FAQ | Japan Wind Development Co., Ltd.

Here, we answer your most common questions about wind power.

What is wind power?: Wind power is a method of generating electricity where the kinetic energy of the wind is used to turn a wind turbine (windmill) and converted into turning force. Once the gears (step-up gears) speed up, a generator is used to convert this motion into electric energy. Because the direction and speed of the wind are constantly changing, there is a function to use computer control to change the direction and output of the nacelle (the housing that contains the machinery on the upper part of the wind turbine).
About how many wind turbines are there in Japan?: Currently, as of the end of December 2019, there are 2,414 wind turbines in Japan, and they produce about 3,923 million kW of wind power (according to research by JWPA). Many of them are installed along the coast or on top of mountains, and they are especially concentrated in Hokkaido, Tohoku, Kyushu, and other areas known to have strong wind.
What is the difference between kW (kilowatts) and kWh (kilowatt-hours)?: One kilowatt-hour is the amount of power obtained from one full hour of operation by a one-kilowatt power facility. One 1500-kW wind turbine is expected to generate about 3 million kWh of power annually. This is equivalent to the amount of electricity used by 800 to 1,000 general households.
How do you operate and maintain wind turbines?: The operation and maintenance of Japan Wind Development Group’s wind turbines is handled by our subsidiary EOS Engineering & Service Co., Ltd., and is monitored remotely 24 hours a day. We also have eight service locations nationwide, so the nearest site can dispatch personnel if a wind power generator malfunctions.
About how frequent are maintenance inspections?: Our technicians can provide either daily patrol inspections or periodic maintenance inspections every six months.
At what wind speed do wind turbines begin to produce electricity?: They begin to turn at a speed of 2 meters per second, generating power in the range of 3 to 25 meters per second.
Are there any problems with the strength or safety of wind turbines?: Because wind turbines must be able to operate in harsh natural environments, they are designed and manufactured based on IEC and other international standards. And because Japan is uniquely prone to natural disasters such as earthquakes and typhoons, we conduct design based on relevant domestic laws and regulations, such as the Building Standards Act, and obtain the proper permissions before construction to ensure there are no problems with strength or safety.
What measures can you take against typhoons?: During typhoons or other strong winds, equipment is stopped (cut out) around a windspeed of 25 meters per second and control the turning force from the strong winds by putting the blades in a parallel position to the wind (feathering) so that they do not pick up the wind.
How do you calculate the conversion of the amount of power generated into the amount of carbon dioxide (CO₂) reduced?: The amount of carbon dioxide (CO₂) emissions reduced can be calculated by subtracting the coefficient of 0.000025 (t-CO₂/kWh) for the CO₂ emissions generated by the raw materials, building materials, fabrication, etc. according to documents published by the Central Research Institute of Electric Power Industry from 0.000488 (t-CO₂/kWh), the CO₂ emissions conversion coefficient from the official gazette "the CO₂ Emission Factor of electric utility companies, based on 2018 actual data, 1/7/2020" by Japan’s Ministry of Economy, Trade and Industry and Ministry of the Environment (Nov. 6, 2012).
Amount of carbon dioxide (CO₂) reduced = (Amount of power generated × 0.000488 (t-CO₂/kWh)) − (Amount of power generated × 0.000025 (t-CO₂/kWh))