Stochastic study of windpumps with reservoir in Southern High Plains

Hourly wind-speed data for 11 years (1983-1993), historical groundwater tab le data, and performance test results under varying conditions for two mech anical windpumps and one electrical windpump were used at Bushland, Tex., t o evolve major recommendations pertaining to: wind-powered irrigation manag ement. Stochastic analysis of hourly wind-speed data showed that the averag e daily wind speed lies most frequently in the range of 5.5-6 m/s, with the upper and lower limits being 16 and 4.5 m/s, respectively. This is conduci ve to most of the wind energy conversion systems manufactured today. The di scharge of the electrical windpump was more than four times higher than the mechanical windpumps at high wind speeds. The performance of the electrica l windpump was also much better at a high operating head (60 m) than at low operating heads under high wind regimes, showing its suitability for groun d-water pumping in the Southern High Plains. Stochastic estimation of daily windpump discharge revealed that pumping rates are high in the spring and autumn seasons, favoring irrigation of a winter wheat crop. The trend of va riation in unit reservoir capacity, under different levels of daily demand and risk, shows that wind-powered irrigation systems with high risk can be adopted under higher economic return conditions. Though the results obtaine d in this study are applicable mainly to the Southern High Plains of the Un ited States, the methodology developed will have general applicability.