Horizontal vs. Vertical Axis Wind Turbines

Horizontal-axis wind turbines – where blades spin like a propeller on a stick – dominate the small wind turbine market. Yet, vertical-axis wind turbines – where blades spin like a cylinder around a stick – have the operational advantages of producing less vibration and noise. These benefits are especially important to small wind customers as they are often located closer to their turbines. However, most vertical-axis wind turbines on the market suffer from the substantial stresses of naturally occurring centrifugal forces trying to pull the devices apart from the center.

How Small Wind Turbines Work

When one looks at any wind turbine, the 2-dimensional face it presents is called the “swept area” – essentially a sail put up in the sky to capture wind-power. The bigger that sail, the more wind-power that is captured. In low winds – which are most common – a large swept area (big sail) is desirable to capture enough wind-power to drive the generator at full speed and maximize the production of electricity.

The problem arises as the wind speed increases because the power in wind grows exponentially (i.e., velocity cubed). If the turbine is unable to reduce the size of the swept area (sail is too big) to avoid the destructive forces in high winds, a catastrophic failure can
occur.

The SHAPEshifter 2.0 presents a large swept area in low winds – allowing it to capture enough power to drive the generator at full production – assured that as the wind speed increases, the turbine will dynamically reduce its size to avoid the wind’s destructive forces but still capture just the right amount of power to continue driving the generator at full production.