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Standards already exist for several renewable energy technologies, including wind turbines and photovoltaic (PV) cells. But currently there are few dedicated standards for marine energy systems. Consequently, technology developers are exploring how standards that exist in other industry sectors can be applied to their designs – a pragmatic approach to make best use of available knowledge.
Due to similarities in their operating environments, standards for the offshore oil/gas and shipping sectors are particularly relevant to marine energy systems. However, it is generally not obvious which particular standards are most appropriate, or to what extent the advice contained within the standards is directly applicable to marine energy systems. Expert help is needed to overcome these barriers.
The Carbon Trust/DNV guidelines for wave energy devices
In recognition of this, the Carbon Trust asked Det Norske Veritas (DNV) to prepare a set of guidelines on the application of existing offshore standards to marine energy systems. This is available to download free of charge, both from the Carbon Trust (pdf, 1.4MB). and the DNV website
The guidelines:
- Focus on wave energy devices, but certain parts are also relevant to tidal stream energy devices; and
- Are intended principally as an aid to technology developers, but may also be of interest to other industry stakeholders (e.g. insurers)
Key points about the guidelines
- The guidelines do not in themselves represent new technical standards. Rather, they are a set of ‘signposts’ to existing standards, with guidance on why and how these may be useful. The guidelines may be regarded as a precursor to dedicated standards for marine renewables, while these are unavailable;
- The purpose of the guidelines is not to enforce existing standards on technology developers. This would be misguided, since wave energy systems differ to other systems in many important aspects. (For example, compared to offshore oil/gas platforms, wave energy devices are unmanned and do not contain/convey large quantities of hydrocarbons.) Rather, the purpose is to see what knowledge already exists in other industries and where it may be appropriate and advantageous to use it; and
- Due to the many options available in the design of wave energy devices, it is a challenge to create guidelines that are applicable to all types of device. Nevertheless, the guidelines have been developed with the intention of being ‘product-blind’, without favour to any particular device type.
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Approach and contents of the guidelines
The guidelines recognise that a wave energy device design will do a combination of the following options:
a) Use novel technology;
b) Use existing technology in a novel setting; and/or
c) Use existing technology in a conventional setting.
As might be expected, option c) is generally most amenable to the application of existing standards. Options a) and b) will require some interpretation, and may be best approached by a process of technology assessment called ‘Qualification of new/unproven technology’. DNV define this as ‘The process of providing the evidence that the technology will function reliably within specific limits’, and involves a mixture of technical analysis and studies, technical risks and reliability assessments, laboratory testing and prototyping.’ The first part of the guidelines explains Qualification further.
The guidelines then go on to cover major generic, and indeed some quite specialised, component technologies and systems that a wave energy device may use. A complete list of the systems, components and engineering disciplines covered in the guidelines can be seen in the Guidelines’ contents list and is also shown below:
Main document:
- Qualification of new and unproven technology
- Failure mode identification and risk ranking
- Value management and life cycle analysis
- Reliability and cost
- Risk assessment
- Safety philosophy
- Documentation
- Material selection
- Corrosion protection
- Structural design criteria
- Foundation design
- Mooring system analysis
- Stability and watertight integrity |
- Electrical and mechanical equipment
- Fire protection
- Instrumentation and control systems
- Umbilical connections
- Cable connection to shore
- Manufacturing
- Installation and retrieval, temporary phases
- Commissioning and handover
- In-service phase – operations and maintenance
- Decommissioning
- Statutory regulations |
Appendices:
- Fatigue analysis methodology
- Wave modelling and loads
- Technical considerations for air flow turbines
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- Technical considerations for gearboxes
- Inspection
- Relevant electrical and mechanical items
- Steel grade conversion |
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