Ice, Wind and Structures

Offshore wind energy is a necessary part of the green transition and is expected to expand considerably, also into areas with sea ice such as the Baltic, the Bohai Sea and the Great Lakes in USA where the water depth and other geophysical conditions favor bottom-fixed structures. Bottom-fixed structures are installed in open water sites and produce electricity, but sea ice poses an unsolved challenge. Technical solutions for increased offshore wind energy in areas with sea ice such as the Baltic Sea have an impact beyond the goals of the EU and has direct positive effect on at least three of the 13 sustainability goals (#7, #9, #13) of the United Nations in addition to having indirect positive impact on five other goals (#3, #8, #9, #11 and #12). However, sea ice and sea ice action on foundations represents one of the major uncertainties for the design of structures for offshore wind in the Baltic Sea. The existing standards with requirements and guidance on how to design robust wind turbine support structure considering sea ice loads such as IEC614000-3-1 and DNV-ST-0437 are predominantly based on experience with Arctic Offshore structures for the petroleum industry contained within ISO19906. There are two important differences between offshore wind turbines and petroleum structures, firstly that the latter are large, stiff and almost quasi-static structures whereas wind turbines are slender and dynamic. Secondly, in the Arctic one can assume very large driving forces with almost infinite amounts of heavy ice whereas the Baltic differs as it has lighter ice conditions with typical design ice thickness ranging from 0.3 - 1.2 m. The are uncertainties in relation to defining the proper correlated ice statistics as input into models, and there are uncertainties in the deterministic and probabilistic models themselves. IceWise will address both of the major uncertainties and carry out novel research that will form the backbone of better standards.

IceWise addresses sea ice actions on offshore wind turbines. Offshore wind is one of the vital renewable energies for the future and Europe wants to reach at least 60 GW installed in EU waters by 2030. This means more wind turbines in the Baltic sea where sea ice is on the the major uncertainties. IceWise combines the competence of NTNU in ice mechanics and ice actions on offshore structures with competence within satellite remote sensing of sea ice at UiT to carry out world-leading research needed for Norwegian industry to reduce uncertainty in ice action estimations and to pave the way for improved operational planning and standardization of design method for offshore wind turbines. WP1 Sea ice statistics, WP2 Ice state definition and WP3 Probabilistic modelling, address respectively the sea ice statistics and ridges statistics from satellite remote sensing data (WP1), defining an ice state based on multi-modal data product and calculate deterministic ice loads (WP2) and probabilistic modelling of ice ridge and level ice action (WP3). The international DTU-Space (Skourup) will co-supervise the PhD in WP1 (UiT) and we plan for with two full day scientific workshops per year (at NTNU and at Aalto) with the researchers and the PhDs. Scientific papers published in high level international journals, high qualified personnel (PhD and master students) available for employment in Norwegian industry and development of better standards and guidelines for estimating ice actions on bottom-fixed wind turbines are three major results from the project. A steering committee with member from all Norwegian partners will meet 4 times per year and ensure good progress. it will also be two full day physical workshop with all partners annually. The PhD students will meet and be challenged by the industry with their applied perspective. DNV will be invited as observer to IceWise and Høyland is reviewing the new DNV-RP-C205 about ice actions to ensure that IceWise is complementary.