While oil is considered as the most precious commodity in most of the world, many places value water far more than oil. Shortage and contamination of water is a serious problem there. Water required for drinking, industry, and irrigation is badly needed in such parts, especially in the developing countries of Asia and Africa. There is sufficient underground and surface water present in these areas to meet the population’s requirement. What is lacking is the efficient means of pumping this water out for people’s use. Solar power water pumps are one efficient means to achieve this goal in the future.
Ideal Solar Power Water Pumps
Ideally, the solar power water pump is a low-cost, high-efficiency device, which converts the sun’s heat directly into mechanical power for driving the pump. Such a pump is able to use an array of tubular collector elements for heating air. The pump combines an evacuated tubular solar collector array with a diaphragm type pump. It is equipped with an internal heat exchanger, which uses heat from the heated air to generate steam from water. The steam drives the diaphragm pump. The heat exchange medium might be something other than water, for example freon or ammonia.
Models Of Solar Power Water Pumps
A number of different models have come out for the solar power water pumps. Two useful models came from Stephen Salter and Joanne Posthumus in April 2003. Both models are built on the nature’s principle of drawing water used by the plants.
The First Model: The first model from Salter and Posthumus consists of a well shaft that extends down in the ground to a significant length (as does a tree trunk). The shaft might extend down to the groundwater or to some depth below the ground surface, or to lift the reservoir of pure water above the ground. This results in gravity feed, a cost effective method of pumping water.
The Second Model: The second model uses a flat absorbent fiber, which is placed behind a black plastic sheet. Fiberglass is used as wick in this model. Since the black plastic sheet absorbs the solar energy, the reflectivity of the wick is not important. Both the fiberglass wick and black plastic sheet are enclosed in clear plastic, which is stapled to the wooden frame. A trough collects the condensing water droplets. There is a collecting jar for fresh water in the ground at the lower left-hand corner of the frame.
Prospects of the Models
With models of solar power water pumps by Salter and Posthumus, it is expected to get pure water from marshy or even contaminated soils. These pumps will also prove effective in water-logged areas or where saline water exists underground.