New guidance has been published today by the
Carbon Trust’s Offshore Wind Accelerator (OWA) to give the offshore wind
industry a unified, systematic approach to the risk management of cable
burial for the first time. The Cable Burial Risk Assessment (CBRA) Guidance
offers a standardised, repeatable and qualitative method to improve risk
management of subsea cables for offshore wind farms, improve conservative
estimates of residual risk,
and ultimately reduce the installation and insurance costs for subsea cables.
Cables
are the root cause of the most frequent and largest insurance claims against
offshore wind developments.
According to industry figures shared by
GCube, specialist offshore underwriter,
over 80 per cent of construction projects have resulted in a cable related
incident. Over half of these claims are solely down to
incorrect installation and load out of cables.
Between 2007
and 2014,
the cumulative costs to insurers was £75 million with over 60
incidents alone resulting in pay outs of between £0.5
million and £13.5 million per claim.
The CBRA Guidance provides a risk based assessment and enables the burial
Depth of Lowering specification to be optimised.
In addition,
it provides a means to assess the residual risk to the cable after burial
operations are complete to a specified depth.
Dimitris Kostopoulos, Electrical Systems and Cable Installation Project
Manager,
OWA,
the Carbon Trust,
commented: “The CBRA Guidance will give the industry a new mind-set
rather than simply being a Depth of Lowering calculation method.
The Guidance details a pioneering method to evaluate the real external
threat to cables based on actual site conditions available for all stakeholders.
For the first time CBRA enables the cable protection level to be assessed
once the installation operation is performed through the evaluation of
the residual risk, as well as over time,
by periodically updating the site survey data.”
Truels Kjaer,
Chef Risk Engineer,
Codan Insurance added: “Codan Insurance has been involved in nearly
every offshore project in Europe. Based on this experience we are very
aware of the importance of a well-defined and in detail specified cable
route. Here the burial depth is essential. Not just a general depth but
a depth depending on soil conditions and general activity in the area.
Therefore the CBRA Guidance will to my opinion really give value in planning
and executing offshore cable installation.”
Claus Fridtjof Christensen Lead Principal Specialist, DONG Energy Wind
Power commented: “Risk based assessment is widely used in several
industries as this approach has larger flexibility and can handle the continuous
development and changes that are particularly relevant in the wind industry,
whereas a prescriptive method that although applicable for the situation
it has been developed for, would most likely not be able to handle modifications
or changes in the industry.
The Guidance for cable burial risk assessment methodology is therefore
highly appreciated. Furthermore, as the guidance refers to a lot of background
information and has been developed together with -
and reviewed by the industry, the suggested values and related uncertainties
are aligned with the industry. The CBRA Guidance therefore gives a good
common methodology for the industry and will also ensure that risk assessments
can be compared.”
Leon Eliassen Notkevich,
Head of Electrical Systems, Statkraft Wind Offshore commented: “The
CBRA Guidance provides the industry with a long sought after methodology
for striking the right balance between the need to protect cables from
external threats and at the same time minimise cost and risk of damage
during installation.
Furthermore, the guidance introduces a common glossary,
a useful discussion of the main contributors to cable damage and a comprehensible
approach for targeting a reasonable depth of lowering along the cable route.
Finally, the guidance provides a means of determining the residual risk
of cable damage for the as laid asset. This is extremely useful for underpinning
system availability calculations and engaging in dialogues with stakeholders
such as financiers, OFTOs and insurance companies.”
The first generation of offshore wind farms have seen significant cost
overruns and delays. A review of the insurance claims indicates that issues
with cabling have been disproportionate to their capital cost and are the
root cause of the most frequent and largest claims. Minimising the specified
depth of lowering and therefore, reducing cable handling and maximising
the number of tools capable of trenching the cables is considered one method
of reducing these problems.
To date,
the absence of a suitable method of assessing risk management in cable
burial has led to a proliferation of approaches developed individually
by developers. The Burial Protection Index (BPI),which was originally developed
for fibre optic communication cables in the 1990’s
has been widely applied to the first generation offshore wind farms. However
the BPI has limitations and as a result is no longer widely used. The purpose
of the CBRA Guidance is to present a new Cable Burial Risk Assessment
method which advances the BPI method.
In addition to the impact on project
financing, increased understanding of the risks will help to open up assets
market as it introduces more options for suitable solutions.
Please see the full CBRA Guidance here
http://www.carbontrust.com/media/622265/carbon-burial-
risk-assessment-guidance.pdf.
The OWA is a joint industry project involving nine developers representing
roughly three-quarters
of the UK’s licenced capacity – DONG Energy,
E.ON,
Mainstream Renewable Power,
RWE Innogy,
Scottish Power Renewables, SSE Renewables, Statkraft, Statoil and Vattenfall.
The developers in the OWA are of the consistent opinion significant cost
savings can be made by optimising the specified cable depth of lowering
by using the developed CBRA Guidance.
About the Carbon Trust
Carbon Trust is an independent company with a mission to accelerate the
move to a sustainable, low carbon economy. The Carbon Trust: advises
businesses, governments and the public sector on opportunities in a sustainable,
low carbon world; measures and certifies the environmental footprint of
organisations, products and services,
and helps develop and deploy low carbon technologies and solutions, from
energy efficiency to renewable power.