Jettisoning ballast

Wednesday, 14 October, 2015 - 16:45
It may not be a living room, but the Blade Repair Habitat from GEV ­Wind Power certainly turns a rotor blade into a weather-independent workroom. (Photo: GEV Wind Power)
It may not be a living room, but the Blade Repair Habitat from GEV ­Wind Power certainly turns a rotor blade into a weather-independent workroom. (Photo: GEV Wind Power)

There is still plenty of potential for cost reduction in the offshore wind industry, and this is a good thing. But where exactly does that potential lie, and how much is there? OWI set out to find the answers to these questions.

Cost reduction is the magic phrase that resounds through the halls and conference rooms at every single offshore wind energy industry event. This was true at the EWEA Offshore in Copenhagen at the beginning of this year, and it will also be the case at both the ­Windforce in ­Bremerhaven and the Global Offshore Wind in London. One does not need to be able to see the future to predict that.

Cost reduction is something that politicians often call for. Offshore wind energy can only be a real alternative for the energy supply of the future if it manages to reduce its electricity production costs. However, cost reduction has also become the magic phrase for marketing experts. Products and services that help to reduce costs are in high demand, and for this reason they are touted to politicians who demand them, to consumers who want to have them and to journalists who ask ­questions about them.

In a nutshell

So we asked. OFFSHORE WIND INDUSTRY wanted to know exactly how much cost reduction potential there is in the offshore wind industry. Specifically, we asked about new products, innovative solutions and advanced approaches that companies have recently launched or are now market-ready. To do this, we wrote to more than 1,000 companies in the offshore wind industry and asked about their ideas for cost reduction. They were allowed to submit anything, including products, ­services or concepts.

The response was overwhelmingly positive. Many companies replied and shared their ideas with us (see table). Unfortunately, their submissions were not always as precise as we would have wished for. Our question really was quite specific: how much money can your solution save per megawatt hour? We understand, of course, that it is not always possible to provide exact information on savings, measured in €/MWh. However, we did find it hard to understand that some companies were unable to provide information that was anywhere near exact. In many cases, we were offered the usual empty marketing phrases instead.

In our opinion, this raises an important question: how can a company advertise cost reduction potential if it is not in a position to provide any information comparing that potential to other solutions? Could it be that companies are not always entirely sure that their solutions are actually less expensive than competitors’ ­products? Or is it that they simply use the popular phrase ‘cost reduction’ because hardly anyone ever asks for more specific information? At any rate, we were generally more convinced by solutions that provided specific information. Some of them deserve to be presented here.

Fundamental potential

The foundations of offshore wind turbines seem to offer a particularly high potential for savings. Several approaches focus on these components. OWT Offshore Wind Technologie GmbH, MHI Vestas Offshore Wind and IMS Nord, for example, are planning to revitalise the market for tripods. After getting crushed under the wheels of the monopile’s triumphant advance, it will now once again be offered as an option for the new MHI Vestas 8-MW turbine. A total of 128 tripods have already been installed for 5-MW turbines in the North Sea. The V164-8.0 turbines have 60 % more power, but only 13 % more material would be needed to make tripods sturdy enough to support them. This means that the cost of constructing foundations for a 400 MW offshore wind farm could be reduced by 25 %.

Salzgitter AG is focusing on a different foundation structure and, in particular, the process needed to manufacture it: the jacket foundation. Rather than producing them individually, which is expensive, the company will be using standardised construction kits made of industrially produced pipes. This way, only orbital welds are needed for assembly. A standardised jacket design is a prerequisite for this. If this can be implemented, ­Salzgitter is confident that cost savings of up to 30 % can be achieved compared to individual production.

Universal Foundation A/S is focusing on a mono bucket foundation. It is installed using a jet and suction system as the driving force. Lowering the pressure in the cavity between the foundation and the seabed generates water flow, which lowers resistance around the edge of the foundation’s skirt and allows seabed penetration. This reduces the costs because the mono bucket does not require divers and, in most cases, also does not require seabed preparation. There is little or no need for scour protection. Installation of the foundation requires no ­additional sound protection systems. Compared to a reference monopile foundation, the construction of a mono bucket delivers cost reductions of approximately 10 to 15 %. During the installation, a further cost reduction of 50 % can be achieved.

RED Bernard GmbH’s idea is also aimed at saving costs on the foundation. RED is developing vibration absorbers that will compensate for vibrations in the towers that are caused by waves. The company will be installing liquid dampers in the towers of wind turbines. They will equalise the vibrations in the towers using counter-vibrations. This principle is widely used in high-rise construction. The improved structural damping will allow the thickness of the tower walls to be reduced. When all potential effects are taken into consideration (such as the tower, foundation, assembly and transportation) RED is confident that savings of up to 50,000 €/MW can be achieved. Wow.

