Operations and maintenance in offshore wind:
key issues for 2015/16
Mike Newman
September 2015
TLI-KI-00001
With more than 5GW installed offshore wind capacity in the UK, comprising more than 1300
turbines – and the ambition to increase this capacity to 10GW by 2020 – there is a growing
market for operations and maintenance (O&M) products and services.
These products and services need to target a reduction in the levelised cost of energy (LCoE),
optimise energy yield or reduce the need for unnecessary access to larger turbines in deeper
water, further from shore. In addition, there are major opportunities for the UK to build on its existing
strengths and experience to deliver exportable products and services into the global offshore wind
O&M market.
This paper outlines the key industry issues that new O&M products and services need to address in
order to deliver into the offshore wind market.
Topic description
To remain competitive, offshore wind O&M products and services will need to focus on increasing
reliability and availability to optimise energy production and decrease LCoE.
Technology solutions that target increased reliability of main components should also focus on
reducing the need for site access. This will become more important as offshore wind farms come out
of the warranty period and asset owners look for alternative O&M solutions. ORE Catapult estimates
that, by 2020, around 2,700 offshore structures across Europe will be outside of their initial warranty
period.
Changes in O&M procedures due to end-of-warranty decisions will widen the opportunity for third party
O&M providers to enter the market. This presents opportunities for UK companies to grow
expertise and experience in their national market for future export of O&M products and services
worldwide.
The Offshore Wind Cost Reduction Pathways: Technology Workstream by BVG Associates (2012) for
The Crown Estate was completed for baseline wind farms containing a range of 4-10MW turbines. The
study found that unscheduled activity – which can either be reactive, in the case of a fault, or proactive, if a crew happens to be on site – constitutes around 65% of O&M costs in each of the site types
modelled. This high proportion (roughly two thirds) of unscheduled maintenance would not be acceptable in other more mature engineering industries such as aerospace or thermal power
generation.
A shift towards decreasing the proportion of unscheduled to scheduled maintenance activities would
signal a more mature and stable offshore wind industry. This transition to an increasingly planned
schedule of maintenance could be facilitated through the development of new O&M strategies,
innovations and technologies.
The Pathways study also outlined key innovations that can drive a reduction in LCoE by a potential
2.4% in offshore wind farms that reach final investment decision (FID) by 2020. This included
innovations across condition-based maintenance, access and personnel transfer, inventory
management and weather forecasting.
ORE Catapult’s recent Cost Reduction Monitoring Framework summary report (ORE Catapult, 2015)
confirmed that many of the innovations identified in the Pathways study are on target or ahead of
target for delivery by 2020. However, a great deal of work remains to de-risk these technologies to
ensure greater market penetration for new and existing wind farm sites.
There are a number of additional O&M technologies not covered in detail in the Pathways and CRMF
reports that could also have an impact on LCoE by 2020.
ORE Catapult categorises the industry’s priorities for further offshore wind O&M technology development as follows:
•
Improvements in asset management strategies such as improved decision making tools for
onshore-based versus offshore-based logistics strategies and new methodologies for
condition-based maintenance
•
Improvements in asset management tools such as condition monitoring systems, O&M cost models and logistics planning tools
•
Developing new offshore logistics concepts such as vessel concepts, access systems and remote access
•
Reliability improvement such as shared learning around root cause analyses of failed components and sharing of reliability data
•
Standardisation and sharing of knowledge such as standardised boat landing connectors and standardisation of operational key performance indicators
ORE Catapult definition of O&M
Offshore wind O&M includes all onshore and offshore activities between the periods of
commissioning and decommissioning of a turbine that are required for the management and
maintenance of the project.
Operations includes the day-to-day activities that cover the high level control and management of the
wind farm such as remote monitoring, contracting of port facility, crew transfer vessel hire and
electricity sales.
Maintenance includes the repair and service of the wind farm and is split into scheduled preventative
maintenance and unscheduled corrective maintenance.
This paper covers key issues that are encompassed within the above definition of O&M. However,
there are certain issues related to the O&M of key components that are not explored in detail. For
example, blade erosion is a key issue for the sector but will be expanded upon in other ORE Catapult
Knowledge Area Key Issues documents.
O&M’s share of LCoE
The estimated OPEX for a typical offshore wind turbine ranges from £60,000 / MW/year (E&Y, 2009)
to £87,500 /MW/year (BVG Associates, 2012).These figures do not include leases paid to The Crown
Estate (TCE), Transmission Network Use of System (TNUoS) charges or operational insurance
premiums.
