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October 2012 www.sname.org/sname/mt A New Footing Analyzing the viability of ?oating oshore wind turbines (mt notes) The viability of wind energy is gaining ground. According to The World Offshore Wind Market Forecast 2012- 2016,? recently released by international energy business advisors Douglas-Westwood, more than $63 billion is expected to be spent on new oshore wind installations over the next 5 years. e world will see new installed capac- ity amounting to 15 GW during that period, averaging 3 GW per year, up from 600 MW per year in the ve years to 2011. From onshore to oshore As of this writing, all oshore wind farms have been based on bottom-xed foundations in water depths of around 30 m. As installations move to greater depths, oating oshore wind turbine (FOWT) foundations can become cost-eective alternatives. Going from onshore to bottom-fixed turbines was a challenge both in terms of marinizing the onshore-based technologies and in determining the interaction between the loads generated by the turbine and the loads generated by the marine envi- ronment, such as waves and currents. e move from a bottom-xed to a oating oshore turbine foundation introduces another level of complexity with the added requirement of considering the mooring system and the oater response to the operating environment. As the oil and gas industry began the move into deeper water and new concepts like the spar were devel- oped, there arose a need for more complex computer programs that could capture more accurately the loads acting on oating structures. e general approach for the available analysis programs for FOWTs generally has been to combine a mooring/oater program used BY LARS SAMUELSSON AND QING YU The three FOWT conceptual designs selected for the case studies were adapted from existing designs in the public domain: from left to right, the OC3- Hywind Spar, the MIT/NREL monocolumn TLP, and generic WindFloat semisu bmersible concepts.