Interview by Rikki Stancich

Assessment and certification heavyweight, Bureau Veritas, has issued the world’s first ever set of guidelines for the classification and certification of offshore floating wind turbines.

The guidelines, which cover floating platforms supporting both single and multiple-turbines with horizontal or vertical axes, have been issued in response to growing demand for deepwater offshore turbine installations. 

Wind Energy Update speaks to Maxime Pachot, Offshore Wind Turbine Manager, Bureau Veritas, who authored the guidelines, to how they will impact the industry going forward.

Wind Energy Update: The three types of floating turbine include Ballast floating platforms, Tension Leg Platforms (TLP), and Buoyancy floating platforms. What are the key criteria for each of these FTPs?

Maxime Pachot: In terms of the parameters for each, these have yet to be determined. The key point is that we are not focusing on one single type of system – we have included all three, which indicates that we have no technology preference.

A typical certification process begins with ocean meteocean analysis - swells, waves, currents and wind record data.

The second step is a hydrodynamic study for motion analysis, to understand how the floater behaves and whether the structural design is stable enough to support the turbine.

Then there is the structural assessment to determine whether the structure has sufficient strength to withstand the wind and sea forces.

We are providing guidance on which parameters should be included, from a design point of view. For example, we look at sea bed engineering, based on the state of the seabed. Whether the seabed is sand or rock determines the anchoring system lines that link the system to the ground.

Wind Energy Update: To what extent will these guidelines impact or influence future designs of floating turbine structures?

Maxime Pachot: Early stage decisions have a significant impact on the end project.

We do want to be implicated at the very early stages of a project in order to ensure the designers include key parameters. It is no good waiting until the final stages to bring the certifier on board and have them say “yes” or “no”.

Bureau Veritas has issued a guidance note to aid designers in determining load cases, for example. If a designer proposes a design with seven anchors, we propose that they design it with seven minus 'x' lines to see if the system still works – in other words, to look at whether the loading can handle abnormal conditions. This process provides very important data for the decision maker.

Wind Energy Update: How many floating structure designs have been deployed to date and how many of these would meet certification standards?

Maxime Pachot: At present there are only two systems operational in the world. The first was Blue H in Italy, and the second was the Hywind platform in Norway. Bureau Veritas was not involved with either of these projects.

Wind Energy Update: Is Bureau Veritas working on any other floating platform projects as present?

Maxime Pachot: In France, three projects are currently in the design and engineering phase. Bureau Veritas is involved in one of these as a partner and we hope to partner in the second project as well.

We are also involved in the FP7 R&D project in Europe, (HiPRWIND), which is a non-commercial R&D project for floating wind turbine platforms. 

Wind Energy Update: Roughly how many other floating wind platform projects are in the pipeline globally?

Maxime Pachot: Many people are interested in this technology. There is a lot of interest in Europe. The US is also interested, however, we have yet to hear any official news on any key developments on floating turbine technology.

There is a big push in Far East Asia – China and South Korea are really pushing to get floating turbine technology up to speed.

We need to develop the technology quickly in order to bridge the existing technology gap is to be bridged.

Wind Energy Update: Beyond the design stage advantages that you mentioned, what other advantages does certification provide?

Maxime Pachot: The IEC, the international standards manager for the wind energy sector, is now establishing working groups to discuss floating platforms and Bureau Veritas aspires to be on the technical committee of standards.

Certification eases the work for everyone involved in the industry. It can guide the design phase by providing generally accepted methodology. Without certification, safety standards quickly become compromised. The ultimate objective is safety during installation and O&M and high relability.

Wind Energy Update: To what extent will the offshore oil and gas experience shape offshore wind standards?

Maxime Pachot: While offshore oil and gas and offshore wind are very different products, there are equivalences and common safety requirements. In this respect everyone’s experience in the offshore environment will be drawn upon to establish methodologies and minimum safety requirements.

Where floating platforms are concerned, the global knowledge is minimal. With everyone starting at the same level, certain methodologies will require rethinking.

Wind Energy Update: Bureau Veritas is the first to have issued a guidance on offshore wind floating platforms, but it is unlikely to be the last. Is there a danger of there being too many guidances and standards?

Maxime Pachot: If two guidance notes are different, this only highlights that no-one knows the best solution. There is no problem with having different approaches, so long as there is not a conflict of information.

To respond to this article, please write to the editor: Rikki Stancich