Although there is a lack of hard data in the public domain for offshore wind OPEX, sources suggest
that the contribution of O&M to the LCoE of an offshore wind farm may be as high as 25% (Hassan,
2013).
Other high level analyses show OPEX (including TNUos and operating insurance) consistently
exceeds 20% of the LCoE across four different modelled site types (BVG Associates, 2012). In-house
ORE Catapult analysis shows O&M contributing 15% to LCoE when TNUos and operating insurance
are excluded.
There is significant variation in stated O&M costs, because no offshore wind farm in the UK has
reached the end of its life – the oldest offshore wind farms are only just passing the halfway point of
their expected 25-year lifecycle. As such, a measurement of full offshore wind O&M costs is not yet
possible.
Key issues
How will the sector reduce the cost incurred by unexpected component failure and subsequent
corrective maintenance activities?
Previous generations of offshore wind farms had relatively small amounts of monitoring equipment,
due to prohibitive costs of installation.
The data that is gathered from this equipment has, historically, rarely been used by the operator in the
most efficient way. A lack of effective interpretation of this data can lead to reactive O&M activity, which
can be costly for the asset owner.
For next generation turbines, there is a recognised need for advanced condition monitoring solutions
and smart use of the data already generated by wind farm systems. This will allow asset owners to
understand when components are likely to fail, thereby reducing the need for unscheduled
maintenance interventions.
Planned research
A better understanding of the differences in component-based reliability for offshore assets, similar to
that achieved for onshore wind farms, is required. ORE Catapult’s database for System Performance,
Availability and Reliability Trend Analysis (SPARTA) is addressing this challenge by collecting reliability
data from offshore wind farms on a monthly basis and developing one of the industry’s most robust
databases for offshore wind farm performance. ORE Catapult will work with operators to identify
upcoming key issues by analysing existing data, enabling early solutions development.
Condition-based maintenance (CBM) methodologies are widely applied in other industries such as
aerospace and thermal power generation, but less so in offshore wind. ORE Catapult is currently
working on the demonstration of methods and tools for the optimisation of operational reliability of
large-scale wind turbines through its involvement in Project OPTIMUS, an EU FP7 funded project that
seeks transfer of best practice from other sectors.
The project has delivered useful early stage results about the failure modes that affect wind turbines.
This work will continue until 2017, alongside the launch of further ORE Catapult innovation challenge
statements that aim to create opportunities for technology companies that develop condition
monitoring systems for the sector.
ORE Catapult will seek to de-risk these technologies through the use of its testing and demonstration
assets in Blyth, as well as ensuring the involvement of key UK academic capabilities.
How will the sector optimise O&M strategies in further from shore and deeper water sites that
experience higher sea states and are no longer accessible by way of onshore-based O&M strategies?
Onshore-based O&M strategies (where crews are based onshore) have, to date, been used to
maintain nearshore wind farms. As sites are developed further from shore, there is a move to offshorebased maintenance, where large offshore support vessels (OSVs) are based offshore for weeks at a
time. Within this shift there is likely to be a number of hybrid strategies: onshore-based strategies with
helicopter support; quasi-offshore based strategies; and fully offshore-based strategies.
Decisions regarding effective O&M strategies are made during the early stages of planning a wind
farm. As such, decisions made throughout the wind farm lifecycle need to be informed by higher
quality data, O&M models, tools and systems. This is a key issue also highlighted in the European
Strategic Research Agenda (TP Wind, 2014).
Planned research
Bespoke next generation Crew Transfer Vessels (CTVs) are being developed with a view to reducing
weight and manufacturing costs, while increasing the standard of crew accommodation.
This will stretch the capability of CTVs and potentially extend the distance from shore to which
onshore-based O&M strategies are implemented. In addition, bespoke OSVs are beginning to enter
the market and early commercial deployment will yield useful information about their actual
performance compared to initial projections.
Further testing and validation of these next generation designs at scale will be crucial for further
development: ORE Catapult will continue to support access to demonstration infrastructure through
testing facilities at Blyth and our online directory of additional UK Renewable Energy Facilities.
ORE Catapult aims to support access to data to help validate new and existing O&M models and
logistics planning tools. These tools will also begin to incorporate new data sources, such as satellite
data and higher resolution environmental and metocean data. Tools will be more intelligently
integrated with other systems that are currently run separately as and when maintenance takes place.
How will the sector increase access windows and reduce wastage of technician time due to
weather delays?
