A Scottish company has developed an installation system that offers the potential to revolutionise the installation of wind turbines offshore. Two variants of the technology have been drawn up – one to handle steel monopile foundations, the other for the concrete gravity base equivalent.
One of the firm’s founders claims there is a major business to be built around the ideas and that the Cromarty Firth would be an ideal place to manufacture the systems in association with integration/fabrication of the turbines, towers and foundations.
Behind the bold concept is the Inverness company, Concrete Marine Structures, which was set up in 2008 by Rodger Taylor and Charles Goodall, both of whom have a 40-year track record in marine engineering, plus Taylor has been involved with marine contracting, plus designed and built concrete floating structures for the fish-farming industry for which he was awarded the John Logie Baird Certificate for Innovative Design in the mid-1990s.
“As marine engineers, we followed with interest the development of the Beatrice Wind Farm Demonstrator Project, with particular regard to the structural support foundations for deepwater windfarms,” Taylor told Energy.
“The technical report by Talisman Energy (W/61/00635/00/REP) highlighted the problems and costs encountered during the installation which, until resolved, threaten the economic viability of offshore windfarms. At present, potential development of deepwater offshore windfarms is constrained by the cost of the turbine support foundations, which are generally derived from platform technology pioneered by the oil industry.
“In order to justify the cost of turbine foundations in deep water, the industry is developing ever larger turbine generators without addressing the fundamental problems associated with offshore turbines.”
According to Taylor these include:
Cost-effective foundations.
Access to the turbine generator and blades for repairs and maintenance.
Commissioning of the electrical systems at quayside.
Scour protection.
Access to the working platform for small craft.
“We have endeavoured to engineer a fully integrated solution to these problems which will considerably reduce the construction, operating and maintenance costs of offshore windfarms.
“Our patented concept, based on the installation of 5MW turbines or larger in water depths of 50m addresses the issues identified by Talisman Energy during the implementation of their demonstrator project.”
While the CMS technology initially focused on the installation of steel monopiles, the company has since morphed this into also being capable of handling concrete substructures.
Taylor believes concrete eclipses steel when it comes to turbine foundation structures, including winning on cost by a sizeable margin. The main support column would be built with precast concrete rings to simplify and speed construction and he says a design life of 100 years is perfectly feasible.
The CMS method of construction and installation eliminates the need for heavy-lift ships or large jack-up pontoons and craneage offshore. It allows for the following:
The foundations (either in concrete or steel), turbine tower, nacelle and blades to be built and delivered as one unit.
Enables the turbine foundations, main support column and turbine tower to be manufactured by any fabricator and delivered to a dedicated assembly and construction yard with good quayside facilities.
The commissioning of the turbine at the quayside with the main power transmission cables installed.
The turbine tower delivered in a stowed position before final erection after the foundations are secure on the seabed.
Lay the main power cables between turbines.
The lowering of the turbine tower and blades for major repairs while on site.
The main support column is cable-stayed for additional stability and provides access for small craft to the working platform.
The key to the approach developed by Taylor and Goodall is a specially designed multipurpose, self-propelled, reusable pontoon/collar that performs a number of functions. The device has been conceived to be capable of:
Providing stability during delivery.
Delivering and installing a complete unit.
Placing sand ballast.
Installing and securing piles.
Providing a stable platform to carry out major repairs and maintenance post-construction.
Installing the main power transmission cables between turbines.
Placing scour protection.
Removal or relocation of complete turbine units through reverse engineering of the original installation process.
Taylor said: “In order to meet Government targets for renewable energy, we consider our design offers a realistic, practical and cost-effective solution to the problems identified in the Talisman report, not only in UK waters, but offers considerable export potential worldwide.
“Reaction within the wind industry to our design has been very positive and has encouraged us to seek partners in order to develop the concept to its full potential.”