The number of available maintenance vessels needs to increase rapidly to keep up with offshore wind development

By Sam Phipps
 
Utilities and contractors involved in both wind farms and tidal/wave power projects admit more purpose-built boats for operations and maintenance (O&M) are needed in the coming years.

Colin Morgan, offshore director at Garrad Hassan, a consultancy based in Bristol, explains that two basic types of vessel are used for O&M: smaller boats for taking mechanics to and from wind farms, for instance for routine inspections or light repairs, and huge crane vessels for removing heavy components such as gearboxes.

At the moment these crane vessels tend to be the same kind that are used in the construction and installation of offshore turbines, which means they are often bigger and more cumbersome than is ideal. Plus availability of these vessels is currently low and new boats are expensive to build.

“The lighter boats can be hired and built pretty easily, and at no great cost. They’re usually fast catamarans. But construction vessels are more of an issue,” says Morgan. “They can be in short supply. When there’s slack in the [offshore] oil and gas industry, their vessels can be redeployed for offshore wind, but the day rates are high, so it’s expensive.”

“There are only around 10 jack-up crane vessels working the offshore wind business, which is basically all centred in Northern Europe at present,” Morgan says. “Depending on specification, the build cost for each one will be £50m to £200m.”

Vessel build up

It takes two to three years to build a jack-up vessel, which Morgan says is conveniently similar to the lead time for an offshore wind farm. He forecasts supply of the vessels to rise accordingly. “The number of these vessels needs to double in the next five years, which is entirely feasible. It needs to double again two to three years after that,” he replies.

The main providers of offshore wind maintenance vessels include A2SEA, MPI and SMIT. MPI Offshore, based in Yorkshire, UK, currently run one offshore O&M boat and are building two more vessels to keep up with demand. The two new MPI boats, ‘Adventure’ and ‘Discovery’, represent an investment of $550 million and are due for delivery and commissioning in the first and third quarters of 2011.

Current bottlenecks

David Surplus, managing director of B9 Energy Services – which provides O&M for onshore and offshore wind farms in the UK, Ireland, the US and Canada admits that bottlenecks sometimes occur, particularly during summer, the time of highest demand for maintenance barges because weather conditions are generally most favourable. But he explains this would not deter investors or utilities from committing to an offshore project.

Surplus expects today’s construction vessels will be too small for installing Round 2 and 3 wind farms over the next 10 years. They will be superseded by bigger craft and can therefore be adapted purely for maintenance work on the Round 1 wind farms that are now being developed or are already operational.
Likewise Chris Smith, an offshore specialist at E.ON, says the relative scarcity of appropriate vessels reflects the fact that offshore renewables are a fledgling industry, “with a limited number of players and vessels”.

“What we need is vessels perfectly designed for offshore maintenance. Some very large ones are used to install wind farms but if you need to change a gearbox [on a turbine] that vessel might not be ideal,” says Smith.

He expects tailor-made maintenance vessels to become widespread in the next five years.

One company that is reported to be developing specialised equipment of this kind is Germany’s Bard Engineering, which has already introduced its own 5MW 280 tonne turbine for use in rough offshore seas. By next year it is planning to have 80 of these turbines operational on one site, the “Bard Offshore 1 Wind Farm”, which  – where is this?