From Planetside Syndicate
NTUs are consumed by the base when repairing damaged systems such as the generator, Respawn tubes, terminals, and Phalanx wall turrets. If the NTU level of a base falls to 0%, the facility becomes neutral. The level must be raised above 0% for a successful recapture.
Nanites make up what we know as Warpgate Energy. It is through these particles and the way they flow through the gates that everything within Auraxis is sustained, created, and recreated.
By interpreting these energy flows, Empire scientists are able to make equipment, vehicles, structures, and even humans appear and dissappear like magic.
No one really knows what they are, only that we can manipulate them to our own ends.