The Storage Module allows the base to store larger quantities of Helium-3 and Mineral Ore.
— In-Game Description
Storage modules are used to store player's Helium-3 and Mineral Ore. Note that they do not store any Antimatter. If you are attacking a base, you can target and specifically destroy these base modules to steal additional resources.
Destroying combat modules yield no resources, destroying resource miners can provide minimal amount of resources, destroying their Bridge also yields resources and medals. Player fleets can steal resources up to five times their maximum storage capacity.