Any time you see "energy_damage = X" in any FL coding, it's shield damage.
I'm not sure of a mod that has it so you can damage someone's power supply. That's an entire different kind of coding.
And as for regenerating shields -
[ShieldGenerator
nickname = shield02_mark09_hf
ids_name = 263837
ids_info = 264837
DA_archetype = equipment\models\st\li_refractor_shield.3db
material_library = equipment\models\li_equip.mat
HP_child = HpConnect
hit_pts = 6752
explosion_resistance = 0.500000
debris_type = debris_normal
parent_impulse = 20
child_impulse = 80
volume = 0.000000
mass = 10
*****regeneration_rate = any positive number*****
max_capacity = 6050
toughness = 60.500000
hp_type = hp_elite_shield_special_9
offline_rebuild_time = 12
offline_threshold = 0.150000
constant_power_draw = 0
rebuild_power_draw = 10
shield_type = S_Molecular01
shield_collapse_sound = shield_offline
shield_rebuilt_sound = shield_rebuilt
shield_hit_effects = 0, gf_pi_shield01
shield_hit_effects = 100, gf_pi_shield02
shield_hit_effects = 500, gf_pi_shield03
separation_explosion = sever_debris
LODranges = 0, 20
lootable = true
This is the coding for a random shield i scrolled down to and selected.
The line in the code where it states "Regeneration_rate = whatever" This absolutely must be a possitive value, and it cannot be added to anything else as far as my testing is concerned.
Me and a friend had an idea, instead of the Nomad's having Hull, they had instead an organic hull, or one that regenerated slowly.
However, no matter how we set it up, it never worked, and even with that line in it didn't work.
"regeneration_rate = "
"hull_regeneration_rate = "
So, my theory is taking this line and adding it to a nebula, will not give you added shield reeneration.
And as for the -100 in theory giving you shield regen, sorry for that but that has the same effect as -1.
Any negative integer instantly kills anything!
We tried exstensivley to make "Repair" turrets that only Repair ships could mount, they had a very short range and lifetime however, in theory it should have "healed" a damaged ship.
The result was 1 shot instantly killed a player battleship with 4,000,000 hull, and the "hull_damage" was set to -200 in the weapon coding.
So, adding energy_damage inside the coding of any zone, not just nebula, cause you must take into account that there are zones with radiation that aren't nebulas.
In theory, this should work and it should do shield damage.
However! you must remember, that it would have to do more than the shield can recharge.
So for example
In the unmodded FL, and most mods, NPC shields have a regeneration of 1
While the best player shields are in the hundreds.
So, if you make the energy_damage less than what the shield can regenerate per second than it will have no affect on the player, and the zone or nebula will become an NPC slaughtering ground.
But as for the power damage
But this is jsut my outlook on it.