Driving down the cost of offshore wind foundations

Andrew Thompson | 08 Sep 2014 | Comments

The UK’s offshore wind industry has a big target to hit of reducing costs by 30% by 2020, based on the delivery of 18GW of offshore wind. Atkins has been working with a number of the industry’s leading players to drive down the cost of offshore wind foundations.

The current major focus of almost everyone involved in the offshore wind industry is how to reduce cost. Driving down the cost of all parts of the sector can involve everything and anything from utilising bigger turbines, synergies in operations and maintenance, and taking a more standardised approach to the design of the structures themselves.

There is also a way in which to help reduce costs, before anything even goes in the ground, and that’s something that we at Atkins have been working on recently.

Burbo offshore wind farm
Burbo offshore wind farm

We’ve got over 40 years of experience in the oil and gas industry and during that time we have developed a lot of knowledge and expertise in how to engineer and design marine structures. The experience that our geoteam (made up of geologists, geophysicists and geotechnical engineers) has gained over the years is now paying huge returns as we look at how to optimise substructure design for the offshore wind industry.

Long before construction begins offshore, the developer has to undertake a series of investigations to find out where the best location of the wind turbine foundations will be, and to ensure that the foundations are designed properly for the ground that they are going in to. This is an important part of reducing overall costs of wind farm development – for example, it can take up to 14 hours and cost up to £75k to drill one borehole to 50m below the seabed, depending on the size of the vessel and specialist equipment needed.

State of the art geophysics and ground modelling software, originally developed in the oil and gas industry, is used by the team to help minimise the number of boreholes that are required. This is done by combining the geophysical and geotechnical data that is taken during the ground investigations at the site and is then used to build a reliable 3D ground model.

Shallow boreholes (to about 25 metres below the sea bed) can be done with smaller vessels and cheaper equipment, and take a much shorter time – for example, a 25 metre deep cone penetration test can be drilled in approximately four hours at a cost of around £10k, rather than £75k for a deep 50 metre borehole.

What this means is that the location of deep and shallow boreholes can be more selectively made, without compromising safety and the reliability of the information, as the offshore wind industry moves into deeper waters. This is one way of using tried and tested technology from the oil and gas industry to inform the cost reduction plans for offshore wind.

Our history of offshore experience is a huge benefit in how we work in renewables at Atkins. Whilst there are definitely significant differences between extracting hydrocarbons and harnessing wind power, there are also similarities and synergies that can be shared between one part of the energy sector and another.