Technical-economic evaluation of a hydroelectric micro-central driven by a solar-powered water storage system for agricultural applications

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.

The region of Arequipa, located in southern Peru, is benefited by a high solar energy resource during most part of the year: 1100 kWh/m2, approximately. Parts of this region are located in the Andes, parts which also happen to be the ones that are isolated from the national electrical grid. The geography of these zones is considerably diverse and presents height differences all over the territory. These two characteristics: solar radiation and irregular topography, allow the use of a hybrid technology to generate electrical energy harnessing ground level variations. These two necessary features were identified in the district of Majes, Arequipa. A hydroelectric micro-central driven by a solar-powered water storage system was installed in the facilities of a winery located in this district, to supply part of its electricity demand. The micro-central was composed by three systems: the solar pumping system, the reversible pumping-power generation system and the water storage system. Performance tests were developed to evaluate the efficiency of the micro-central operating in real conditions. Parameters like the water mass flow pumped, the water mass flow through the turbine, the electricity produced through solar energy and the electricity produced by the system were studied. The hydraulic, mechanic and electric power for the maximum water mass flows tested were 1500, 500 and 400 W, respectively. The whole system attained a global efficiency of 27%, approximately. An economic evaluation was also performed, comparing two alternatives for the generation of electricity: a solar photovoltaic system feeding the electric load directly and the solar-powered hydroelectric micro-central. The aspects influencing on the economic indicators involved the availability of electrical energy produced by the systems during the day and the points of maximum performance for the operation of the micro-central determined for each month of the year according to the incident solar radiation in Majes. The study showed the feasibility of using solar energy to store water in high reservoirs as potential energy for the generation of electricity in isolated zones where geography allows the application of this technology. With the operation of the micro-central in the winery, some operational costs can be reduced, while maintaining environmental responsibility with a sustainable approach.