It was originally thought to be a movie in which science changes fate, but in the part of science, the movie did not go too deep, and it talked more about the hardships of the people on African soil.
As a science student, I have a lot of doubts about this windmill to generate electricity for irrigation, because there are too many unreasonable and unscientific shortcomings.
First of all, the amount of water that such a small pump can pump is very small. How much land can be irrigated is a big question. What I don't understand is that the technical pump can achieve irrigation, which means that the groundwater resources are sufficient, so why not use other methods for pumping irrigation, such as hand pumping, this thing has been invented for hundreds of years, and it is impossible to do without it. In addition, pumping irrigation There are hundreds of methods, and even the most primitive manual irrigation can achieve more water than the pump in the movie.
In addition, the film does not explain too much about the principle of windmills. In general, wind power generation is that the wind directly drives the motor, generates electricity, and the electricity drives the water pump, and then realizes irrigation, which can maximize the application of wind energy.
But in this movie, the process of generating electricity is a bit complicated. The wind drives the bicycle pedal gears, and the gears drive the wheels through the chain. Here the energy is lost once. The wheel drives the generator through friction. It must be known that the energy transfer efficiency of friction driving is very low, and it is lost again here. The generator generates electricity and charges it into an abandoned car battery. According to the shape, it should be a lead-acid battery. The charging efficiency is very low, and the energy is lost again here. Finally, lead-acid batteries drive the water pump for irrigation. This process is very tortuous and very inefficient.
The whole process is not explained in the movie, and some key principles are deliberately hidden. The movie says that irrigation can be achieved 24 hours a day. Personally, it is impossible to achieve 24 hours irrigation because the power of the bicycle friction generator is too small. .
My personal understanding is that the voltage required by the water pump is high, and the current achieved by the windmill in the movie is very small, so the windmill must continue to generate electricity, charge the battery, and then release a larger current to drive the water pump after the battery is sufficient. , but the discharge time should be much less than the charging time.
Therefore, although this movie is based on a true story, it has a lot of packaging components, and the scientific principles in it are even more difficult to scrutinize.
However, in the film, the depiction of human nature is still very successful, especially the role of the father, which is very plump, not rigid and facial, fully reflecting the multi-faceted nature of human nature. As an agricultural name, it has its advanced aspects and its limitations. . In the farmland, the part where the windmill model was broken was very successful, and it was the highlight of the whole movie.
Finally, a digression. Every time I see this kind of folk science story, I will think of Jules Verne's "Mysterious Island" (published in 1874), the kind of pleasure of changing the surrounding world from scratch by relying on scientific knowledge , there is no other work that can surpass it, hey, what have human beings been doing for more than a hundred years, it is not enough to make up a decent scientific story.
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