Wind power is a rapidly growing industry worldwide, both on- andoffshore. Most of the good locations onshore in continental Europeare in use today, which has prompted a move offshore in recentyears. Europe has by far the most offshore wind turbinesinstalled, mostly located in the North sea.The low hanging fruits are locations with relatively shallowwaters (up to 45-50 meters), a high and steady wind speed and isclose to grid connections onshore. Big parts of the North Sea aresuitable for this, but many places with good wind conditionsworldwide are too deep. The next step for the industry is to moveto these deeper waters, with the help of floating wind turbines.The first prototype floating turbines have been running for acouple of years, with even larger, albeit still pretty small, windfarms in the planning stage.This thesis looks on the possibility of building large floatingwind farms in the future, specifically in the eastern most part ofthe North Sea - Skagerrak. Several different factors andstakeholders have been mapped out and important factors such aswater depth, wind speed and seabed conditions considered to createfour different future scenarios. Each scenario has been evaluatedtechnically and Levelized Cost of Energy (LCOE) has beencalculated to be able to compare the different locations.Since the technology is very new and under development, theinitial costs are high. This gives the lower LCOE of 149 €/MWh.Many new developments are however expected in the years to come,which would lower the investment cost considerably, by up to 40%according to some sources. This would lower the LCOE to under 100€/MWh.It is however also found that these investments carry many otherpositive effects, such as developing a new carbon neutraltechnology in Scandinavia which could become a big exportworldwide. The social acceptance of bottom fixed foundationoffshore (close to shore) and onshore wind power is also falling,and this would also be a big plus for floating offshore wind as itcan be built so far offshore it can't be seen from land. BothSweden and Denmark have big power plants closing in the comingdecades, nuclear power in Sweden and coal fired power plants inDenmark. These need to be replaced either by import or by newcarbon neutral power production.

In this thesis the Counter Rotating vertical Axis Floating Tilting wind turbine (CRAFT) has been explored by creating a simulation model in the program Simulink. The CRAFT prototype is a new type of wind turbine under development by World Wide Wind and Uppsala University with the aim to produce a large scale floating vertical axis wind turbine (VAWT) with two cone shaped counter rotating turbines. The objective of this thesis is to study the required size of the secondary generator in the CRAFT. The generator is required in order to keep both of the turbines rotating with the same but opposite rotational speed, even when the turbines are experiencing different wind loads. Further areas that are investigated are if certain parameters have a specifically high impact on the need for the secondary generator.  The objective was reached by creating a model of the prototype and implementing control algorithms for both the secondary and main generator in order to control the rotational speed of the turbines. The behaviour of the CRAFT was then simulated with different wind loads and varying parameters such as the size of the main load, the size of the power output to the secondary generator and the wing length of the lower turbine. The simulations showed that it is possible to keep the rotational speed of the two turbines equal and opposite even during turbulent wind loads with the chosen control algorithm. The simulation also showed that if a small deviation in the turbine's rotational speed is allowed, a secondary generator of only 1 kW is needed instead of the currently used 5 kW generator. It was also shown that the elongating of the lower turbine wings had a small and positive effect on the energy output of the CRAFT.