Power Generation ＼ Wind Power Station

On November 27, 2018, we took a charter bus from the school. After visiting Taipower Exhibit Center in Northern Taiwan and the Nuclear Power Plant, we went to Shimen's wind power station, which is the first wind power station in main island of Taiwan. Although it was cloudy and windy, there were two staffs in Department of Renewable Energy, Chih-Hao Wang and Chih-Kang Hsu, came north from Taichung for us to guide on purpose. We visited the interior of the wind turbine and the engine room. We have a deeper understanding of wind power because of their introduction. That was a valuable experience definitely.

Theory
Wind power is manufactured by blades after they are rotated and speed up the machine to transmit power to the generator.

Hand drawing

Shimen power plant and some wind power plants were established in the first wind power development schedule, Shimen power plant is the earliest built. It is VESTAS- V47 wind turbine made from Denmark. Here is the basic information:

Number of blades: 3	Voltage: 690.0 V	Hub height: 45 m	Diameter: 47.0 m	Rotor speed, max:  28.5 U/min
Cut-in wind speed:  4.0 m/s	Cut-out wind speed: 25.0 m/s	Rated wind speed: 15.0 m/s	Wind speed tolerance:  70 m/s	Service life: 20 years

The wind turbine is constructed of three blades. It begins generating when it is 4m/s and also turns the directions depends on different directions and speed of the wind. The blade diameter is 4 meters. The total height of the wind tower is the tower height and the blade length, about 23 meters.
The wind turbine can turn like an electric fan and also come into the wind automatically. According to the statistics, three blades are the most efficient design to generate power. Besides the larger the areas are the more power they generate.

Q and A
The following reply is from Heng-Shan Lin, a senior professional engineer of the Renewable Energy Division of Taiwan Power Company.
Q1： Can wind from any directions drive wind turbines? How to determine the orientation of the fan when starting building it?
A1： The wind from any direction can make the wind turbine generate electricity because the wind turbine can turn automatically. Taiwan is affected by the northeast monsoon in winter and the southwest monsoon in summer. When the typhoon comes, the wind comes from 360 degree, so that the wind turbines can generate electricity very much. However, when the wind comes so fast, the wind turbines turn the blade into an unstressed angle to protect itself from generation. In fact, before building a wind turbine, we will set up an observation tower to understand the annual average wind speed and wind conditions.
Q2： Is it a malfunction when the wind turbine does not spin? Is the wind turbine checked and repaired regularly? How long can one wind turbine last?
A2： Different brands of wind turbines have their lowest starting wind speed, or when the wind speed exceeds the set value, some brands wind turbines stop, and some brand fans reduce the blade force and reduce the speed. Early turbines were used for about 20 years, but now it can be extended to 25 years. The longevity of a wind turbine depends on whether the supplier can continue to provide spare parts and follow-up maintenance by the dealer.
Q3：How much is a wind turbine? How much does it cost for annual maintenance?
A3：A horizontal wind turbine on land costs about 57,000 NTD / 1kWh (not counting the labor cost of construction). A vertical wind turbine costs about 200,000 NTD / 1kWh. Maintenance costs are difficult to calculate, depending on how maintenance work is done.
Q4：Where are the current wind turbines we use made from? Is there any wind turbines made in Taiwan? What the difference of the wind turbines between the local and the foreign?
A4：The main brands of horizontal wind turbines are Enercon, Siemens (Germany), Vestas (Denmark) and GE (USA) so far. There is also a large wind turbine manufacturing industry in China, but Taiwan currently restricts imports of continental wind turbines. Taiwan had tried to make a horizontal wind turbine, but it was stopped by some reasons. There are still designs and production of vertical wind turbines in Taiwan.
Q5：If the wind turbines under the management of Taipower are manufactured by different countries, is there any difficulty in maintenance? Which country is the best wind generator?
A5：(1) There are currently five brands of wind turbines used, namely 80 in Vestas (Denmark), 34 in Enercon (Germany), 26 in GE (USA), 15 in Zephyros (Netherlands) and 6 in Gamesa (Spain). However, maintenance is more difficult and the cost is higher. (2) The wind turbines currently used on the market have their own advantages. It is hard to say which type of turbine is better.

