the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 10 Feb 2025
Effect of Rotor Design on Energy Performance and Cost of Stationary Unmoored Floating Offshore Wind Turbines
Abstract. This paper investigates the effect of rotor design on energy performance and cost of a Stationary Unmoored Floating Offshore Wind turbine (SUFOWT). A SUFOWT is a Floating Offshore Wind Turbine (FOWT) for which a dynamic positioning (DP) system is used in lieu of a mooring system for station-keeping. It is particularly well suited for deployment in the far-offshore.
Previous studies have shown that positive net power production can be achieved with SUFOWTs depending on number and size of thrusters, and wind turbine characteristics. However, they did not consider rotor design. This gap is addressed in the present paper. The study is based on a physical engineering model. The wind turbine rotor design is represented by its rated induction factor.
Results show that the optimal rated induction factor is smaller than the usual value of 1/3 both from the perspective of energy performance and cost of energy. Thus, wind turbine rotors designed for SUFOWTs should be developed to optimize their cost. However, results show that the cost of energy reduction is somehow limited, of the order of 2.5 to 4.3 % for the considered designs.
- Preprint
(809 KB) - Metadata XML
- BibTeX
- EndNote
Status: open (until 13 Mar 2025)
-
RC1: 'Comment on wes-2025-15', Anonymous Referee #1, 15 Feb 2025
reply
The paper deals with stationery unmoored floating wind turbines. This topic is very relevant to wind turbines deployed in very deep waters far offshore where mooring costs would be high. The paper initially presents a very good overview of relevant literature. It then applies simple actuator disc theory for wind turbines to evaluate the impact of rotor design on the energy yield and cost of such turbines. The quality of the writing is overall very good and grammatically mistakes are very limited. The presentation of graphs and tables is also very clear. However the following major comments are being brought forward:
1. Section 2: The study ignores the hydrodynamic loads of the waves when sizing the thrusters. This assumption is unrealistic, considering that at high wind speeds the wave induced loads on the floating platform are often larger in magnitude than the wind turbine thrust.
2. Section 2.1: The formula for the thrust coefficient CT derived from the momentum theory is only applicable for low inflow factors. For induction factors above ≈0.38, the momentum theory is invalid and CT increases linearly with the induction factor. This fundamental limitation of the simply actuator disc theory is not factored in the study.
3. Section 3.1: The derivation of Eqt. (7) is not explained in enough detail. It is unclear how this equation for the turbine power is derived by equating the wind turbine thrust to the thrust of the dynamic positioning thrusters.
4. The impact of rotor design is solely based on the disc average axial induction factor. How this will impact the rotor solidity, mass and cost is not assessed in enough detail. Thus the cost model is not convincing.
Citation: https://doi.org/10.5194/wes-2025-15-RC1
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 51 | 15 | 3 | 69 | 1 | 1 |
- HTML: 51
- PDF: 15
- XML: 3
- Total: 69
- BibTeX: 1
- EndNote: 1
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1