Concrete Contender for Most Cost-effective Foundations for Offshore Wind Turbines
With the Government’s first agreements under the Contracts for Difference (CfD) Scheme awarded and the latest report from MEC Intelligence, yet again demonstrating superior cost and engineering performance - the forecast is set fair for concrete gravity bases.
Based on an auction process, The Department of Energy & Climate Change (DECC) has recently awarded contracts for two offshore wind developments and both have the potential to use concrete gravity bases.
Concrete gravity bases offer a reliable solution to developers because of the inherent strength that they possess, this is vital in depths of 25 m to 60 m and up to 200 km from shore. Moreover, in terms of the immediate requirements from authorities and developers alike, the high damping properties of concrete minimises noise and vibration.
The avoidance of piling noise during installation is a major benefit of concrete gravity bases as the impact on wildlife from piling noise is minimal.
With monopiles already ruled out for both CfD sites, East Anglia 1 and Neart na Gaoithe, due to the issues of underwater noise and the performance limitations in deeper water; both the projects’ requirements, at 30-41 m and 40-60 m water depth respectively, can be met by gravity bases.
Modules would be built on land prior to taking out to sea and placing in position.
Engineering performance is not the only project driver. Environmental and economic considerations are also a priority.
Concrete bases are installed using gravity and consequently the impact on native sea-life is low, especially in comparison to other options.
As well as the carbon savings related to the energy production, concrete gravity bases also have lower embodied carbon than many steel alternatives.
When considering economic benefit of foundation solutions, the performance of concrete gravity bases is also superior.
A recent study by MEC Intelligence compared the cost of a monopiles and jackets with gravity bases and suction buckets. The costs assumptions are based on actual values witnessed on projects and from inputs from industry experts.