Q6：How much is the cost of one kilowatt hour power generating at wind turbine on land?
A6：Simple calculation:
The cost of land-based wind turbine purchases is 57,000 NT$/1 kWh. At present, the wind power capacity factor of Taiwan's main island is about 30%, and once wind power can sell 2.3834 NT$.
1kWｘ24ｘ365ｘ0.3 = 2,628 kWh (Average 1kWh wind power generation per year)
2628ｘ2.3834 = 6,263 NT$ (Average 1kWh wind turbine generating revenue for a year)
If you simply consider the annual revenue and purchase costs, a wind turbine can be repaid for about ten years. Therefore, how to develop fan operation and maintenance technology to reduce costs and reduce failure rate and improve power generation efficiency is an important key to the success or failure of the wind turbine industry.
Q7：How does Taipower decide how much to purchase these wind power?
A7：Bureau of Energy, MOEA, sets the purchase price of any power generation. Based on the purchase price of land-based wind turbines, the cost of offshore wind turbines is about three times as much as land-based wind turbines. Therefore, there will be 5.8 NT$/1 kWh for an offshore wind power. Later, there are manufacturers who are willing to pay 3 dollars or even 2 dollars during competitive bidding. They are manufacturers’ different strategies.
Q8：Compared with wind turbines on land, what are the pros and cons of offshore wind turbines?
A8：(1) The advantages of offshore wind power location, one is no damage that will occur in the land, such as such as flying sand, drone collision and turbulence, and other one is eliminating noise to residents; unit capacity can continue to increase as long as the design allows. At present, offshore wind turbines in the world have been developed to 12 MW (the single unit of Taipower's land-based wind turbine has just set up in Penghu with a maximum capacity of 3MW. It has not yet been officially operated). (2) The disadvantage of offshore wind turbines is that the installation cost is high, and it is not easy to maintain and operate well. The bottom of the Taiwan Strait and the sea conditions are difficult to follow up which means there are many risks that are hard to assess and indirectly lead to more difficulties in lending.

The schematic diagram of offshore wind turbines near Changhua (provided by Taipower)

Q9：What is the impact of setting up a wind turbine on the environment and ecology? Will the environmental assessment be done before setting up a wind turbine? How to reduce the negative impact?
A9：(1) Strictly speaking, the low frequency noise of wind power bothers surrounding residents. Other influences like the blades hit migratory birds, piling effects white dolphins, and even some scholars say that it will affect the reproduction of the clams, which have been discussed academically. (2) An environmental impact assessment must be made when setting up a wind turbine. How to reduce the negative impact: If they only discuss the effects of low frequency noise, they must set an effective method in the low-frequency noise regulations (the current noise regulations are flawed).
Q10：How to reduce the noise generated when the wind turbine is turning? Will residents protect? How to communicate with them?
A10：The turbine rotates to produce noise, which comes from the motor operation and the blade rotation. Taipower has also been studying how to reduce noise, but it is only theoretical. (2) Affected by noise, of course, households close to the wind turbine will be affected, and when the strong northeast monsoon comes, the downwind (the household under the southern wind turbine) will be affected. (3) Taipower continues to communicate with residents. However, when it comes to money compensation, it is necessary to issue large amounts of funds in the whole village or the whole township. It is no any basis of law, and it also causes the most difficult part for Taiwan to develop wind power.

Situation and Conclusion
◎Pros:
1. Renewable energy (the most important establishment in green power).
2. Short construction.
3. No air pollution, radiation, and carbon discharge.

◎Cons:
1. Variance in construction cost.
2. Market saturation onshore, challenges offshore.
3. Noise pollution. Highly depends on weather.

This is our first time to visit the towel of the wind turbine in Shimen wind power plant. The staff explains that they have to climb up about forty-five meters high to maintain. We also understand the reason why the wind turbine can turn like a fan because of the wind speed. With too strong or small wind, it cannot make a wind turbine move.

Walking into the wind turbine	The ladder in the tower
Explaining by the maintenance technician	The safety equipment in the tower

After Heng-Shan Lin answered the question about the challenges to the development of wind power station, we suddenly realized that there will be more problems we have to face in the future. For instance, it is hard to set the wind turbine offshore since the debt and the influence with inhabitants and environment.

Instant display of power generation	Interview of the maintenance technician
The machine room near the wind turbine	We looked around the machine room