The sector is faced with uncertainty around the predicted available weather windows for timely
access to an offshore asset. Inability to access the wind farm due to uncertainty in weather windows
can cause delays to necessary maintenance that is prohibiting full operation of the wind farm.
Development is continuing on site-specific weather forecasting models that will provide more certainty
around five-10 day forecasting.
Accuracy in longer term predictions (up to 21 days) could also decrease LCoE by an average of
around 0.2% (BVG Associates, 2012). ORE Catapult believe that this decrease could be greater still if
it has significant impact on campaigns that involve jack-up operations, specifically. Crucially, we should
ensure that the information presented by weather information systems enables optimal decision
making.
There has also been development of improved access systems that can work in higher sea states,
which can widen access windows. A number of companies have developed dynamic access systems,
but not all of these systems will be compatible with smaller CTVs for use on wind farms closer to
shore. Work is likely to continue on providing alternative solutions that can be used in combination with
smaller, more dynamic CTVs.
Planned research
To date, demonstration of access systems at sea has been crucial to enable validation of the
technology. ORE Catapult will seek to facilitate access to offshore assets for companies to further
demonstrate the next generation access systems.
To increase efficiency in decision making processes when organising access to the offshore wind farm
and planning vessel hire, the accuracy of weather forecasting models will need to increase. Although
there has been significant improvements in the five-10 day timeframe, further improvements are
needed as well as more accurate 21-day forecasts for longer term campaign planning. This will enable
optimisation of marine logistics and provide opportunities for planning campaigns in low wind speed
periods, to help optimise yield. ORE Catapult will act as coordinator in this space and work with key
academic and industry partners to ensure that site-specific weather forecasting models are developed
to specific industry user requirements.
How will we optimise yield, while minimising damage to components on large arrays?
Wind turbine control is currently undertaken on a turbine-by-turbine basis to achieve the optimal
performance of that turbine. There are, however, factors that act at the wind farm scale, such as grid
curtailment requests, wake propagation and variation in asset health. At present, turbine control
systems do not take these cumulative impacts into account, potentially resulting in main component
failure when individual turbines experience conditions that are beyond their expected design life.
Some commercial offshore wind farms are beginning to move towards fully integrated systems, with a
controller that uses condition monitoring and Supervisory Control and Data Acquisition (SCADA) data
from all turbines and environmental site data to continuously update the operating state of each
turbine. This enables more flexible control at a wind farm level, optimising performance across all
turbines to meet the objective of increasing the life of wind turbine components while optimising
energy production.
At present, there is a lack of incentive for turbine manufacturers to introduce whole wind farm control
systems that take into account different factors affecting the asset at a wind farm level. A move
towards yield-based warranties may facilitate that development, providing an incentive for turbine
manufacturers to improve yield, rather than optimising the wind farm solely on an availability target.
Planned research
ORE Catapult seeks to work with key technology companies that are developing whole wind farm
control systems to support validation of their innovations through access to necessary operational and
environmental datasets and to operational assets.
We will also integrate this work into activity in our Wind and Ocean Conditions Knowledge Area on
wake measurement and modelling. By doing so, we will ensure that our learning around the effects
of atmospheric phenomena, such as instability, are incorporated into the assumptions and inputs of
these control systems.
How will the sector increase its collective understanding of the reliability of key components to
improve future designs and drive greater efficiency in O&M campaigns?
While improving offshore access for technicians is required, innovation should focus on reducing the
number of interventions required and minimising the vessel transfers necessary to operate a site.
Reliability-centred maintenance will ensure plant reliability is maximised and unplanned interventions
are minimised. An industry-wide understanding of the reliability of offshore wind subsystems will help
to identify where innovation is required. This will drive operational improvement and impact future
offshore wind system designs.
Planned research
Databases for recording failure data across multiple offshore wind farm assets will be developed,
amalgamating root cause datasets from operators and laboratories. For this reliability data to be of
use, it must be relevant to the systems and consistent across the sample. Existing methodologies,
such as those developed for the EU FP7-funded Reliawind (CORDIS, 2010) project that focussed on
onshore turbines, could be adopted to begin to understand the downtime associated with subsystem
failures of offshore wind turbines.
ORE Catapult’s SPARTA project provides accurate reliability data for the UK offshore wind sector
through sector-wide collaboration and a strong focus on data quality and consistency. Every operator
with offshore wind farms in UK waters participates in the SPARTA system, providing performance and
failure data from more than 50% of installed capacity on a monthly basis.
