txt29
Senior Member.
A client of mine asked me for a consultation about an investment into wind energy, where a seemingly very attractive technology was presented to him. It is a 5kW, small, compact, safe and efficient wind turbine by a Czech company Simeti Wind Energy. They claim many advantages: low weight of the equipment, return of investment in 4 years, long service life min. 20 years, minimum requirements for operation and maintenance, no noise and non-vibratory technology, etc. (specification page / PDF).
Immediately after seeing the presentation leaflet, comparing their small turbine with 3 vertical blades of 2.4m² of inefficient design, to the classical wind turbine with the diameter of 8m and giving the output of 5kW at the wind of 12m/s, I've advised the client to keep away. However, his supplier of PV panels (honest business) insisted that the company is well referenced, founded by well-known and smart scientists, working on military projects, and having numerous installations, among others in Scotland, Antarctide, etc. I did not want to argue without hard numbers, hence I went home and tried to put them together.
First of all the design of the turbine, some photos and a presentation video:

The power of wind can be calculated by the following formula (https://en.wikipedia.org/wiki/Wind_power#Wind_energy)
P = ½ ρ A v³
Ρ = density of air. At sea level and at 15 °C air has a density of approximately 1.225 kg/m3 (https://en.wikipedia.org/wiki/Density_of_air)
A = swept area 5m² (the swept area of the Simeti turbine is in the best case very close to the double of the blade size of 2.4m² - see image simeti02.jpg and simeti06.jpg)
V = wind velocity 12m/s (see image simeti01.jpg)
P = ½*1.225*5*12³ = 5292 W
The maximum power a wind turbine can extract from the wind is given by Betz's law (https://en.wikipedia.org/wiki/Betz's_law) - it is 59.3%.
5292 W * 0.593 = 3138 W
So ~3kW is the theoretical maximum any wind turbine of these dimensions could reach at this wind velocity. Simeti claims the power output 160% of this theoretical maximum. Practically, the power can be only a fraction of this theoretical maximum, though. Even the best and the most efficient wind turbines achieve up to 80% of the Betz limit at peak in ideal conditions.
The turbine of Simeti is a vertical axis wind turbine. By design it is a Savonious wind turbine with flat blades (https://en.wikipedia.org/wiki/Savonius_wind_turbine). Their advantage is the simplicity and reliability, not the efficiency. The range of the power coefficient values for the conventional Savonius rotors is between 10% and 25%. (Review of savonius wind turbine design and performance by M.Zemamou, M.Aggour, A.Toumi).
In numbers, it means the Simeti turbine, instead of the claimed 5kW, could give maximally the power of some 300 - 800 W (at the efficiency of 10% to 25%).
However, even after the calculation, I would not accuse the company of a deliberate fraud. It could be still a mistake in the documentation, or perhaps just the result of a sloppy work. Therefore I contacted the company with my calculations, and asked them to explain the discrepancy. I received an answer that did not leave any doubts anymore. Mr. Milata, one of the founders of the company, wrote me that the high power output is possible thanks to their proprietary generator design, and due to the use of LENR cells. Mr. Milata did not answer anymore my reply where I asked why they need a wind turbine at all, when they have a generator capable of increasing the efficiency far above 100%. Of course, they also did not answer whether the LENR cells they use, stand for Low Energy Nuclear Reaction - that is the recent term used for Cold Fusion (https://en.wikipedia.org/wiki/Cold_fusion). I do not want to start the discussion about Cold Fusion here, because there are already several other threads about it at Metabunk.org, but even if such effect existed, it would be absurd if someone who is in the possession of such a Saint Grail, used it (together with a generator with the efficiency above 100%) just as an accessory of a primitive wind turbine.
I am sending the link to this thread to the Simeti Company too, so that they can advocate their stand, or correct me if I misinterpreted some facts, or gave wrong information.
Also, after digging the web, there is a much more detailed Russian web site of Simeti at http://ett-simeti.ru/
Immediately after seeing the presentation leaflet, comparing their small turbine with 3 vertical blades of 2.4m² of inefficient design, to the classical wind turbine with the diameter of 8m and giving the output of 5kW at the wind of 12m/s, I've advised the client to keep away. However, his supplier of PV panels (honest business) insisted that the company is well referenced, founded by well-known and smart scientists, working on military projects, and having numerous installations, among others in Scotland, Antarctide, etc. I did not want to argue without hard numbers, hence I went home and tried to put them together.
First of all the design of the turbine, some photos and a presentation video:




The power of wind can be calculated by the following formula (https://en.wikipedia.org/wiki/Wind_power#Wind_energy)
P = ½ ρ A v³
Ρ = density of air. At sea level and at 15 °C air has a density of approximately 1.225 kg/m3 (https://en.wikipedia.org/wiki/Density_of_air)
A = swept area 5m² (the swept area of the Simeti turbine is in the best case very close to the double of the blade size of 2.4m² - see image simeti02.jpg and simeti06.jpg)
V = wind velocity 12m/s (see image simeti01.jpg)
P = ½*1.225*5*12³ = 5292 W
The maximum power a wind turbine can extract from the wind is given by Betz's law (https://en.wikipedia.org/wiki/Betz's_law) - it is 59.3%.
5292 W * 0.593 = 3138 W
So ~3kW is the theoretical maximum any wind turbine of these dimensions could reach at this wind velocity. Simeti claims the power output 160% of this theoretical maximum. Practically, the power can be only a fraction of this theoretical maximum, though. Even the best and the most efficient wind turbines achieve up to 80% of the Betz limit at peak in ideal conditions.
The turbine of Simeti is a vertical axis wind turbine. By design it is a Savonious wind turbine with flat blades (https://en.wikipedia.org/wiki/Savonius_wind_turbine). Their advantage is the simplicity and reliability, not the efficiency. The range of the power coefficient values for the conventional Savonius rotors is between 10% and 25%. (Review of savonius wind turbine design and performance by M.Zemamou, M.Aggour, A.Toumi).
In numbers, it means the Simeti turbine, instead of the claimed 5kW, could give maximally the power of some 300 - 800 W (at the efficiency of 10% to 25%).
However, even after the calculation, I would not accuse the company of a deliberate fraud. It could be still a mistake in the documentation, or perhaps just the result of a sloppy work. Therefore I contacted the company with my calculations, and asked them to explain the discrepancy. I received an answer that did not leave any doubts anymore. Mr. Milata, one of the founders of the company, wrote me that the high power output is possible thanks to their proprietary generator design, and due to the use of LENR cells. Mr. Milata did not answer anymore my reply where I asked why they need a wind turbine at all, when they have a generator capable of increasing the efficiency far above 100%. Of course, they also did not answer whether the LENR cells they use, stand for Low Energy Nuclear Reaction - that is the recent term used for Cold Fusion (https://en.wikipedia.org/wiki/Cold_fusion). I do not want to start the discussion about Cold Fusion here, because there are already several other threads about it at Metabunk.org, but even if such effect existed, it would be absurd if someone who is in the possession of such a Saint Grail, used it (together with a generator with the efficiency above 100%) just as an accessory of a primitive wind turbine.
I am sending the link to this thread to the Simeti Company too, so that they can advocate their stand, or correct me if I misinterpreted some facts, or gave wrong information.
Also, after digging the web, there is a much more detailed Russian web site of Simeti at http://ett-simeti.ru/
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