Constructing turbines as tall as the Shard

22 August 2017

Declining government subsidies that underpinned the rapid growth of the renewable energy sector in recent years are causing leading wind energy companies, such as Dong Energy, EnBW and Vattenfall to pursue new revenue streams to pull back at their tightening margins. 

The wind energy industry needs to become more commercially viable in order to be able to compete with other energy sources and remain attractive to investors.

The prospective 10-megawatt 300 meter mega turbine proposes a monumental solution to this problem through a huge potential increase in production capability, but scaling up an established business model will always involve scaling up the risks associated with it. 

Michael Guldrandtsen, a leading offshore wind consultant for MAKE expressed deep concern in apprehension of his clients’ hugely increased financial and technical risks in speculating on the profitability of mega turbines when speaking to Reuters recently. However he also expressed an understanding of the requirement for wind companies to build these risk intensive structures in light of the government subsidy removal saying, “Without a significant increase in the size of turbines it would not be possible to ensure a reasonable return.”

The prototype mega turbine will have to be tested and run safely in an uninsured state for 8000 hours before it can reach the insurable status of ‘certified’. The risks will be highest in the prototype period and companies are looking to other industries, such as the aerospace market, for insight into how to mitigate risks such as the strain of turbulence from blades which could potentially be up to 50 metres longer than those currently in operation. 

Increased blade size also presents transportation to site challenges. If the routes utilised are not able to accommodate the increased blade sizes, they will have to be assembled on site. This could potentially increase the risks of damage as the construction of the blades is a complex, layered process. 

Manufacturers will need to adopt cutting edge blade technology in order to ensure that the slender and light blades of unprecedented size will not snap under the extreme pressure of gale force winds which will be needed to ensure that the turbines are able to rotate the large blades. This presents other risks as rotor blades tend to flex in high winds increasing the risk that the rotor could potentially hit the tower supporting them.

The increased and varied wind speeds experienced at the sites will increase the strain on the foundations. To avoid the risk of having to retrofit secondary foundations to mega turbine projects, developers should employ independent structural engineers to survey and ratify the project at every phase of its construction. 

The increased blade size could also result in increased noise from tower wake. However, the prospective sites for the initial mega turbines are thought to be far off-shore, reducing the potential for people to be disturbed but the distance from shore could make cost of repairing and maintaining the turbines prohibitively expensive.

Bigger rotors will result in fewer turbines and foundations needed to achieve the same capacity, increasing efficiency and reducing the cost of energy. It is this incentive which is fuelling the turbine makers and engineers to design the mega turbines of the future.  

To read further into methods of reducing risk exposure in wind energy download JLT Specialty and K2 Management’s report entitled, ‘Reducing The Levelised Cost Of Energy’.

For further information please contact Vanessa Anniss, Renewable Energy Team on +44 20 7558 3927 or email vanessa_anniss@jltgroup.com

contact Vanessa Anniss
Renewable Energy Partner, JLT Specialty vanessa_anniss@jltgroup.com