GENERAL OVERVIEW

OF THE PROJECT




SUMMARY


ATOMS is a 2-year project financed by the European Commission under the BMFF Funding Opportunities program supporting Blue Growth. It started in September 2020 with a total budget of €3,545,109.02.

OPEX accounts for approximately 30% of the cost of offshore wind energy and is thus a critical factor in the path to further reducing the cost of this strategic energy source. Nearly half of this OPEX is dedicated to paying for the large jack-up vessels that are, as of today, the only option to perform any so called Large Corrective Maintenance (LCM) interventions, dealing with the replacement and handling of major components of offshore wind turbines.

ATOMS (Attachable Towable O&M System) project will complete the development, prototype, certification and fully demonstration in real operative offshore conditions of a pioneer technology for turbines’ Large Corrective Maintenance actions which will -for the first time- scape the monopoly of jack-up vessels and will drastically reduce the maintenance cost of bottom-fixed wind turbines. What is more, ATOMS shall demonstrate and provide a simple and yet breakthrough solution to one of the key unsolved technological challenges for the future of the offshore wind sector: how to perform on-site Large Corrective Maintenance operations in floating wind turbines.

Not only will our solution slash to nearly 1/5 the costs currently dedicated to jack-up services for the maintenance of bottom-fixed turbines, resulting in a 35% reduction in current OPEX but it will also fill the technological gap existing in floating offshore market when dealing with LCM actions.

At last but not least, the ATOMS project will also have a measurable impact on employability and environment. On the one hand, ATOMS’ considerably sophisticated yet simple solution is expected to positively impact local economy growth both through direct hiring and indirect spending. On the other hand, its environmental impact will be much lower when compared to existing solutions in respect to CO2 emissions and seabed conditions, without affecting marine flora and fauna by not needing to be supported on the seabed as conventional O&M jack up vessels.



3.5M
budget (€)
2
year project supported
by the EC H2020
-50%
reduction of
environmental
impact

METHOD


The idea behind the ATOMS technology is reasonably sophisticated in practice, undoubtedly powerful in its problem-solving capabilities, and yet quite simple in concept: while jack-up vessels reach deep down to the seabed for a fixed point to prevent movements of the crane, ATOMS will instead reach out to the nearby support structure of the wind turbine, to which it can conveniently couple.

For bottom-fixed wind turbines, this will make it possible to virtually null the movements of the service crane. Floating wind turbines, however, cannot be kept still, but ATOMS does not need to, for it is not absolute movements of the turbine but rather relative movements between the service crane and the turbine that matter for the required crane operability. ATOMS will ensure that crane and turbine move along as one solidary body, thus nulling any relative movements and making it possible for the service crane, under adequate weather conditions, to reach turbine components as needed. As such, the key technological development supporting the ATOMS technology is the coupling system which can allegedly enable such a rigid connection. This is an ambitious technological challenge, but it is precisely one of the factors which strengthen the case for the ATOMS technology: such a key and novel coupling system already exists, has in f act been very successfully proven offshore for an analogous purpose and is ready for free to the present project, as will be next explained in detail. Three components form the backbone of the ATOMS system: a mid-size floating twin hull barge, a self-hoisting crane and the coupling ring structure (CRS).

General view of the Coupling Ring Structure (CRS). It is equipped with high strength hinges which allow for opening and closing of the ring around the tower, as well as with specifically designed hydraulic rippers with the capacity to “grab” the tower for a robust coupling capable of adequately resisting the clamping forces which may be generated during the large corrective operative. A total of 12 grippers are provided, 6 in each level.

Detailed view of the hydraulic grippers in the CRS. A 300tn hydraulic jack makes it possible to adapt the position of the gripper to adapt to variable tower geometries. The lever configuration of the grippers allows it to resist clamping forces of 1000tn, significantly larger than the maximum design forces expected for a LCM operation. The force and position of the gripper can be monitored and controlled remotely at all times.

Main components of the ATOMS platform as they will be assembled onshore: (i) A mid-size floating twin hull barge, (ii) Self-hoisting crane and (iii) Coupling ring structure, robustly connected to the twin hull barge.

BARGE

A mid-size floating twin hull barge with maximum length ranging from 20 to 30m depending on the circumstances of the project and the LCM intervention.

The preferred option would consist of the use of modular barges, which can be rented and delivered to virtually any location in the world and be arranged to provide the optimum barge size. Commercial modular barges suitable for work in open waters are available in the market. These modular barges may be bought or rented as needed.The sizing of the barge will be strictly enough to support the weight of the crane with enough freeboard, provide adequate stability during towed transport and generate sufficient working and storage area. Neither of these requirements demands for a large barge, and as a result the chosen dimensions can be moderate, which reduces both the cost and the maximum loads which may act on the Coupling Ring Structure and the tower substructure itself.

