About the Windmills

Windmill on the roof of a house in our estate, in Kędzierówka.

The Dutch from the Institute of Technology in Delft have developed an excellent windmill on a vertical axis (VAWT, Darious type), which "likes" wind swirls. This unique feature and several others (starts on its own, without the previously used assistive devices, does not produce vibrations and sounds, as working on the basis of the lifting force, and not on the resistance, has a very high efficiency, much higher than the windmills of the Savonius type), qualifies it for use in urban areas. The authors have developed also guidelines for its setting on the roofs. However, they have tested only flat roofs. Houses built by us, due to the dedication to our tradition, always have a slope of 45 degrees (100%). We therefore examined what is happening with the wind on the ridges of such roofs. The result was excellent. Several months of measurements have shown that, above the ridge, a nozzle forms, wherein the wind has a higher speed (on average 108%) than in an open space at the same height.

Power output of the windmill is proportional to the second power of the average wind speed, thus, it can potentially be not lower, but 17% higher than in an open field!

In the construction of windmills producing electricity, one of the most difficult issues is to synchronise the generator with the rotor. The problem stems from the fact that we are dealing here with very different phenomena, having different characteristics: magnetism and the flow of fluid, which is the air. The efficiency of the windmill and the generator otherwise dependent on the wind speed and the level of the received energy.

The purpose of our windmill is the production of heat, and on this path, the electricity mediation is unnecessary. Joule's heat apparatus allows for the conversion of mechanical energy obtained from the windmill to the heat with an efficiency of 100%. Such a device was applied in 1845 by James Joule to determine the heat equivalent of mechanical work.

As a result of the replacement of the generator by the Joule's heat apparatus, a homogeneous system was obtained: both the windmill on the roof and the heat apparatus processing its energy are devices based on the fluid flow. This allows for their full synchronisation, with the use of full power of the windmill, regardless of wind speed. And that means a larger efficiency of the whole unit.

Wind powers the rotor, which rotation without any gears is transmitted by a rigid axle to the heat apparatus, where the energy is transformed into heat. The heat apparatus is filled with oil, which is also used to transfer energy into the central reservoir of heat in the house. As a pump to drive the flow of oil, we used "the Joule's heat apparatus" itself. While maintaining very high efficiency, the whole system has become extremely simple, and it usually determines the final evaluation of the project.


Our consultant is dr.Tomasz Szuster from Faculty of Power and Aeronautical Engineering, Warsaw University of Technology.

Work on this idea is not our priority, and this is because the amount of energy, which is carried by the wind in urban areas is much lower than the one obtainable from other sources, e.g. from the sun. But this idea has some interesting features. First, the distribution of wind energy in time is opposite to the one of solar radiation: winter is the most windy, and the summer is the least windy. The other interesting feature is the fact that the efficiency of Joule's heat apparatus does not depend on the operating temperature. If the windmill receives the amount of energy, which will raise the water temperature in the tank, say about 10 degrees C, then this increase in temperature will be the same when the tank has initial temperature of 30 degrees, and when it has 80 degrees. As a result, the system is potentially a perfect complement to low-temperature energy sources.