An Integrated Power Supply System For Water Pumping And Lighting In A Rural Village, Utilizing Renewable Energy Sources
This report consists of the design and development of a renewable energy based integrated power system for a community living in the village, Kahambana in the district of Monaragala, Sri Lanka, recognized as rural area. Agriculture is still the source of income of more than half of the people in the area. The area is water stressed and pumping of water required for agricultural works is obtained from a nearby reservoir by means of gasoline fueled engine driven pumps. Further, no national grid electricity is available because the village situated away from the main grid. In order to address these difficulties, this study formulated a low cost water pumping system together with an electricity generation system running on renewable energy for the benefit of community living in the village.
The proposed system did not consider the conventional direct water pumping method by wind energy as some of energy deficiencies and lack of required capacity were identified. The proposed system consists of irrigation pump powered by electricity generated by a wind turbine. Main components of the system are electric water pump designed for irrigation with necessary controls, power generation wind turbine and controls, battery bank and water storage tank. Energy consuming components such as pumps, motors and variable frequency drives were selected in order to operate at the best possible efficiency. For household electrification, efficient lighting was assumed. Net irrigation, required to be pumped does not remain constant as water requirement varies with the crop, crop maturity and rain fall which varies over the year. On the other hand wind speed varies over the year. Therefore, the wind turbine was selected so that even at lowest available wind speed, it produces energy required for water pumping. Wind speed data published by the National Renewable Energy Laboratory (NREL) for the district of Hambantota (lying in the same region in the wind atlas as the selected village) was used for the design calculations. Excess energy generated in certain periods of the year could be used for household electrification with a proper storage system.
Finally, the cost of construction and installation of the system was estimated and hence a comparison of unit generation cost of proposed system with present rates has been prepared. It shows the water pumping system is economical than the present engine driven system. However, the electricity generation rate is much higher than the rate of grid electricity. But, because of the difficulty (or high cost) of extending the national grid to this area, this is much feasible method to provide electricity to the village.