Recently, Framo’s pump technology has been used to successfully anchor 20 wind turbines at Ørsted’s new offshore wind farm Borkum Riffgrund 2. With three legs for each jacket, a total of 60 suction buckets were pumped into place to provide foundations for the wind turbines.
For more than half a century, Framo has been a significant provider of pumping systems for the marine industry. Based in Bergen, Norway, Framo is now a part of Alfa Laval’s Marine Division, offering pumping solutions for cargo, oil and gas production and offshore supply and recovery.
Offshore wind farm development has relied heavily on expertise that has been honed first in the maritime industry and later in offshore oil and gas activities. To learn more about how Framo, working together with Norwegian Geotechnical Institute (NGI), has contributed to this aspect of offshore wind’s development, Energy Northern Perspective began an email conversation with Jørgen Brandt Theodorsen, Area Manager, Oil & Gas Pumping Systems at Framo.
Borkum Riffgrund 2 isn’t Framo’s first collaboration with NGI for offshore anchoring and foundation installations, as Theodorsen explains: “Framo and NGI have collaborated on the installation of offshore anchoring and foundation elements using suction/vacuum since the 1990s. We have together operated a range of pumping and monitoring equipment dedicated for suction anchor installation.”
Safe and reliable
“Framo’s main expertise is pumping systems for the marine industry, including equipment support from our large workshop facilities based in Norway and globally,” says Theodorsen. “Combined with NGI’s expertise within suction anchor technology and monitoring services, the know-how and basis for reliable, safe and efficient installation service is provided. The services include supervision, engineering and supply of equipment with operators during marine operations related to installation of suction anchor structures.”
Suction anchoring has become an attractive solution for the industry, as he notes, “The focus in the offshore wind market is to get the overall cost down, without reducing the focus on HES – health, environment and safety. Cost of installation plays a vital role, and with our proven technology, we enable the vessel to have a fast and reliable pumping operation without delaying the vessel from its other tasks.”
When asked how the offshore wind industry responded to the services provided by NGI and Framo, Theodorsen replies, “It was a milestone for Framo and NGI anchoring 20 wind turbines in one project. Never before has our technology pumped so many wind turbines in the same wind farm. An increasing number of companies invest in offshore wind to meet the future demand for energy, as well as to offer a more environmentally friendly energy alternative. It is a growing market where we are proactively taking part in this development. The Borkum Riffgrund 2 project opens up a new market for us in major wind farm developments and is an alternative to traditional installation methods.”
“The evolvement within offshore wind comes within economy of scale, fields and the turbines are getting larger,” he explains when asked about how the technology has been adapted to the offshore wind market. “This requires fast and reliable installation methods in order to get the cost down for the marine operations. The suction bucket jacket technology for offshore wind farms has gone from concept to reality during the last 5 years. Besides lowering costs due to the increased installation speeds compared to traditionally piled jackets, the concept provides for easier decommissioning and practically noise-free installation.”
“The foundation is installed by pumping water out of the buckets, creating a suction/vacuum, which ‘pulls’ the buckets into the seabed. This is a very clean process compared to installing monopiles. Suction anchor technology has a more environmentally friendly footprint. When pumped into place, the installation process is so quiet that no ocean species are frightened away – and it is easy to reverse the operation,” says Theodorsen when describing advantages of using suction bucket anchors offshore.
Basic suction anchoring for jacket foundations is similar for both oil and wind turbine platforms. But, in terms of scale, the number of foundations in a typical wind farm this installation has its benefits. “The design for suction buckets depends in both industries on the soil conditions. We have installed suction anchors in various soil conditions and down to 1,500 metres of water depth, since our first installations in the early 90s,” Theodorsen says. “Efficient installation methods are important within offshore wind in reference to the often high number of windmills installed on each field. Reduced installation time makes it economically beneficial compared to other methods.”
Simultaneously installing multiple buckets on a foundation isn’t without its challenges. But the key to success for Framo and NGI experience, as Theodorsen emphasises, “Together with NGI, FRAMO has installed close to 200 suction anchors. FRAMO has the pump experts and NGI has the geotechnical experts. Our well-proven and robust pump technology adapted to the pump skid is not sensitive for pumping dispersed material. The cavitation pressure for the pump is low, which is important in shallow waters.”
“NGI provides control and monitoring equipment for operation surveillance, which is integrated on our pump skid. The integrated instrumentation monitors the following parameters: inside and outside penetration depth, soil heave and bottom clearance, pumped water flow and leakage, total and differential pressure in the bucket, tilt, volume and pressure of water injection, if used. The pumps and hydraulic functions are operated by PLC control,” Theodorsen continues.
“Data is presented in customised real-time software, and data can also be streamed on local network to multiple clients on board or onshore. This enables us to have total control of the operation during the suction process. Our team coordinates this operation from the operator screen together with the NGI team offshore.”
Moreover, Framo’s expertise in previous offshore endeavours also plays a part. “We use known and proven pump technology developed over decades from other applications. Our technology has direct crossover from other segments in the offshore market – such as a one-man operated pump-skid and our LARS (launch and recovery system). Our LARS is the same system we use within oil recovery for skimmer operation in oil spill handling. This handling system has been developed for harsh environment and safety,” he explains.
Theodorsen points out that Framo’s experience and technology provides a range of advantages: “Our offshore team is a mixture of service engineers and the engineers who have been strongly involved in the development of the pumping system. This means that minimum time is spent on diagnostic once in field if unforeseen situations occur. The average pumping time offshore is only 3 hours per suction bucket jacket. Besides lowering costs due to the increased installation speed compared to traditionally piled jackets, this concept provides for easier decommissioning and practically noise free installation.”
Theodorsen sees a bright future for suction anchoring for offshore wind farms, saying, “Being able to offer a safe and efficient installation process with no need for subsea support – as well as having the benefits of using less steel in total, shorter installation time in one go, simpler removal and less noise during installation. We see the suction anchor installation as a good alternative to the more traditional installation method for offshore wind foundations.”
“As for the future, the size of turbines will increase – and when the size of turbines increases, the size of foundations must increase. Suction buckets jackets foundations provide better support and will be used even more in the future,” Theodorsen predicts.
Visit www.framo.com to find out more.