Patent ID: 8322447

Claim:
An apparatus usable with a well, comprising: an operator disposed in the well and configured to respond to a differential pressure between hydraulically isolated zones of the well to produce mechanical motion; a generator disposed in the well and configured to convert the mechanical motion into electricity; a piston; at least one valve coupled to the piston; and a housing translatable containing the piston, in which the piston defines a first chamber on one side of the piston and a second chamber on another side of the piston, wherein: the mechanical motion is produced by said at least one valve alternately controlling application of the differential pressure across the piston, resulting in movement of the piston; the hydraulically isolated zones comprise a first zone and a second zone; the at least one valve is adapted to alternate facilitation of communication between the first and second zones and the first and second chambers; and wherein the at least one valve comprises a first pair of valves coupled to the first chamber and respectively coupled to the first and second zones and a second pair of valves coupled to the second chamber and respectively coupled to the first and second zones.