Getting this error:

Failed to load mods: Error while loading entity prototype "gas-power-station-1" (generator): Surface conditions are disabled and can not be used. Surface conditions require space-travel.
Modifications: Tiered Gas Generator

Guess this mod only works if you have Space Age now?

No, there is a condition which will set the surface condition if the space-age mod is enabled.
I've changed the way the key insertion is done.
I've tested both ways and they worked for me. Let me know if this works for you now.

It works, thank you.