In the current world, fossil fuels and non-renewable energy sources are being phased out and renewable energies are taking their place. Electrical energy from these renewable energies are more difficult to store than fossil fuels. Transportation and feedstock for industries can also not always be supplied through electricity. Here, hydrogen has the potential to be a good alternative, clean energy source. However, hydrogen is currently either not produced in a renewable manner (grey hydrogen), or renewable but too expensive (green hydrogen). Grey hydrogen is less expensive at a cost of around 1.50 €/kg, while green hydrogen has a cost of 2.50 - 5.00 €/kg. A new method to produce green hydrogen at a lower cost is the hydrogen turbine developed by HYGRO. This method uses an integrated electrolyser system in an existing wind turbine to produce green hydrogen and has the potential to drop the cost of green hydrogen to a more competitive level. Since this new method changes design questions of the wind turbine, a potential increase in specific power, along with a decrease in cost of hydrogen (expressed in levelised cost of hydrogen, or LCoH) is expected. In order to research these effects, this thesis investigated the effects of an increased specific power on the cost of the components of the turbine and its design, as well as the amount of hydrogen it was able to produce. This investigation was done through a model along with a case study to determine the results for a specific case. The increase in specific power was achieved by increasing the power rating of the turbine, but maintaining a constant rotor radius and maximal rotor speed. The case study performed investigates the effects based on a 15 MW reference turbine, which has a specific power of 331 W/m2. Its power rating was increased from 15 MW up to 35 MW and the resulting costs and production amount were compared to determine an optimal point were the resulting LCoH would be lowest. The result of the case study suggests that if the 15 MW reference turbine was converted to a hydrogen turbine, the optimal power rating would be in the range of 25-30 MW, where an LCoH of around 1.69 €/kg was achieved. These power ratings are equal to a specific power range of 553 - 663 W/m2 or 66 - 100 % higher than the reference. Through an error analysis, the results were validated and determined to have a reasonable degree of certainty. The main component of the model that could be improved upon to increase its robustness is the wake loss model, which was not precisely modelled but does have a significant effect on the results.
The increase in specific power suggests that hydrogen turbines have the potential to perform at higher power ratings than the wind turbine it is based on. This would allow the green hydrogen cost to drop significantly, down to a value were it is nearly competitive with grey hydrogen.