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7.
June
2017.
SENSE cuts deep offshore costs
SENSE cuts deep offshore costs

Study shows new installation and maintenance technology will help industry go farther and deeper without jack-ups

A revolutionary new approach to offshore wind turbine installation and maintenance could cut the cost of energy from future deepwater sites by around 9%.

The results of a £200,000 Innovate UK Energy Catalyst study involving detailed engineering analysis on the Self Erecting Nacelle System (SENSE) show the new technology could also trim 4% from the cost of energy at current wind farms in relatively shallow water.

There is currently no proven technology capable of installing the next generation of turbines and towers on foundations in water depths greater than 60m apart from building ever larger and more expensive jack-ups and semi-subs.

SENSE Offshore Limited, which is developing the technology for commercial roll out in 2021, says its system means large jack-ups and crane vessels are not needed to install the turbine nacelle and rotor or for maintenance including the change out of major components.

SENSE is a modular, removable transport and installation system mounted on a standard large construction vessel.

SENSE Offshore MD Patrick Geraets says: "Wind turbines are getting bigger and developers want to exploit deep water sites. How are these turbines going to be installed? SENSE is an answer - faster, cheaper, independent of water depth, with world wide application and it is scalable to the larger turbines coming to market in the next five years."

SENSE transports a pre-assembled and tested rotor nacelle assembly on board a large multi-purpose construction vessel andhas solved the problem of transferring 700+tonne loads in significant wave heights from the vessel to the tower. The SENSE transportation carriage then carries the turbine to the top of the tower on rails.The process is reversible for maintenance and replacement.

The Innovate UK Study was carried out for SENSE Offshore by a project team of leading contractors including GBG, PHG Consulting, Industrial Systems and Control, BVG Associates, Knowtra and James Fisher Marine Services.

It found the SENSE System could cut around €125m from the capital expenditure (CapEx) on a €5.1bn, 1200MW wind farm in waters in excess of 70 metres and save €28.5m a year in operating expenditure (OpEx). On a shallower large site where water depths are similar to North Sea farms currently being built with jack-ups, SENSE could save €84m in CapEx and €10m in OpEx per year.

SENSE Offshore is nowplanning the next stage of development to bring its technology to market within 4 years. Geraets says: "To do this we need to significantly accelerate the pace of development, for which we need both investment and industrial partners." 

The company is looking for partners and investment to add to an Innovate UK Energy Catalyst application that is currently under way for an award of up to £1.5m. This project will carry out detailed design and engineering and onshore scale tests to demonstrate the SENSE System in preparation for undertaking a full-scale test offshore. 

"A partner or investor could be an existing construction company looking to expand its offering to the offshore wind industry to include large turbine installation and maintenance, or a new entry eyeing this growing and substantial market," says Geraets.

For further information please contact:

Patrick Geraets, MD SENSE Offshore, on +44 7770 478 492

patrick@senseoffshore.co.uk

Or visit our website:www.senseoffshore.co.uk

Additional and high resolution images can be provided on request.

NOTES TO EDITORS and TECHNICAL DESCRIPTION

SENSE Offshore was established by Patrick Geraets and George Ballard. Patrick, a Chartered Mechanical Engineer, has a track record of managing technical innovation with over 28 years' experience in the wind industry as well as the offshore oil and gas industry.

George Ballard has extensive experience deploying innovation and unique technology developments to solve specific problems as well as providing structural and engineering design resources via his GBG Group companies, particularly GB Geotechnics Ltd and consultancy GB Consultants Ltd.

Innovate UK project

The Innovate UK Project was an Energy Catalyst early stage award. The objective was to confirm the practicality of SENSE by undertaking detailed engineering analysis of key areas and to confirm the projected cost of energy savings. The total budget was £200,000 over a project programme of 9 months.

Project partners:

PHG Consulting Ltd- wind and tidal energy consultancy providing secondment of management and technical resources

GBGtechnology consultancy providing secondment of management and technical resources

Industrial Systems and Control Ltd- a leader in the field of control systems for mechanical handling with direct experience of delivering successful projects in the UK marine environment. ISC is developing the control system and sensors for the vessel to tower transfer system.

BVG Associates Ltd- provides industry leading consultancy on economics, supply chain, project due diligence, technology review and energy policy. BVG has developed a special LCoE cost model for SENSE and provides supply chain and market information as well as general assessment of technology trends and comparisons.

Knowtra Ltd- expertise in ocean modelling and statistical simulation of weather downtime for vessels working in renewables, oil and gas and use of ports. Knowtra has developed a special marine operation model which interfaces directly with the BVG cost model.

Mojo Maritime Ltd / James Fisher Marine Services Ltd- is a project management, engineering and consultancy services with particular expertise in wind, wave and tidal energy. JFMS has undertaken a review of the SENSE concept and is providing advice on marine operations and vessel types, specifications and selection.

TECHNICAL DESCRIPTION

How SENSE works

The nacelle and rotor are assembled at the dockside with the rotor flat and the nacelle vertical. The transport carriage is fitted.

The transportation and handling system is mounted to the deck of a large construction vessel and the turbine carriage system interfaces with it. Two or three rotor assemblies can be transported on each construction vessel.

The construction vessel transports the rotor assemblies to the wind farm where towers have been pre-installed by a crane vessel in the usual way. Each rotor assembly slides on rails onto a handling system on the vessel,which uses a six degrees of freedom motion compensated platform to target and co-ordinate transfer to thetower rails. Once the rotor assembly is locked onto the tower the installation vessel detaches and moves away to install another turbine.

A power and control umbilical is plugged into the wind turbine power system and the rotor assembly is raised up the tower on the multi-use transport carriage. This clamps to and climbs the ratchet rails on the tower. The blades lie horizontally and the rotor assembly is supported at its centre of gravity and locked vertical with a ram fitted to the transportation unit until it reaches the top of the tower.

At the top of the tower the rotor assembly is rotated around the attachment pivot by a hydraulic arm. Once horizontal the transport carriage lowers the rotor assembly on to the top of the tower for bolting. When it is secured the transport carriage is lowered to the bottom of the tower for collection by the construction vessel which heads back to port for more turbines.

How SENSE makes savings

Capital expenditure (CapEx) savings derive in part from the use of more readily available construction vessels at competitive prices that can be mobilised at shorter notice compared to crane vessels. The concept easily scales to projected 10MW+ turbines, while the market may not so quickly provide large crane vessels to keep pace with this development curve.

In addition conventional installation methods average around 24 hours per turbine but using SENSE turbines can be installed in parallel by multiple SENSE equipped vessels leading to a shorter construction programme. Rapid installation rates significantly reduce the construction finance risk profile and interest costs of large wind farms by generating early revenue.

In turn weather-critical operations are shorter duration so can take advantage of narrow weather windows. Only one short "lift" operation is needed to transfer the rotor nacelle assembly onto the tower base rails, which can be completed quickly with minimal vessel time on station. The rotor nacelle assembly can remain at the base of the tower if necessary until a suitable weather window is available.

Operating costs (OpEx) also see significant savings as large crane vessels are not needed for major component replacements, leading to lower refurbishment costs mid-life and lower OpEx costs in the later years of operation. In the event of a major failure, rather than replacing the individual major component the complete nacelle and rotor assembly can be "swapped out" getting the turbine back up and working in one weather window.

During the operations phase, SENSE can be used to improve access for external inspections of the turbine. In particular it can provide a mounting for a secure platform for blade inspection and repair.

By reducing overall O&M costs and increasing the turbine availability to levels now normal for onshore wind farms, SENSE will help offshore projects move towards a "least cost €/MWhr sweet spot".