ABSTRACT
Positive displacement pumps have many advantages for wind pumping systems: robustness, low operational speed and hence low wear and maintenance cost, low capital cost, easy reparation with simple tools, high efficiency—especially for piston and diaphragm pumps—and finally, the capacity to pump from deep wells. Pumping water with high speed turbines (vertical or horizontal) coupled to centrifugal or screw pumps is technically possible too. Such configuration allows a more flexible use of energy both for pumping and other scopes, but its pumping efficiency may be lower than direct-driven wind pumps. Positive displacement pumps, either rotating or reciprocating, are suitable for self-construction, and their efficiency in general is more constant throughout a wider range of operational speeds, so they result potentially more suitable for the operation in wind-driven systems. This chapter focuses mainly on this case because positive displacement pumps can potentially provide the most efficient solutions in different situations, either in developing or in industrialized countries.
