Taking technology, which has been successfully deployed in the offshore oil and gas industry, marine engineers have now developed and patented an articulated wind column (AWC) which can support an offshore wind turbine.
This has the potential to unlock vast areas of deep water around the UK and around the world by making offshore wind turbines economically viable.
The device has been designed to provide structural support in offshore waters ranging from 45m to 200m for the largest wind turbines currently available (8MW).
This invention – developed by ODE (part of the DORIS Group) and Marine Engineering Energy Solutions (MEES) – has been shortlisted in the UK 2016 Energy Innovation awards.
The origins of the AWC’s design lay in the concrete articulated column developed by the DORIS Group for the Maureen oil platform in the North Sea in the 1980s. The structure was operational until the field was decommissioned in 2001. In addition, a further 12 articulated loading columns were installed in the North Sea, some of which are still in operation.
The AWC structure consists of a compliant concrete vertical column and the concrete base, which is located on the seabed. The two main parts are connected by an articulated joint, which allows rotation about both horizontal axes.
The AWC uses the buoyancy in the deeper water to maintain the support structure near vertical, resisting the forces from wind, current and waves. It can be located where the power is needed, closer to shore, reducing significant installation and operation costs.
In the UK to date, the development of offshore wind turbines has been restricted to relatively shallow water locations of less than 40m, with many planned sites being a considerable distance from shore – resulting in high electrical transmission costs.
The design enables the structures to be produced in high volumes and at lower cost. It also allows for installation on an uneven seabed without the need for seabed preparation, delivering the potential for a lower levelised cost of energy when compared to conventional offshore wind solutions.
The development of deep-water locations within the 25km range will allow for shorter cable connections to shore, and eliminates the need for the adoption of transformer units, which would provide a significant component to the overall development costs.
ODE managing director Peter Godfrey said: “The AWC is based on a proven, robust technical solution suitable for the harshest environmental conditions. It has a simple installation and removal process, based on a design successfully used by the oil and gas sector in the North Sea for many years.
“It provides an excellent example of the ongoing transfer of skills and knowledge from the oil and gas industry to the renewables sector as we seek to develop viable alternatives to hydrocarbon use.”
MEES director Otto Carlisle added: “Conventional offshore wind and support structures are economically viable in up to 30 or 40 meter water depth. This constraint significantly reduces the area around the UK and other countries in which wind farms can be located. It can also drive wind farms further from shore, which increases the levelised costs of energy.
“Successful tests and years of practical experience from deployment in the oil and gas industry have demonstrated that the AWC can be used as a means of support for large wind turbines in deeper water at relatively near shore locations. This system now allows for the economic development of offshore wind technology at many near to shore sites around the world.”