GH Craft Website 小型風車FAQ

GHDWT-10kW　FAQ

What is the price of your wind turbine system?

The price of current model varies depending on the customer requirements in terms of additional equipment and supporting structure. Please contact us directly via e-mail for detail information.
At the moment we are developing cost down model, to be released in early 2008. Final cost is still uncertain, but our goal is to release the model comparable with the price of solar generating system of equal size.

Can you tell me more about safety of your wind turbine system. Is it safe?

Our system is designed to easily withstand the 60m/s typhoon-class winds with all components fulfilling WTGS class II requirements. Rotor of the turbine is protected by means of triple security system:
a) Excessive overspeed activates drum break system that immediately stops the rotor,
b) The blade will be feathered using pitch control toward minimum load conditions,
c) Wind load will be reduced by means of the active yaw control system that will turn
　the rotor against the wind.
Safety and quality of our products comes first. If you check the market of the 10kW wind turbines you want be able to find many of them with all those advanced features.

I would like to install my wind turbine in urban area. Is the noise level of your system acceptable in the urban district?

Our turbine noise level is below 50db at 8m distance. Biggest contribution to low acoustic signature comes from the special blade design and duct construction that eliminates noise from the blade tips. Therefore, it is very quiet system that makes it ideal for urban district installations. Please check noise data (PDF file)

Is the vibration of the wind turbine acceptable in case of the rooftop installation?

Every wind turbine is a source of vibrations that can negatively influence the supporting structure. However GH Craft found a way to solve the problem. Currently we are using tower mounted vibration absorbers to successfully reduce vibration to acceptable level and our newest version of the system will yield more sophisticated shock absorbent system with floating support mounted on the rotor nacelle. Please check vibration data (PDF file)

How about the power curve?

Current system power curve can be seen in the following paper (PDF file)
However the system that we are scheduling to release next year has higher efficiency compared to the current model.

What is the advantage of having the duct?

A duct (diffuser) offers some advantages comparing to the ordinary wind turbine. Here are some of them:
a) Increase of the wind speed through the rotor plane,
b) Increase of the mass flow through the rotor surface,
c) Higher back-pressure behind the diffuser.
d) Higher tolerance for sudden wind direction changes (higher energy capture),
e) Reduction of the noise due the lack of blade "tip-loss" effect
f) Protection surface around the rotor,
g) Lightning protection of the rotor and generator improved,
h) Bird impact reduction.
Some of the reasons above are yielding engineering advantages such as higher power efficiency and some offer more practical benefits in terms of installation and environmental awareness.

I would like to see some of your wind turbines. Are there any installed and operating outside of your facility?

Yes, we recently installed 4 turbine systems at Prologis Centrair, Chubu International airport, Aichi (May, 2007) and 1 system at Mitsubishi Jisho Mminatomirai in Yokohama City (June,2007)

What is the weight of your wind turbine system?

Wight of the turbine itself is 1ton and weight of the additional support depends on the user requirements and support type. For example, our Yokohama unit overall weight is about 2.3 tons with total height of 11m)

What is the system annual energy production?

Please find necessary data about AEP on the following graph (PDF file)

What is the annual CO2 reduction equivalent of your wind turbine system?

Please find necessary data aboutCO2 reduction on the following graph (PDF file)

What materials are used for blade and duct manufacture?

Blade is made from carbon-fiber reinforced plastics (CRFP,) and duct, and radial stay-arms are manufactured using glass-fiber reinforced plastics (GFRP). All components contain solid foam core. This combination of materials allows us to create a turbine yielding high efficiency, durable construction and low cost.

What is the wind turbine's lifetime?

The lifetime of the system is minimum 17 years.

Is the maintenance of the wind turbine system necessary?

Yes it is. Machinery parts need regular maintenance annually. Electric parts such as condensers need a regular change as well.

How much is the running cost of the wind turbine?

Wind turbines are generating electricity from the wind, and wind is cost-free fuel. The costs that should be accounted are purchasing and installation costs together with maintenance costs.

How long does it take to set up turbine to operating conditions?

It depends on the place and conditions. For example, if we plan to place it on the top of the building that is under the construction, it is possible to set one turbine in one day. Construction sites usually have already crane and lifting equipment together with affordable amount of free space so installation could be performed smoothly.

How do you transport wind turbine to designated location?

For current model locally distributed in Japan, transportation system consists from two 4t trucks. For a new model, expected to be released in 2008, it will be possible to fit turbine in 20ft container.

10m high billboards are surrounding the rooftop on which I intend to place a wind turbine. Do I need some kind of device to make the turbine work?

All the obstacles in front of the wind turbine will generate turbulence and shadow the wind flow disturbing power generation. The least you need to do in such limited space as a rooftop is to place the turbine above the signboards. Also other obstacles such as elevator machinery, electric equipment and heating system rooms can affect the generating system to a large extent.

How many set ups are ordinary?

There are no standard for number of set ups. However, in Japan, it is restricted to the 5 turbines (50kW) when you are about to connect to the low voltage grid. High voltage grid can withhold up to 200 (2MW) turbines.

Will I experience low-frequency noise side effects?

There will be no problems with our 10kW turbines in terms of low frequency noise. In fact, we are having field tests for more than a year, but we haven't heard any complaint from residents or neighbors. However, in case of setting a wind turbine at the rooftop, some low frequency noise might occur at floor or lower levels due to the vibrations. Our wind turbine system is equipped with anti-vibration suspension system, but noise issue should be considered more thoroughly before construction.

Will I experience any electromagnetic waves disturbance after installing wind turbine?

There will be no electromagnetic disturbances caused by the wind turbine whatsoever. However due to the rotor revolution, antenna might experience some reception signal noise if it is located too near the wind turbine.