Peikko’s cage rock foundation is used in Flatnahagi wind park project in the Faroe Islands. The remarkable savings that Peikko’s solution offered in terms of concrete, reinforcement and excavation support Faroe Islands to meet their ambitious sustainability targets.
Did you know that the Faroe Islands is one of the world’s leading nations in producing sustainable electricity with over 50% of the nation’s electricity deriving from renewable energy sources? There is great potential in the islands for the exploitation of renewable energy: hydropower, wind and tidal power. The main energy supplier of the Faroe Islands, SEV, has officially announced that the goal is to have 100% green energy production by 2030. In 2018, 18.1% of the main electricity was from wind, and the numbers are only increasing.
Due to the favorable weather conditions and the need to meet the strict energy targets, there are several wind parks being built around the islands. Flatnahagi is one of the most recent of them, with 6 turbines built with Peikko’s cage rock foundation solutions. The turbines’ rated power is 2.0/2.3 MW and their hub height 78 meters. The E-82 E4/S/77/5K/01 turbines are manufactured by Enercon. The wind park is built and operated by P/F Flatnahagi, a company owned by P/F Magn and Lív, a pension and insurance company in the Faroes. The foundations are constructed by WKA GmbH, and the park is estimated to be operational by 2023.
Sustainable and durable solution
The Faroe Islands is a challenging place to build to. First, the climate conditions in the area are particularly harsh due to heavy winds and rain, which also delayed the wind park construction phase. Secondly, the soil composition is peculiar; the islands are rock based, but the bedrock is mainly basalt, not granite as in the mainland Europe. Basalt is known to be a fragile rock type, which sets special requirements for the wind turbine foundations and their installation. Due to its composition, basalt is not well suited for producing high-strength concrete, which is therefore mostly imported from Norway.
Peikko’s Cage Rock Foundation excels in locations with weak bedrock. The loads are transferred from the tower to the rock through the anchor cage, concrete and 12- to 16-meter-long rock anchors. The use of concrete and a wider base keeps the quantity of rock anchors low – each tower is supported with 16 to 30 rock anchors. The design consists of rebar, PSB® reinforcement and FATBAR® post-tensioned rock anchors. With an installation team of only 8 men, the foundation assembly time is 6-7 working days.
“Flatnahagi project is Peikko’s first wind turbine foundations delivery to the Faroe Islands. However, Peikko was already known in the islands for our DELTABEAM® solution in previous construction projects”, said Henrik Harder, Peikko’s Sales Manager.
Peikko’s solution came into play when the technical consultant of the Flatnahagi project, SPENN, was searching for alternative solutions that could reduce the volume of concrete. Thanks to the preliminary geotechnical investigations the rock quality was known and acknowledged as being of a good quality.
“I wrote “rock anchors” in Google search engine, and the first result was Peikko”, commented Árant Jacobsen, Project Manager of SPENN. That was the starting point of the project.
After contacting Peikko and some initial calculations made, it was very clear that Peikko’s foundation solutions would be far more economical and sustainable than the competing solutions. For instance, a cage rock foundation uses only 15% of concrete and 17% of reinforcement of the amounts needed for a traditional solution. The expected excavation is more than 800m3 less and the foundation diameter over 10 meters less. These are numbers that cannot be ignored and that bring in significant savings and a sustainable approach.
Teamwork and collaboration
The project continued with an initial ramp-up meeting, detailed design and planning by Peikko’s engineering team, and tight mutual communication. As the soil type sets specific requirements for the foundations, Peikko doublechecked the suitability of the solution against these requirements. The close communication and clarifying all the questions as soon as they arose have been the keys for leading a successful project. Peikko’s deliveries for Flatnahagi were executed from factories in three countries and combined as three delivery batches on weekly ferries from the mainland. Good communication and project management tools enabled smooth deliveries with no delays.
“Peikko's many years of experience and innovative ideas in the field of foundation design were once again the guarantee for a successful project. Thank you for the entire Peikko team for the support and the pleasant cooperation”, commended Dirk Eger, Managing Director at WKA GmbH.
Peikko has been much more than a design and component supplier.
“Peikko is supporting customers before, during, and after construction. Our clients often ask for our advice on the suitability of the materials, and our design team is happy to support them. Peikko always prefers to clarify all the issues before any unnecessary problems occur”, explained Undīne Vītola, Peikko’s Sales Engineer for Wind Energy Applications.