Transporting and handling foundation structures can incur significant costs, so BLG Logistics Group has developed an innovative logistics concept. The company has equipped the special pontoon vessel ‘­Offshore BHV 1’ with a sea fastening system that secures the cargo similar to the way containers are secured. Instead of a welded structure, it uses a flexible load frame system that can be locked in place and reusable fittings to secure cargo on deck. The pontoon vessel’s efficient ballast system (2,400 t/h) makes it possible to rapidly load and unload the vessel using its rail-guided cart system. BLG calculates that the lower operating costs compared to using a crane, the lack of standby times and the negligible cost of mobilisation and demobilisation will result in savings of 25,500 €/MWh.

A living room on the rotor blade

GEV Wind Power is optimising maintenance work with its innovative Blade Repair Habitat. Unfavourable weather currently accounts for around 40 % of cancelled maintenance days. GEV’s Habitat structure will minimise the weather risk, enabling a technician to complete essential work in a controlled environment. As a result, it is expected to save the wind energy sector between three and five lost days every maintenance season, potentially returning a minimum of 1 to 2 % increase in annual energy production. These advantages do not take into account the added benefit of a longer maintenance season or the ability to work in shifts because of the availability of artificial lighting, thanks to the protection provided by the Habitat.

DualLift GmbH has developed a new drive system for service lifts. The UpMax system uses chains instead of ropes. They have a longer service life and only need to be replaced every twenty-five years, according to ­DualLift. A redundant pair of drive motors improves safety, and at an average cost of € 7,500 for a service lift, DualLift estimates the total savings to be 30 %.

Harting Deutschland GmbH & Co. KG is also focusing on equipment for wind turbines. In order to cost-effectively assemble system components, connectors are needed that allow rapid connection and, if necessary, replacement of electrical systems. For this reason, Harting has developed prefabricated cable systems with plug-in electric connectors. This reduces the amount of time that installation teams need for their work, and installation vessels and construction machines spend less time on the high seas. The cost savings during installation adds up to 2,000 €/MW. The same amount can be saved annually in operating costs. At an annual output of 4.2 million MWh and a service life of 20 years, the savings is 0.5 €/MWh. Harting clearly put considerable effort into providing specific figures, and we commend them for that!

Planning for the weather

The activities of weather service providers and logistics companies are a clear indication that there is plenty of savings potential during the installation phase. Met Office’s marine archive database provides access to a consistent source of information on the marine environment and therefore a better understanding of how conditions are likely to be throughout the lifetime of the wind farm. The Met Office can quantify the savings potential for the operational phase: A round trip to a wind farm by a transfer boat can use up to 0.5 tonnes of fuel. Supposing fifteen boats had to turn back due to bad weather and wait three days in port for better weather, this would result in additional labour costs and wasted fuel costs of more than € 16,000.





The new AC grid access solution from ­Siemens consists of an Offshore Transmission Module (OTM), which is directly connected to a turbine and installed as a distributed transmission set. (Graphic: Siemens)


GRS Global Renewables Shipbrokers GmbH is also providing a service aimed at reducing the cost of supply trips to offshore wind farms. Cargo Run is a vessel sharing model that combines the cargo from several clients and delivers it to the corresponding wind farms. Wind farm operators simply communicate their individual transport requirements to GRS as the logistics intermediary. GRS combines the requirements, coordinates them and arranges the transport with a shipping ­company. GRS estimates that customers will save 0.1456 €/MWh, but they will also save time because GRS takes care of organisation and coordination.

Siemens is making sure it keeps control over service trips with its Service Operating Vessels (SOV) concept. See page 18 for details. For wind farms that are located more than 70 km off the coast, Siemens expects to be able to reduce weather-related downtimes, which are currently between 40 % and 45 %, to between 10 % and 15 % and also to reduce maintenance costs by 20 % to 30 %, using its proprietary remote diagnostic capabilities. Siemens is looking to achieve an additional CAPEX cost reduction using the Offshore Transmission Module (OTM). This alternative to conventional transformer platforms is small and light enough to be installed on the same foundation as the turbine. This reduces installation time by 20 % and eliminates the need for a special heavy-duty crane ship.

The current solution for measuring local wind conditions is to install a rather costly meteorological mast (€ 15 million). Wave buoys and weather forecasting models are used to measure sea conditions. This is cheaper and easier with individually equipped LiDAR buoys (see also page 24) from AXYS Technologies. Their ­WindSentinel Floating LiDAR solution enables monitoring of many key parameters required by offshore wind farm developers. AXYS equips a NOMAD buoy with ­relevant sensors such as dual-LiDAR systems, current sensors, and wave sensors and is also able to install ­other sensors required by its clients. According to AXYS, a total of 0.32 €/MWh can be saved.

A new software tool from Overspeed GmbH & Co. KG provides support during the development of an offshore wind farm. ‘Wind & Economy’ defines wind farm scenarios consisting of wind climate, turbine types, hub height, models used to calculate the energy production, electrical grid layout, and economic parameters. Using LCOE as an economic performance key indicator helps to benchmark different approaches and select the optimised design. By factoring in data on the uncertainty of energy production and the cost of energy, the cutting-edge meteorological and wind farm models produce very reliable results. Potential cost savings according to Overspeed: 5 % to 30 %.

