like farms/silos in warcraft / starcraft
Not quite sure how this well this would work, but figured it was worth discussing :)
I think that all marine buildings should have a power upkeep cost to them, and that powernodes actually generate upkeep power.
e.g. the armory has a power upkeep cost of 5, and each powernode provides say 30 power. (obviously numbers would need tweaking, but enough to build the essentials as well as make a start on a particular strategy).
Then if the commander realises that he needs lots of turrets, then the marines would need to secure another power node to get an additional 30 upkeep power.
Additionally to make things even more interesting the amount of excess upkeep power you have could speed up research and or build times, which means that if you go light on buildings you and have secured many locations you could fast track your way to an end game weapon.
This could add an extra management element to the game. it also means teams that turtle too long are at a disadvantage and that end game could happen a bit more smoothly, since securing only one location on the map means you are quite limited to how many structures you can build at any one time.
It also means that marines would be encourage to collect the powernodes on the map which do not have a resource tower next to them. (like the one between datacore and reactor on ns2_summit).
The same thing could go for alien team, but it would be measure on infestation coverage perhaps. (the more infestation the more buildings you have and the faster things happen). Or the amount of cysts covering a unique area (%of cyst not overlapping = more upkeep power)