Problem:

Substantial winds are good for electricity production, but the very high wind speeds in storms can overwhelm traditional turbines. When the anemometer registers wind speeds higher than 55 mph (cut-out speed varies by turbine), it triggers the wind turbine to automatically shut off.

Solution:

Atsushi Shimizu, founder and chief executive of Challenergy in Tokyo has developed a vertical axis wind turbine (VAWT), with cylinders in place of blades, and which make use of a physics phenomenon known as the Magnus effect

While the motors require an energy input to spin, this is only up to approximately 10% of the power generated by the turbine. The advantages of this turbine, in its vertical axis and Magnus-effect-exploiting design, is that it can adjust to any wind direction, and power generation can be controlled in accordance with the wind speed. The latter is done via flaps or “cylinder wings” incorporated alongside the spinning cylinders, which can be adjusted to control the magnitude of the Magnus effect.

Shimizu’s calculations show that a sufficiently large array of his turbines positioned in typhoon ally could capture enough energy from a single typhoon to power Japan for 50 years

Because the Magnus effect acts as the main driver, the rotation of the turbine is almost 10 times slower than conventional blade turbines. This means they are less noisy, and Shimizu is also studying whether the lower rotational speed has a less detrimental effect on passing birds.

The 10KW version, installed in Ishigaki, Okinawa, has already recorded its first electricity generation during Typhoon Hagibis in October 2019 and the power and communication lines were maintained by continuously supplying the satellite antenna with power. Challenergy claim that their design can survive winds of up to 70m/s (156mph) but has an upper operating limit of 40m/s (89mph).

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