Lithium crystal circuit
Lithium crystal circuits were part of the  generation system of Starfleet vessels in the 23rd century.

Over-expenditures of  could damage the vital lithium crystals at the hearts of these circuits, as happened to the  in 2266 when chasing a Class J cargo ship into an asteroid belt. Forced to extend her shields around the vessel to protect it from asteroid collisions, the Enterprise burned out three of four lithium crystals, forcing the crew to supplement with battery power. The fourth crystal subsequently failed, over stressed from handling all of the ship's power. ()

See also 
 Dilithium crystal circuit
Energy technology