Researchers have begun to show that a floating axis wind turbine (FAWT) could in fact generate cheaper energy than the more standard offshore horizontal axis wind turbine (HAWT).
As shown in the image above, there are several types of floating wind turbines available, but researchers from the Korea Advanced Institute of Science and Technology and University of Tokyo have showed that the installed cost per rated power of the floating axis wind turbine (FAWT) is 50% and 57% of those in the referenced HAWT (horizontal axis wind turbine) and guyed VAWT (vertical axis wind turbine) configurations, respectively.
On top of that, the estimated cost of the electricity produced in a FAWT-style farm would be approximately 25% lower than that of the base HAWT.
The researchers published their results in the journal Environmental Letters and outlined the major merits of FAWT:
|(1)||The float supports the weight of the turbine and most of its axial load. The bearing rollers swivel like swivel casters of a desk chair. It allows relative heave motion of the rotating float to the bearing mechanism so that only the thrust force of the turbine is on the bearing mechanism. The thrust force of a wind turbine is less than 1/10 of the weight of the VAWT mechanism.|
|(2)||Power output from the turbine is obtained from torque of the rotating float by rollers contacting on the cylindrical surface of the float. Since the drive train is not in a limited space like the nacelle of a HAWT or the shaft of a VAWT, restrictions on the weight and size of the mechanism are lighter than those in other turbine concepts.|
|(3)||Non-firm support of the turbine axis avoids concentration of the load. Since the weight and bending moment of the turbine are not directly on the drive train, the configuration leads to lighter structural requirements. Gyroscopic moment of the turbine and the float stabilizes the direction of the turbine axis in wind fluctuation.|
|(4)||FAWTs inherit the simple mechanism and low maintenance cost of VAWTs.|
|(5)||Installation of FAWTs does not require floating cranes and other specifically designed service vessels.|
“We have to reassess the costs of renewable energy and explore new possibilities of energy generation which can be substituted for a part of the present share of nuclear power,” the authors write. “In Japan, wind power is one of the prospective candidates. However, in Japan, flat land and shallow water area available for the construction of new wind farms is very limited. Therefore, there is an urgent need for low-cost offshore wind turbines that are applicable to deep water regions.”
The authors are well aware that their hopes may run into difficulties and unknown challenges, but they are confident that the FAWT will help them find a way to create low-cost offshore wind power.
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