However, this presents a problem when planning offshore wind farms. In the U.S. for instance, offshore wind farms can generate maximum power if placed in areas where the sea is over 200 feet (60 m) deep. This raises the cost of construction for the turbines significantly, which then increases the cost of production of renewable power, making the transition to emission-less power more difficult.
The vertical axis wind turbine
The horizontal axis wind turbine is not the only way to generate energy from the wind. Instead of a three-blade design, one can also use two blades placed vertically with a generator under them. Called a Darrieus vertical-axis turbine, this design weighs far less than the horizontal axis design and has a low center of gravity, making it suitable for offshore applications on floating platforms.
The adoption of these turbines has lagged due to one major drawback, their inability to withstand extreme winds. Unlike horizontal axis turbines that can simply turn away from strong winds, the Darrieus design cannot escape extremely powerful winds. Brandon Ennis, the technical lead for offshore wind at Sandia National Laboratories, had a solution to this problem.
In his design, the vertically placed turbine blades would be without a central tower but held together with adjustable guy-wires that can be shortened or lengthened to control the strain on the turbine blades during turbulent weather. Since the central shaft is not required in this design, the overall weight and the turbine’s size are further reduced, making it ideal for offshore applications. Sandia filed a patent application for this design in 2020.