What is the source of power for the Zeo Zords?

The Zeo Zords are powered by the Zeo Crystal.

In Power Rangers Zeo, the Rangers discover the Zeo Crystal after the destruction of the Command Center. The crystal leads them to the underground Power Chamber, where the former Mighty Morphin team receives a new source of power and becomes the Zeo Rangers. Their morphers and Zords draw on that same crystal-based energy.

The crystal is divided into five sub-crystals, each associated with one of the core Zeo Rangers. Tommy, Adam, Rocky, Tanya, and Katherine use the Zeo powers to pilot Zeo Zords One through Five against the Machine Empire. The crystal’s power is also connected to the Rangers’ transformation abilities, not merely to their giant machines.

The Morphin Grid is a broader concept in Power Rangers lore and can be associated with many teams, but it is not the specific answer used for the Zeo Zords. Energems belong primarily to Dino Charge, while “Power Crystal” is too generic and is not the canonical name of the Zeo power source.