Uphill climb for gravity bases

A new study by Carbon Trust has outlined the barriers that exist which are stopping the increased use of gravity base structures as foundations at deep water offshore wind sites.

The study, supported by the Scottish Government, found that GBS’s are currently deployed for shallow water wind projects but as developers have ventured further offshore into deeper waters they have not been used for large scale commercial projects.

The study states this is due to a lack of confidence in the fabrication and installation of the structures for commercial projects, adding that further investment in fabrication infrastructure is needed to change this. 

It states that the infrastructure and supply chain for steel foundations that already exists is not there for gravity based structures which need specialised concrete fabrication sites, ideally close to deployment sites.

The report also found there has been a “lack of will” from the supply chain to invest in big production sites and that the slow uptake will “continue unless industry confidence increases and investment into building the right infrastructure can be minimised.”

Carbon Trust offshore wind manager Marc Costa-Ros said: “Gravity base structures offer the offshore wind sector a cost effective foundation solution of offshore wind farms in deeper waters.

“They also have the potential to be less affected by external load forces due to the more rigid nature of concrete over steel. To encourage development at the scale required to meet the level of industry demand, new specialised fabrication sites must be built.

“We have now reached a ‘chicken and egg’ situation and open dialogue and collaboration between designers, developers and other industry stakeholders will be critical to realising the full potential that GSBs offer to the sector.”

The report concludes that more work needs to be done to show that gravity based structures work at deep water sites with larger turbines and offers recommendations for designers, developers and governments on how to increase market share for GBS.

 Image: Sxc