SOLAR ENERGY APPLICATION IN RURAL WATER SUPPLY AND WATER TREATMENT

Abstract

Utilization of solar energy for pumping in rural drinking water supply schemes is a feasible solution especially for remote villages and homes far from grid system. Photovoltaic '(PV) pumps have predominant advantages in villages where grid connection is not available, good solar conditions exist, and the transport facilities do not exist. In such cases high reliability, autonomy of the system, and ease of operation present good arguments for the exploitation of solar energy. In this dissertation work, Cost comparison of photovoltaic pump and diesel generator is made for a life time of 25 years. Ethiopia is a land locked country that imports fuel oil. The cost comparison is made for Ethiopia where solar radiation varies from 4.55 KWh/m2 in July to 6.25 KWh/m2 in February and March with an average of 5.2 KWh/m2. Climate data have been searched from internet NASA Atmospheric Science Data Centre http://eosweb.lare.nasa.gov. Data regarding cost analysis have been collected from Ethiopian market and supplier's data archives. Cost comparison was made between a PV pump (solar powered pump) and diesel generator powered pump to supply a daily water demand of 52 m3/day to a population of Burkamisra village from a borehole to a service reservoir having a capacity of 25 m3. The life cycle cost of solar powered pump and diesel powered pump for a 25 years is about 2,638,406 Ethiopian Birr (158,090 USD) and 350,9553 Ethiopian Birr (210253 USD). According to the result obtained for this case study, even though the initial investment cost of PV pump is higher than the diesel generator powered pump, it has an economical advantage over a diesel generator powered pumps because annual operation and maintenance ; and replacement costs is significantly lower for PV pumps. For this particular case study it was found that the life cycle cost of water pumping is sensitivity to both solar insolation and price escalation of fuel oil. The change in price of fuel oil by 4% from the current market price results in an increase of 20 % of the life cycle of the diesel generator powered pumps where as an escalation of fuel price by 10 % results in an increase of about 80% in life cycle cost of diesel generator operated pump. Likewise, if the pumping system is designed based on the available maximum solar insolation the life cost of Photovoltaic pump is reduced by 4.5 %. In addition to lifting water from water sources, solar energy can also used for inactivation of microbes. The inactivation of microbes depends on duration of exposure, solar radiation and climatic condition under which the sample is exposed to sunlight. The iii overall efficiency of the SODIS under this study reduces the concentration of Total Coli form from high risk concentration to low risk concentration. The inactivation of microbes can be done at house hold level with low cost using PET or PVC bottle varying in size from 1 litre to 2 litre. The result obtained from the laboratory test shows, the percentage of reduction in bacteria varies in a range of 79.2 to 100% after disinfecting or treating with sunlight for water sample collected from different sources. It is also noticed that reduction of percentage in bacterial load increases with the time of exposure, that is, more E.coli were destroyed or killed as the time of exposure increased. In addition to the reduction in the numbers of total coli form, the Total dissolved solid, Turbidity and electro conductivity of water is improved after solar disinfection. Thus exposure of water reduces the number of total E.coli shows that the efficiency and effectiveness of solar energy in the area is promising in treating water by solar radiation or sunlight energy and a further detail study is recommended in a large scale to use this resource.