environmental impact reinforces wind energy as a competitive alternative to fossil fuels,” Sandbjerg summarises. This is a win-win situation for companies and the planet.
Liftra Crane, crane, wind, turbine, self-hoisting crane (SHC), energy, blade, height, maintenance, cost, nacelle