The Crown Estate, which owns the UK seabed, awarded development licenses for so-called “Round 3” wind farm sites in mid January. The nine chosen sites are in deeper waters than ever before, making foundation innovation critical to delivery.

“Steel monopiles will not be suitable in 30m depths, there’s a certain point at which they no longer work,” said Atkins energy managing director Martin Grant.

Most offshore turbines around Britain are in water 20m deep or less. Yet 70% of the new raft of wind farms will be in depths of 30m or more, with some reaching 60m.

The Carbon Trust, an independent company set up by Government to help reduce carbon emissions and commercialise low carbon technologies, is working on developing the technology necessary for round three.

“It’s a completely different engineering challenge to embed these turbines,” said Carbon Trust senior technology acceleration manager Benj Skyes. “New technology is needed for deeper water conditions and larger, heavier turbines.

“However, the big challenge is ensuring this new technology is commercially viable.”

Four new foundation prototypes are being trialed by the Carbon Trust in partnership with the engineering firms that designed them.

Consultant Gifford is pioneering a large precast concrete gravity base structure, which is placed on the seabed. Wind turbine masts will then be built onto the base. Stability will be provided in water depths up to 45m.

The structure will be ferried to site using submersible barges, avoiding the use of heavy crane barges and offshore jack-up platforms.

Dutch firm Suction Pile Technology has put forward a self-installing foundation solution. A tripod structure is set on three suction piles that are “sucked” into the soft sea bed, taking away the need to drive piles.

Ballast is incorporated into two of the suction piles to reduce the tensile loads and make lowering the device into water easier.

Keystone Engineering is developing a “spider-like tripod” with three supporting legs angled around a central pile in a twisted jacket.

The final prototype is US firm Glosten Associates’ floating wind turbine, which comprises a buoyant hull, tendons and an anchorage system.

If successful these technologies will be available for early round three projects.

Foundations currently account for half the capital cost of offshore wind farm development. The Carbon Trust predicts the four prototypes can reduce installation costs by up to 20%.

WINDS OF CHANGE

Offshore wind is expected to be a much-needed shot in the arm for the UK construction industry. Over £75bn will be invested into building the nine wind farms, and up to 70,000 jobs will be created.

British Wind Energy Association head of offshore renewables Peter Madigan said: “There will be a massive step change in supply and installation. There needs to be a phenomenal growth of an industry that is very much in its infancy in the UK.

“Experience from the oil and gas industry will, of course, be utilised, but there is enormous scope to build on existing engineering knowledge.”

The engineering community has told GE that it is up to the challenge of building the necessary skills.

“The UK can definitely step up to the skills challenge. There is enough expertise in this country to deliver these wind farms,” said Atkins energy managing director Martin Grant.

Currently one turbine is installed in the UK every 11 days. This rate needs to pick up to 2.5 turbines per day by 2017.

Gemma Goldfingle