The central part of barge will as rule require specific reinforcements to adequate cope with the forces transmitted by the Coupling Ring Structure (CRS). For this, a standard module may be adapted as needed or specially built central module compatible with the remaining standard modules can be built at low cost (low 6 figures). Depending on the tidal range, the barge can be equipped with a ballast system capable of letting water in and out the barge while it is fixed to the tower, in order to adapt to the variations in the water level while the barge is fixed and coupled to the tower.

SELF-HOISTING CRANE

ATOMS technology makes it possible to use available self-hoisting cranes, whose reference day tariff is two orders of magnitude lower than that of a large jack-up vessel.

Hydraulic cranes with telescopic boom will be preferably used, since they allow to conveniently retract the boom during the towed transport, and deploy the boom once the barge is still and coupled to the tower. However, depending on the circumstances of the project and characteristics of the LCM intervention other crane types may be considered.The crane can be conventionally mounted and properly fastened aboard the barge. As previously mentioned, this is common practice in many marine works. The breakthrough innovation of the ATOMS technology is the way in which this barge can be kept sufficiently still for the crane to operate reaching up to the turbine.

COUPLING RING STRUCTURE (CRS)

The most distinctive and key component of the system, the CRS is a high-capacity ring which can open and close around the tower.

It is equipped with hydraulic grippers which make it possible to exactly adapt to different tower geometries and to control and monitor at all times the clamping forces that are generated in all the contact points between the tower and the CRS. The dimensions of the ring structure and its contact points with the tower must be adequately designed to ensure that all loads to be transmitted can be adequately bared by tower structure.

The preferred option would consist of the use of modular barges, which can be rented and delivered to virtually any location in the world and be arranged to provide the optimum barge size. Commercial modular barges suitable for work in open waters are available in the market. These modular barges may be bought or rented as needed.

The sizing of the barge will be strictly enough to support the weight of the crane with enough freeboard, provide adequate stability during towed transport and generate sufficient working and storage area. Neither of these requirements demands for a large barge, and as a result the chosen dimensions can be moderate, which reduces both the cost and the maximum loads which may act on the Coupling Ring Structure and the tower substructure itself.

The central part of barge will as rule require specific reinforcements to adequate cope with the forces transmitted by the Coupling Ring Structure (CRS). For this, a standard module may be adapted as needed or specially built central module compatible with the remaining standard modules can be built at low cost (low 6 figures). Depending on the tidal range, the barge can be equipped with a ballast system capable of letting water in and out the barge while it is fixed to the tower, in order to adapt to the variations in the water level while the barge is fixed and coupled to the tower.

Hydraulic cranes with telescopic boom will be preferably used, since they allow to conveniently retract the boom during the towed transport, and deploy the boom once the barge is still and coupled to the tower. However, depending on the circumstances of the project and characteristics of the LCM intervention other crane types may be considered.

The crane can be conventionally mounted and properly fastened aboard the barge. As previously mentioned, this is common practice in many marine works. The breakthrough innovation of the ATOMS technology is the way in which this barge can be kept sufficiently still for the crane to operate reaching up to the turbine.

It is equipped with hydraulic grippers which make it possible to exactly adapt to different tower geometries and to control and monitor at all times the clamping forces that are generated in all the contact points between the tower and the CRS. The dimensions of the ring structure and its contact points with the tower must be adequately designed to ensure that all loads to be transmitted can be adequately bared by tower structure.


RESULTS


The result will be a real scale prototype of a structure to perform large corrective actions both in bottom-fixed and floating offshore turbines without relying on scarce and expensive jack-ups or vessels. The final objective is reducing costs on O&M actions for offshore wind turbines thus contributing to make it more affordable to society in general.


The main advantages are


Independence of scarce and costly jack-up vessels.


Perfectly suited for deeper water wind farms.


Reduction of 35% in current OPEX.


Rely only on conventional and ready-available tugboats and land cranes.


Directly applicable for new emerging markets.


Suitable to fill the technological gap existing in floating offshore market when dealing with LCM actions.


Quick response time to reduce the unproductive time of turbines requiring service.


Suitable for a major part of bottom-fixed and floating substructure typologies.


Significant reduction of environmental impact due to its independence from jack-ups.


Applicability to floating wind turbines.


Complementarity with Esteyco’s ELISA’s substructure technology.


Very intensive in local content of workforce, raw materials and installation means.