Some organisations are making progress with the development of more detailed reliability databases
such as the Danish database for blades at Offshoreenergy.dk and WMEP – also known as WindPool – at Fraunhofer IWES in Germany. There is, however, room for further development of reliability
databases that contain qualitative information about component level failures, such as downtime and
associated repair activity.
Specific issues that threaten reliability of key components must also be addressed and ORE Catapult
will work in these areas where it is appropriate. For example, the Blade Leading Edge Erosion Programme (BLEEP) has been set up to overcome issues with reliability and blade performance and will
be delivered by our Blades Knowledge Area.
How will the industry improve information sharing in O&M?
Typically, when an offshore wind farm is under warranty, contractual arrangements mean that project
developers are left without access to critical information to help build expertise in how to efficiently
operate and maintain the offshore assets. The impact of this is felt in particular by the developer, when
maintenance responsibility is handed over at the end of a warranty period.
Information in relation to the reliability of offshore wind farms is not standardised at present. For
example, there is no industry-accepted definition of failure or designation system for the nomenclature
of subsystems and components.
Planned research
Standardisation of critical KPIs, such as availability and energy-based curtailment, will provide
offshore renewable energy project developers with the information required to understand how the
asset is performing and to identify the sources of downtime.
The work on SPARTA has driven standardisation of KPI data in offshore wind, which is crucial for
enabling greater collaboration and transparency for cross-sector comparisons. SPARTA is aligned with
the IEC 61400-26 series for measuring wind farm availability and has adopted the RDS-PP taxonomy
for wind farm subsystem components. Furthermore, ORE Catapult is working with IEA Task 33 to
standardise data inputs, statistical analysis and O&M tools used in the wind power industry.
There is also a need for a more coordinated industry approach to managing component-level asset
integrity data across different components within a wind farm. In addition, there is a need to
standardise the terminology used to characterise asset integrity and a robust monitoring process to
maintain the usefulness of the data.
ORE Catapult will achieve this coordinated approach to asset integrity data sharing via an
anonymised database. It will identify key issues through data analysis and work to provide solutions
for those that partake in the process. We intend to start this process by developing a segment of this
database, focused on cables.
How will we accelerate development of subsea monitoring technologies to meet market
demand?
Subsea monitoring covers a wide range of technologies and methods. It includes activities such as
sending divers or Underwater Autonomous Vehicles (UAVs) to inspect foundations visually or using
condition monitoring systems to provide feedback on subsea component integrity. Bathymetric
surveying is also completed throughout the lifecycle of an offshore wind farm, including the O&M
phase to monitor for issues such as cable scour.
While there is a routine need for subsea monitoring methods, it is also sometimes required for
unplanned events during O&M. This can be a costly process due to insufficient supply of optimised
technologies or processes for the job at hand. Development of subsea monitoring technologies that
are either designed specifically for or are matched to the requirements of the offshore wind industry
is a priority for the sector. In many cases, key subsea monitoring technologies are already utilised in
other sectors and there is limited research and development that needs to take place in order for them
to reach commercialisation in the offshore wind sector.
Planned research
UAVs will play an increasingly important role in the inspection of subsea infrastructure, for checking
the integrity of components such as cables and foundations. ORE Catapult will seek to work with companies that are developing cost-efficient technologies that meet the needs of offshore wind and will
provide testing and demonstration space to de-risk the new technologies.
ORE Catapult has also identified an opportunity for more cost-effective bathymetric data collection
methods by working to introduce those used in the maritime sector. This could involve fitting data loggers to routine maintenance vessels to enable crowdsourcing of their sonar data or combining existing
datasets with satellite-derived bathymetric information about a site.
How will we know when it becomes economically feasible to repower or extend the life of an
offshore wind farm asset?
The oldest offshore wind farms in UK waters and internationally are only now passing the midway
point of the planned 20-25 year lifecycle. Consequently, operators are beginning to explore whether it
is economically viable to extend the life of their assets or repower a site.
The decision to extend the life of a wind farm is site-specific and depends on a variety of issues, particularly the structural integrity of the balance of plant infrastructure. The speed of turbine technology
development over the next five-10 years will also have a bearing on whether decisions are taken to
re-power existing infrastructure with turbines of a higher power output.
Planned research
ORE Catapult intends to work with key universities and companies to draw in international state-ofthe-art academic and industry thinking around reliability of key components. The aim will be to develop
a programme of activity including collection of key condition monitoring and asset integrity datasets
that will lead to development of models for component lifetime prediction and O&M. This may also
lead to development of new materials or repair methods for extending the life of wind farm components.
