They do require a lot of extra power to keep them online. The Surface to Air Missile Site is Nod's primary defense against flying units. The Missle Silo allows Nod to launch the cluster missle or chemical missle. The Obelisk of Light is an extremely powerful weapon for base defense. It has a huge powerful beam that stop the enemies heaviest units.
Few units survives a single shot.
The Stealth Generator requires a lot of power to keep everything cloaked. The mysterious Temple of Nod allows the Nod player to access advanced units like the Mutant Hijacker and Cyborg Commando. The Hunter Seeker Drone also becomes available. The Tiberium Waste Facility stores Tiberium Veins for adeadly purpose. Once the Weed Eater unit returns with enough Tiberium Veins the are process and loaded into a chemical missile.