Exclusive: Sea Bridges and docking stations to reach out to inaccessible offshore turbines

Visiting an offshore wind turbine is a hair-raising experience. "It's quite a crude process," explains Phil De Villiers, head of the offshore wind accelerator scheme at the Carbon Trust. "You basically drive a small boat into the base of the turbine and then hop across."

It is as potentially dangerous as it sounds and consequently offshore wind turbines can only be accessed by maintenance teams during benign weather conditions – an issue that is set to become ever more problematic as developers begin work on the new round three offshore wind farms, some of which will be located up to 200km off the coast in notoriously rough seas.

The Carbon Trust is preparing to tackle the problem with the launch this summer of a competition designed to identify access and maintenance technologies and techniques that promise to make it easier for engineers to reach inhospitable offshore turbines.

De Villiers said the scheme would be modeled on a similar competition run by the Carbon Trust last year, which offered a prize of £100,000 to firms developing technologies that could reduce the cost of offshore wind turbine foundations. "There will be a similar cash prize, but the real prize is that you will get to work with wind farm developers who account for 40 per cent of the round three market."

The Carbon Trust offshore wind accelerator is backed by a consortium including Dong Energy, RWE, Scottish Power, Scottish and Southern Energy and Statoil, which together have provided two thirds of the funding for the £30m initiative and will work with the winning bidder.

The consortium is also already working on improving access to offshore turbines, with Statoil leading a project to build a new docking system for maintenance boats.

De Villiers explained that the so-called Sea Bridge would provide a stable, 15-metre-long bridge between the turbine and the access vessel. "It works using cables that hang off the turbine," he said. "You grab the cables and then the bridge is activated and moves along the cables to the boat, providing a secure fixed link."

According to research undertaken by the Carbon Trust, simply making it easier to access offshore turbines would boost their availability factor, the percentage of time they are available during the year, by two percentage points.

However, De Villiers said that the potential increase in availability for the deep-water round three projects is likely to be far higher. Experts have expressed concerns that some of the proposed sites, such as the Dogger Bank zone up to 200km off the shore, are so difficult to access that a turbine breaking down at the start of the winter would have to be left for months before it could be fixed.

The Carbon Trust's offshore wind accelerator is just one of a number of high-profile projects aiming to improve the reliability and resilience of offshore wind turbines.

The Energy Technologies Institute is also backing a number of design projects intended to improve maintenance practices, including the NOVA project to develop a vertical axis wind turbine where all major maintenance work could be undertaken at the base of the system.

Similarly, GE has confirmed that all its new offshore wind turbines will be gearless, in a move designed to improve their reliability and reduce downtime.

Meanwhile, some experts have even mooted that future offshore wind turbines could have maintenance teams living onsite within the tower of the turbine.