The programme will link to other key research and development projects that are delivering related
monitoring and modelling outputs, for example, work being undertaken in the Structural Lifecycle
Industry Collaboration (SLIC) and BLEEP.
New knowledge in this space will also feed into industry standards bodies for the development of new
standards for products with extended lifetimes.
Throughout this programme, we would seek collaboration from other sectors for lessons learned on
how extended life modelling and repair methods have been delivered elsewhere. The programme will
enable operators to make informed technical decisions about extending the life of their asset.
Recommended reading
Offshore industrial strategy: Business and Government Action, Department of Business, Innovation
and Skills, August 2013, available online at https://www.gov.uk/government/uploads/system/uploads/
attachment_data/file/243987/bis-13-1092-offshore-wind-industrial-strategy.pdf
Pathways to Cost Reduction in Offshore Wind Technology: Technology workstream, BVG Associates
June 2012, available online at http://www.bvgassociates.co.uk/Publications/BVGAssociatespublications.aspx
UK Supply Chain Capabilities for Offshore Wind, BVG Associates, 2014, available online at http://
www.bvgassociates.co.uk/Publications/BVGAssociatespublications.aspx
RELIAWIND Report Summary, CORDIS, January 2010, available online at http://cordis.europa.eu/result/rcn/55560_en.html
ECOWindS Patent summary for regions, ECOWindS, 2014
Cost of and financial support for offshore wind, Ernst&Young on behalf of the Department for Energy
and Climate Change, April 2009, available online at http://webarchive.nationalarchives.gov.uk/+/http:/
www.berr.gov.uk/files/file51142.pdf
Condition Monitoring – Key Findings of a holistic approach to wind turbine monitoring report, the
Energy Technologies Institute, 2014, available online at http://www.eti.co.uk/condition-monitoring-keyfindings-of-a-holistic-approach-to-wind-turbine-monitoring-report/
Y Feng, P Tavner and H Long, ‘Early experiences with UK round 1 offshore wind farms’, Proceedings
of the Institution of Civil Engineers (2010)
H Government, Offshore Wind Industrial Strategy (2013)
G Hassan, A Guide to Offshore Wind Operations and Maintenance (2013)
red7marine carrying out repair and maintenance work at London array, Offshorewind.biz, May 29
2014, May 29, available online at http://www.offshorewind.biz/2014/05/29/red7marine-carrying-outrepair-and-maintenance-work-at-london-array/
Generating Energy and Prosperity, ORE Catapult on behalf of the Technology Strategy Board, 2014,
available online at https://ore.catapult.org.uk/documents/10619/116053/pdf/15b55f52-5a1f-4e5a-aa32ee0dba297bce
H&S Guidlines: Offshore Wind and Marine Energy H&S Guidelines (pp 61-73), RenewableUK, 2013,
available online at http://www.renewableuk.com/en/publications/index.cfm/2013-03-13-hs-guidelinesoffshore-wind-marine-energy
Recommended reading (cont.)
Jack-up vessel optimisation: improving offshore wind performance through better use of jack-up vessels in the operations and maintenance phase, The Crown Estate, 2014, available online at http://
www.thecrownestate.co.uk/media/370242/ei-jack-up-vessel-optimisation.pdf
Strategic Research Agenda / Market Deployment Strategy (SRA/MDS), European Wind Energy Technology Platform, 2014, available online at http://www.windplatform.eu/fileadmin/ewetp_docs/Documents/reports/TPWind_SRA.pdf
Author profile
As Innovation Manager within the ORE Catapult Strategy team, Mike
Newman works on the identification, development and delivery of R&D projects and programmes in the offshore renewable energy sectors.
He developed the Operations and Maintenance (O&M) research strategy and supported development of the Wind and Ocean Conditions strategy for the ORE Catapult.
This involved coordinating R&D project development activities across a multifunctional team and delivering technology roadmaps for the sector.
Previously at BVG Associates, Mike undertook offshore wind supply chain and technology innovation
projects. Mike advised cross-sector companies on entering the offshore wind market. These companies ranged from high-technology start-ups to established larger manufacturers and were predominantly delivering into the metal fabrication and O&M supply chains. Mike also supported development
of turbine manufacturer R&D strategy by creating R&D roadmaps, generating a European demonstration site database and undertaking R&D partner scoping.
Disclaimer
While the information contained in this report has been prepared and collated in good faith, ORE Catapult makes no
representation or warranty (express or implied) as to the accuracy or completeness of the information contained herein nor
shall be liable for any loss or damage resultant from reliance on same.
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