so it makes them advantageous and affordable, but their low delivery capacity and labor-intensive nature make them highly unfavorable It has also been shown that the farming lands, cultivated by the farmers, produce significantly more crops if the farmers have access to a good and reliable water pump. The water pump can be used for to supply all the farmers in the village with the necessary irrigation water. Technically Dependent vs. Technically Independent The problem with technology imported from the west is that it is highly developed and it is difficult for the developing countries to adapt those highly developed techniques. If they do import these techniques, they will still be dependent on the west for spare parts or mechanics. It is of great importance that the energy generators, be it wind turbines, solar cells or generators, are user friendly. They have to be maintained by the locals, so the technique should not be too complicated. And even more important, if parts are broken, the locals must be able to make spare parts themselves, or spare parts have to be within the region. If the techniques used to generate energy are user friendly, it will be possible to create a local or regional market for spare parts and/or mechanics. This way a whole village or region will benefit from the technological -and more importantly- economical development. The technologies and materials used to make energy generators should be simple and cheap. A local mechanic should be able, after some basic instructions, to make and maintain a small wind mill or hydro turbine. Since there is almost always an old car, or other scrap metal available, these materials can be used to make a small energy generator. The three easiest and least expensive options to make a small energy generator are: a small
Figure 2
windmill, a small generator, or a small hydro turbine. Although making these applications rquires some mechanical experience, it does not require a lot of it. Numerous examples of home made energy generators can be found, and these techniques can be easily taught. A good example of how easy it is to make a small vertical axe wind mill is shown in figure 1. The blower fan can be found in old air-conditioning systems or ventilators. The wind mill will not generate fast amounts of energy, but it shows just how easy, quick and cheap it can be to construct one. Another example is the Savonius wind mill shown in figure 2. This wind mill can be made by someone with a little mechanical experience as well. A small generator can be easily build from a lawnmower engine. This will give users a constant energy supply. The down part is that they need to take care that there is a steady stream of fuel for the engine, this could be biofuel produced locally. A small hydro turbine is easy to construct, but has the drawback that it is dependent on water to produce energy. And when the energy is needed most to drive the water pump for irrigation, the power production will be the lowest. Nevertheless, this could prove to be a good solution for a community located near to a steady stream. Depending on the size of the energy generators, and the availability of storage possibilities, a small wind mill that produces some 500 watts at a wind speed of 9 m/s, can deliver electricity to 5 households equipped with at least two fluorescent lamps (8W), and run a water pump of 8 W, which is capable of pumping a maximum of 550 l/h. Two lamps and one pump may seem little, but can make a great difference. Another advantage is that when people gain some experience in building a wind mill, for example, the designs can easily be scaled up by a factor 11/2 or 2. Most important is that these locally manufactured energy generators can also be maintained locally. Their builders will know how the generators work and could easily spot what is wrong or not working properly should there be a malfunction, and they will not be dependent on or have to wait, for mechanics from the west to repair the energy generators. It must be said that research only focused on the generation of energy, and not it’s storage. The most obvious solution will be to use car batteries. These are not designed for the type of charge and discharge patterns frequently encountered in micro grids. But car batteries can still be seen as a cheap storage method, although its disadvantages.
www.osiris.tudelft.nl - maart 2009 osiris magazine
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