Offshore Wind O&M

Jack-up Vessel Optimisation Report

Establishing a safe foundation is a vital part of jack-up operations. The jack-up vessel needs to be supported by an absolutely solid foundation during the entire jack-up operation at any given site.

Jack-up vessels can help bring down costs in the maintenance of offshore wind turbines. The report, ‘Jack-up vessel optimisation’, studies the significant potential in cost reduction through sharing arrangements and closer cooperation between windfarm owners. It points to evidence of significant production downtime due to maintenance planning and implementation and claims that revenues could be increased by as much as GBP 110 million across currently operational windfarms in the UK.

Even though the report is based on the UK offshore wind market, it is valuable reading for the industry as a whole, particularly within a wider European perspective. Operations and maintenance in offshore wind is still an underdeveloped market and this report makes a welcome contribution to improving the market’s understanding of the key issues. This report also sheds new light on some of the findings in an O&M report commissioned by us, in particular related to the sometimes insurmountable costs of emergency repairs to single wind turbines.

Game changer

Accommodation vessels are changing the game. With the range of options available, including floating hotels, accommodation jack-ups and Service Operation Vessels (SOVs), it can be unclear which is the best option. SOVs seem to be the preferred option today, but they may not offer the comfort of the jack-ups, which could be necessary to attract and retain the best technicians. Valuable time can be gained by ensuring that the optimal accommodation solution is included within the O&M planning.

With the huge savings in outage costs a definite motivating factor, there are key decisions to be made. The challenge is surmountable, but it needs more openness and collaboration among key industry players to make it a reality.

Two phenomena to avoid

Punch-through is a phenomenon that occurs when a leg of a jack-up vessel breaks through the seabed. Fortunately, it is a rare occurrence in offshore wind, but there have been catastrophic occurrences within oil and gas. It’s important to do everything possible to mitigate the risk. If the risk cannot be mitigated, then jacking up should not be attempted.

Jack-ups can also be subjected to sliding, particularly if the seabed is very hard and cannot be penetrated sufficiently by the spudcans. Strong lateral forces caused by wind and sea currents can also contribute to sliding. Avoiding these situations involves considering seabed conditions at the jack-up site and the specific characteristics of the jack-up vessel.

O&M Framework Agreements

The report points out the benefits of increased cooperation among operators who are willing to share service jack-up vessels across clusters of wind farms. In addition, more efficient planning will ensure that equipment and tools are available for use by the O&M vessel.

How realistic is a 48-hour major component replacement?

To start with, securing a vessel sharing or framework agreement with your jack-up provider plays an important part. This ensures that contractual terms and conditions are in place before maintenance work is required, which reduces outage days from the outset.

This is a view making waves at both utilities and OEMs. Partnerships and framework agreements will help drive down levelised costs of energy (LCOE). Framework agreements are seen as a natural step and has recently entered into such an agreement for offshore wind O&M services with DBB Jack-Up.

The right equipment for the job

The most sure way to achieve effective preparations is to use equipment specifically suited to the jack-up operation and the site itself. This means using a jack-up vessel that does not require extensive seabed penetration. On some specialised jack-up vessels, the spudcans can be reconfigured to suit the site. If necessary, they can be removed if it’s not necessary to use them or they or not suitable for use at the particular site.