Katharina Garus

Company Cost reduction solution (keyword) Estimated cost reduction
AdBm Technologies Noise abatement Installation costs lowered by € 9,800 per foundation
Alstom Renewable Germany GmbH Overall optimisation of wind turbine, series production n/a
AXYS Technologies Inc. WindSentinel Floating LiDAR 0.32 €/MWh by 2025 
Bachmann electronic GmbH/Bachmann Monitoring GmbH Condition Monitoring System n/a
BASF SE Offering special grout material and grouting method up to 5 %
BLG Logistics Group Innovative logistics chain 25,500 €/MWh
Conveni GmbH Hydraulic yaw system € 80,000 to 100,000 for a 3 MW turbine
Deutsche Windtechnik Service Optimised carbon brush holder for the generator slip ring n/a GmbH Operational optimisation of wind turbines - digital lifecycle report n/a
DualLift GmbH Chain lift UpMax At an average cost of € 7,500 for a service lift, total savings are estimated to be approximately 30 %
Ephy-Mess GmbH Taking optimised construction designs into account n/a
ForWind - Zentrum für Windenergieforschung Large-scale research infrastructures depends
FoundOcean Grouting n/a
GEV Wind Power Blade Repair Habitat for works in a controlled environment Overall annual energy production increase of around 2 %
Grenaa Motorfabrik A/S On-site machining & repair of gearboxes 6 to 8 €/MWh
GRS Global Renewables Shipbrokers  GmbH GRS Cargo Run 0.1456 €/MWh
Harting Deutschland GmbH & Co. KG Modular cable assemblies with electric plug-in connectors 0.5 €/MWh; for an example see text
Kisters AG LCAM (Life Cycle & Asset Management) n/a
KK Wind Solutions Circuit board repair and life extension  Depending on site conditions
Leine Linde Systems GmbH ADSR - slip ring with diagnostic system; includes status reporting n/a
Met Office Weather Difficult to quantify; for an example see text
Moventas Condition Monitoring n/a
Noske-Kaeser GmbH Offering HVAC and fire fighting for offshore substations from one proven source n/a
OilDoc GmbH Knowledge sharing for proactive maintenance and condition-dependent oil analyses n/a
Open Ocean Weather analytics and visualisation Metocean Analytics and installation phases 4 months time saving on average during planning
Overspeed GmbH & Co. KG, Wind & Economy Strategic Optimisation Software 5 to 30 %
OWT Offshore Wind Technologie GmbH, MHI Vestas Offshore Wind A/S, IMS Nord GmbH Tripod foundation of Vestas V164-8.0 25 % for the foundation supply to a 400 MW wind farm
Pronomar B.V. Drying systems and MERUS technology Savings for a vessel: € 100 to € 575 a day; costs of MERUS rings for the first 5 years: € 8 to € 50 a day
RED Bernard GmbH Vibration damping for towers (liquid dampers) up to 50,000  €/MW
Rewitec GmbH Wear and friction reduction of gears and bearings 5 %
Rock Seven RockBLOCK n/a
Salzgitter AG Construction kits for the industrial production of jacket foundations 30 % compared to individual production
Scada International A/S Predict maintenance issues and save cost Depends on the WTG's
Schaeffler Technologies AG & Co. KG Innovative solution against White Etching Cracks n/a
Senvion 6.2M152 wind turbine Yield increase of 20 % and lifetime increase of 25 %
Siemens AG Service Operating Vessels (SOV) Depends on site; for an example see text
Siemens Energy Management Division Offshore Transmission Module (OTM) CAPEX cost reduction up to 40 %
Siemens Wind Power and Renewables Division SWT-7.0-154 wind turbine AEP is increased by 10 % compared to predecessor
The Switch Advanced drive train packages based on permanent magnet technology n/a
Universal Foundation A/S Mono Bucket Foundation 7 to 10 % reduction on LCOE equal to a CAPEX cost reduction of 25 to 30 %
Weidmüller Interface GmbH “FieldPower Wind Energy” - system solution for tower lighting n/a
Zensor Structural health monitoring 0.8 €/MWh


Similar Entries

The first turbine jacket foundation is installed at the Seagreen Wind Farm site, 27 kilometres off the coast of the county of Angus in Scotland (pict: SSE Renewables)

The first turbine jacket foundation has been installed at Seagreen – Scotland’s largest and the world’s deepest, fixed bottom offshore wind farm.

Wind turbine (pict. Dewesoft d.o.o.)

The energy company Vattenfall has selected Dewesoft to provide the tower monitoring solution at what will be the world’s largest offshore wind farm.

Rostock-based company EEW Special Pipe Constructions GmbH has received an order from the Swedish energy group Vattenfall to produce 41 monopiles for the 344 MW offshore wind
farms Vesterhav. The contract was signed on 19 November 2021.

Strohm and Siemens Gamesa collaborate on offshore green hydrogen solutions (pict. Siemens Gamesa Renewable Energy)

Strohm, the world's first and leading manufacturer of fully bonded, Thermoplastic Composite Pipe (TCP), has signed a memorandum of understanding (MOU) with Siemens Gamesa Renewable Energy, the global market leader in offshore wind.