The Thaumonomicon page "Advanced Essentia Storage", is on the Eldritch Tab, so it can only be researched after the Eldritch Epiphany. This research gives the player the recipe to create the Essentia Reservoir, a powerful container for essentia.
Purpose of the "Essentia Reservoir" Edit
Similiar to warded jars, essentia can only be received or drained from one side, but unlike the jars, the block's connection can face in any direction (and be changed with the wand). A special feature is that, like buffers, the reservoir is able to store 2 or more essentia types. The Essentia Reservoir can store a total of 256 points of essentia total, in any combination of aspects.
Reservoirs cannot be drained or filled by hand (right-clicking with or without jars, or glass phials). Golems can work with them, but with some limits -- they are treated as non-jar devices, so they have priority over jars and the golem may ignore other marks if filling a reservoir. The Infusion Altar (or essentia mirrors) will still drain essentia out of the reservoir just like it would for warded jars. A further complication for using them in piped systems is that they only have 24 suction, so almost anything else can drain them unless buffers or other protective measures are used.
Caution: Breaking the essentia reservoir that contains essentia will cause a leakage of flux gas and goo, and likely an explosion. The more essentia held, the more flux, and the bigger blast. They can be emptied easily and safely by an essentia crystallizer. If the contents need not be saved, void jars can empty out one aspect at a time.
Middle Item: Essentia Buffer
4x Warded Jar
2x Voidmetal Ingot