Power-generating apparatus for downhole tubulars

An energy generator apparatus for a rotatable tubular having an outer surface defining an outer diameter of the rotatable tubular and extending downhole along a wellbore comprising:

• a tubular sleeve mounted over the rotatable tubular, the tubular sleeve comprising a first clamshell portion and a second clamshell portion and end collars overlying and retaining opposing ends of the tubular sleeve, the tubular sleeve having an inner surface defining an inner annular groove;
• a first energizing portion mounted on the outer surface of the rotatable tubular and received in the inner annular groove of the tubular sleeve, the first energizing portion being drivably rotatable by rotation of the rotatable tubular;
• and
• a second energizing portion attached to the tubular sleeve within the inner annular groove of the tubular sleeve, the second energizing portion being supported concentrically about the first energizing portion and rotatable relative thereto;
• and
• wherein, when the rotatable tubular rotates the first energizing portion rotates relative to the second energizing portion, electrical current is generated from one of the first or second energizing portions.