The Central Power Battery is located on the planet Oa and stands as the epitome of Maltusian science. The Central Power Battery is the reservoir of power for the emotional spectrum of willpower, and channels the energy used to empower the Green Lantern Corps. All of the green energy housed within a Green Lantern ring comes from a smaller battery, which in turn, functions as a conduit to the Central Power Battery on Oa.
The Central Power Battery has been destroyed and rebuilt several times. It was first destroyed several years ago by the forces of Krona. Unfortunately, the battery exploded during an assemblage of all 3,600 members of the Green Lantern Corps, several of whom were killed instantly. The surviving members struggled valiantly to put out the rampaging inferno of green energy that swept across the Oan Citidal.
After the destruction of Coast City, the subsequent insanity of Hal Jordan, and the destruction of the Central Power Battery, the Guardians decide to focus all of their remaining power into Ganthet. As such, he becomes the last Guardian.
Later, when Rayner briefly becomes the godlike Ion, he possessed more power than Hal Jordan did as Parallax. Realizing that he can not continue as Ion without losing his humanity, Kyle travels to the recently restored Oa to recharge the Central Power Battery.