LEAN AND MEAN OFFSHORE WIND OPERATION Having in-house capabilities creates a pride of ownership that motivates the team Michael Simmelsgaard DONG Energy Today, the field is much different. DONG regularly brings in hardware manufacturers and specialised service providers in key areas like blades and drive trains. It logged just under two million work hours at its project sites last year, Simmelsgaard says, the equivalent of about 1300 workers. That means that even with a base team of 500, the company had to contract out for up to 800 more. “It is more or less a mixture, making sure we have the right guys to do the right things,” he says. “We don’t want to do things where people are better at it in the market.” Having in-house capabilities, though, carries a number of advantages. It creates a pride of ownership that motivates the team and gives the company a deeper understanding of the causes and costs of lost production, says Simmelsgaard. As importantly, it allows DONG Energy to take charge of maintenance planning and scheduling. Owners in control “It gives me the possibility to take the very clear decision on whether to leave the technicians on quayside today because production is too high, or to send them out.” Simmelsgaard says. “It is more difficult to write that into a contract with a subcontractor, to make sure the right balance is struck between production and hours in the turbine and the cost associated with that.” European utility Vattenfall, the world’s second largest offshore wind operator largely thanks to its historical acquisitions in the Danish power system, also takes over O&M on its wind farms once the turbine warranty has expired. “We don’t necessarily do all the maintenance ourselves but we will be in control so that we plan what is going to be done and when to do it,” says Bent Johansen, Vattenfall Wind Power's Danish head of generation. “We think that’s where we are going to create more value.” Although weather is key to every decision on offshore O&M, other factors come into play. It is not just about maximising electricity output, says Johansen, but financial output as well. “When a turbine stops we always evaluate if we should send someone out there right away. That depends very much on the wind forecast, what the electricity prices are right now, and how they will be in the near future,” he says. Vattenfall may also choose to stop turbines in windy periods of oversupply and low prices, Johansen adds, noting that Denmark has seen periods of negative pricing on its electricity market. Reasons for shutting down turbines can be technical, but they can also be driven by market economics, he says. that is monitoring an operating portfolio that will jump to 1.3 GW when the 288 MW DanTysk wind plant off Germany completes commissioning this spring. “That is what helps us with our planning,” says Johansen. Robust data analysis can help operators catch problems before they become faults, plan service so it is not done too early or too late, and make the most effective use of time at the turbine by bundling maintenance tasks. Do as little as possible “Ideally from a cost, but even more from a safety perspective, for us the most important thing is to do as little as possible. If you don’t do anything it doesn’t cost anything and no one gets hurt. That would be the ideal scenario,” says Simmelsgaard. “But when it comes to the point where you actually have to do it, the better prepared you are and the better plan you have, the safer and more efficient it will be.” At a wind farm level only, data analysis can alert operators to single units that may be underperforming compared to the rest of the turbines. Data collected across an entire operating fleet can uncover important patterns or trends, especially when the age of the projects covers a wide range. “I think we definitely believe in fleet-wide analysis, because then you can utilise the learnings from the earlier turbines,” says Simmelsgaard. “I have some oil and gas colleagues who are very envious that I have close to 900 units that I can learn from, all the way from the monopiles to cables to everything in the turbine. And I can bring that knowledge to the next wind park.” Johansen has seen a shift from even just five years ago, when a lot of the industry’s attention was on new project development. “The focus is moving more to operating the existing wind farms," he says. It is where the money comes from in the end.” Data, data and data Making these kinds of strategic decisions requires information and both DONG and Vattenfall have invested heavily in data collection and analysis. Vattenfall has a surveillance centre at Esbjerg on Denmark's west coast Blades built to last With blade tip speeds on offshore wind turbines reaching more than 300 kilometres an hour, even something as seemingly harmless as a collision with a raindrop can be a problem. "If you jump into a pool from a height of just four or five metres, that is already pretty scary. Now try the same at 300 kilometres per hour and do it for 20 years in a row without any maintenance. Imagine what you would look like at the end of it," says Roel Schuring, vice-president of engineering at the Denmark-based blade manufacturer LM Wind Power. The company that has logged over 3000 equivalent blade-years of operating experience at offshore wind parks since 1991, 48 Text Diane Bailey when it supplied blades to the world's first wind turbines offshore, at Vindeby, Denmark. Schuring's analogy points to one of the major challenges for the offshore wind industry when building blades to last. High speed winds and repeated contact with the rain, hail, sand and salt crystals can cause pitting, gouging and delamination along the leading edge of the blade. That can result in costly repairs, changes in aerodynamic performance that risk a drop in annual energy Tough life: At tip speeds of 300 kilometres an hour, even colliding with raindrops can cause problems over time, says LM Wind Power’s Roel Schuring Photo LM Wind Power » Denmark: A United Industry Thinking Big
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