Tuesday, July 31, 2012
Vertical-Axis Wind Turbines
Though VAWTs have been around since the earliest days of wind energy research at Sandia and elsewhere, VAWT architecture could transform offshore wind technology.
The economics of offshore windpower are different from land-based turbines, due to installation and operational challenges. VAWTs offer three big advantages that could reduce the cost of wind energy: 1) a lower turbine center of gravity; 2) reduced machine complexity; and 3) better scalability to very large sizes.
A lower center of gravity means improved stability afloat and lower gravitational fatigue loads.
Additionally, the drivetrain on a VAWT is at or near the surface, potentially making maintenance easier and less time-consuming. Fewer parts, lower fatigue loads and simpler maintenance all lead to reduced maintenance costs.
Large offshore VAWT blades in excess of 300 meters will cost more to produce than blades for onshore wind turbines. But as the machines and their foundations get bigger -- closer to the 10-20 megawatt (MW) scale -- turbines and rotors become a much smaller percentage of the overall system cost for offshore turbines, so other benefits of the VAWT architecture could more than offset the increased rotor cost.
However, challenges remain before VAWTs can be used for large-scale offshore power generation.
Curved VAWT blades are complex, making manufacture difficult. Producing very long VAWT blades demands innovative engineering solutions. (Science Daily, 7/30/2012)