Friday, March 4, 2016

Small scale wind power

(日本語の記事はこちらです。)

Wind power, as a type of renewable energy, can be sold via the feed-in-tariff system in Japan.

Compared to solar power, wind power has drawbacks such as noise and more frequent malfunctioning because the blades of wind turbines are rotated mechanically by wind to make electricity. Knowing these drawbacks, I didn't have very high opinion of wind power before.

However, last summer I happened to find land that was potentially a good site for a wind turbine. Seeing the possibility of building a small wind farm, I decided to learn more about it.

Wind turbine

If the electricity is just for your personal use, any wind turbine is fine, but if you want to sell electricity to the power company, in Japan you have to use one of the wind turbines certified by the authorized institution.
As of February 2016, there were 13 certified wind turbines, many of them products of non-Japanese makers.
As mentioned in the Footnote *1 in the above link, the average wind speed of 5 m/s is necessary to achieve the annual energy production described in the table in the link.

For example, if the average wind speed is 5m/s, the model GW133 by Gaia-Wind Ltd, listed in the table, can be expected to generate 27,502 kW of electricity annually.

One kilowatt hour of wind power can be sold to the power company for 55 yen. A simple calculation shows what income in Japanese yen this would yield:

27,502 * 55 = 1,512,610 Japanese yen

Of course from this sum we have to deduct costs such as taxes, security monitoring costs, insurance and annual maintenance (which, in case of wind power, is indispensable), so the general view is that there is not much profit left.

Wind conditions

Needless to say, wind power depends on how much wind blows. Without wind, wind turbine is just an ornament.
It's crucial to know how much wind blows at the potential site, so I decided to check the wind conditions there.

The minimum required wind speed of 5m/s is about the same as the wind that keeps tree leaves constantly moving.

In order to monitor the wind conditions, I had a monitoring pole set up at the site, as shown in this video:




At the top of the pole, a small propeller is attached, which monitors the wind conditions.

The propeller is a commercially available product called Wind Tracker/Wind Logger, made by Logic Energy. It can measure wind direction and speed.

It's a low-cost product with a proven worldwide record. For more information, you might want to check this blog of a friend who works in Logic Energy:

http://www.windlogger.co.uk/blogs/news

On this blog you can also find introduction of our solar sharing project.

The graph below shows the result of the first 12 days of wind monitoring with this device.



These data show that there are large variations in the wind speed, which is not very good for a wind turbine. More importantly, the average wind speed was only 3.79m/s, which is much lower than the necessary 5m/s. Too little wind is not a promising sign for the project.

However, wind conditions should be monitored for at least six months, so I decided to be patient and continue monitoring before jumping to early conclusions.

(This article is a translation of the original Japanese post by Nobuo.)

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