Offshore wind farm operators could be facing O&M costs as high as €100,000 to €300,000 per year, per turbine, according to the latest Wind Energy Update Operations and Maintenance report. This figure could be spiked by an additional 20 percent over the short term, as innovative 5MW variable-speed and direct-drive designs enter the market.
Unknown component failure rates, unknown logistic equipment costs, weather windows dependent on deployment site, and a general lack of understanding on O&M cost correlation to shore distance are just a handful of factors conspiring against offshore operations and maintenance budgets.
So where are the trouble spots and how could these best be addressed?
A key factor determining the availability of an offshore wind turbine is accessibility, says the report. Governed by sea state, season and corresponding weather and daylight hours, “reduced accessibility will result in reduced availability, prolongs downtime, and reduces throughput as well as income generation,” note the report’s authors.
Another major factor determining optimal operation and maintenance is the number and layout of the offshore wind turbines. “The wake effect of the turbines increases turbulence, resulting in higher incidence of damage to the turbine components,” says the report.
Yet another element to consider - and one that is creating a headache for Round Three developers - is distance to shore. The further away from the coast, the larger the weather-window must be to successfully complete a servicing activity. In this respect, the further from the shore, the lower the probability of being able to address a shutdown promptly.
“The further away the park is from the coast, the higher the expected wind speeds, and the larger the significant wave heights,” explain the authors. “With less favorable environmental conditions comes reduced accessibility as well as greater means of access and costs for maintaining high wind park availability.”
So what are the options?
Avoiding failures altogether is clearly the best way to limit O&M costs. While this may seem a far off reality the report predicts that, as the wind industry consolidates and improves design and quality controls in its supply chain, today’s high failures rates will level off and then decline.
In the meantime however, operators must figure out how to get from A to B. The best policy, says the report, is to adopt a preventative maintenance approach.
The report identifies that currently 66 percent of offshore O&M costs are caused by corrective maintenance. Adding salt to the wound, losses of revenue owing to turbine unavailability are of equal magnitude as the costs for corrective maintenance.