[June 2007] Kevin Cleminson, of systems engineering consultancy Frazer-Nash, discusses crucial work that has recently been completed on one of the leading marine renewable technologies – and casts an eye into the sector’s future.

It is widely acknowledged that development in the marine renewable technologies field over recent years has been brisk. And with wave and tidal power projects having the potential for making a significant contribution to the UK’s future energy needs, the sector shows a great deal of promise.

But there are two factors which are pivotal to the ongoing success of renewable energy – reliability and maintainability. The marine renewable devices currently in development might be technologically advanced, but in order to be successfully deployed and commercially successful over the longer term, such devices must meet critical levels of reliability and maintainability.

The Example of Pelamis

Systems engineering consultancy Frazer-Nash is leading work in this area and has been assessing reliability and maintainability on one of the first wave energy machines to be used in a commercial energy farm.

Pelamis is the pioneering wave energy converter developed by the Edinburgh-based company Ocean Power Delivery (OPD), and is due to come into service off the coast of Portugal later this year. And the concept is a unique one – as the tubular elements of the device pass over the surface of the waves, the flexing of the joints between them activate hydraulic rams and generate electricity. Several devices can also be linked together to form ‘wave farms’, and a typical installation occupying a square kilometre of ocean could provide enough electricity for 20,000 homes.

Conventional on-site maintenance strategies can be prohibitively expensive in the offshore environment (especially with the need to transport personnel and equipment to site), but the Pelamis system benefits from being both robust, and easy to repair when trouble strikes.

No on-board personnel, divers or Remote Operated Vehicles (ROVs) are required for connection/disconnection of the Pelamis machine – important not only from a cost perspective but also in terms of health and safety. This strategy maximises accessibility as only relatively short weather windows are required for retrieval operations, compared to maintenance on-site which can require much longer (and statistically less frequent) weather windows.

OPD’s strategy has been to carry out all maintenance activities for Pelamis off-site. The device features a ‘quick connect/disconnect’ mooring attachment system that enables the machine to be brought to a sheltered location such as a quayside for any major maintenance activities.

OPD has spent the past eight years testing and refining the articulated Pelamis converter concept. But in order to ensure that the device is reliable and easily maintained for the future - following its forthcoming deployment - a range of further independent tests were required. Frazer-Nash was approached by OPD because of its reputation as one of the UK’s leading companies for reliability engineering.

The company conducted a detailed modelling analysis to understand just how sensitive the overall reliability of Pelamis was, and to assess the likelihood of components failing – something that could be problematic while the device is in service at sea. This work also allowed OPD to prioritise elements of its maintenance strategy, and further refine it on an ongoing basis.

As a result of Frazer-Nash’s work, OPD has started re-evaluating their existing test data, and have also begun retesting key components – which in turn will enable the company to better forecast its in-service costs, and in the longer term minimise the costs of intervention when maintenance is required.

In addition, the results of the reliability tests will help point the way to further design improvements on the Pelamis system – ensuring it stays at the very front of this energy sector.

Making the Commercial Case

Frazer-Nash’s work on Pelamis demonstrates the importance of reliability and maintainability to the marine renewables industry, and shows how taking these two issues seriously is helping to spearhead development in a promising area of marine renewable energy.

But the wider picture is that the marine renewables sector needs to demonstrate that it can be commercially, as well as technologically, successful. The sector has for a long time been viewed as a high risk one when it comes to securing investment, not least because of the natural challenges that the offshore environment itself presents. As a result, financiers increasingly need to be able to clearly identify the commercial viability of such technologies.

Frazer-Nash has been providing independent technical support to the marine renewable sector for longer than any other engineering services supplier, with nearly all the devices being considered for deployment already subjected to the varying types of operational and engineering analysis the company specialises in.

And what both investors and the technology developers themselves need is impartial information on reliability and maintainability when it comes to a fledgling industry such as this.

Frazer-Nash’s capabilities are such that it can offer financial institutions something which has up until now been largely unavailable – the opportunity for an independent set of eyes to be cast over the marine renewable schemes currently in development, with the probable commercial success of the scheme at its core.

Ian Watson, who is leading Frazer-Nash’s services to banks in the renewable energy sector, said, “The current situation is that banks need to be given the confidence to invest in marine renewable technologies in the first place – and be able to set appropriate terms and repayment levels as a result.  We have been providing due diligence services to the device developers for many years, and have an unparalleled expertise in the challenges of the marine renewable environment. It seemed like a logical progression to make this knowledge available to banks and other financial institutions, now that operational deployment in many cases is becoming more likely.”

Building Confidence

The marine renewables sector is showing great promise, but the industry must now focus on developing technologies that are easily maintained, reliable – and a strong investment.

Developers need the expertise to refine their devices, and to iron out reliability and maintainability issues at the initial design phase. Investors meanwhile need to be given the information that allows them to fully understand the potential of each piece of technology. Focusing on these issues might not be easy, but they are crucial if the marine renewables sector is to realise its true potential.

http://www.fnc.co.uk/

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