Energy, Information, Psi, Qi, Chi, etc. is the general term for a "metaphysical" (not to be confused with physical energy) something, that can be controlled with your mental mind and accumulated. The accumulation is mostly done between the hands, like the creation of the psi-ball, where you accumulate and compress the energy at one point between your hands. It's unclear whether it's a "beam" or something other shaped. Generally, the most part of the community agrees to, that energy is simply a vibration (maybe 0/1-dimension line?) that can be accumulated to a shape. Lastly, the definition of energy generalizes all other terms, which are looking like as they were different from each other, which certainly isn't true.
Many, many confusions are happening around this term. Since the term "energy" was used, a lot of skeptics confused this with the physical energy. Of course, it will not make any sense if you say, that you simply control physical energy, however you do it indirectly. Energy in physical terms means something, that expands. Ex.: You touch metal, your heat of your hands are getting transferred to the metal. Effect: The metal's temperature is increasing. However, physics does not differ in expansion and contraction. So, physics says, that also "cold" things are transferring their cold energy to the target. Now you could say, that the cold metal object simply "absorbs" that heater energy of the target object and therefore it gets cold instead of transferring. Now, where's the solution? The term "increasing" is what refers to "energy" in physics! In metaphysical definition however, the energy is NEITHER increasing nor decreasing. It's most likely doing BOTH! In this case, metaphysical energy is simply vibrating energy. In hermetic references, in Franz Bardons metaphysical system, it's also called: "electromagnetic fluid", which is in it's effect also contractive and expansive, short for: vibrating. Through accumulation and concentration of this energy, you can change that vibration and therefore create a characteristic for this accumulated energy. This means, that a special vibration of the energy gives it's general characteristic like "cold" and contractive.
What does energy look like, what exactly is it? Edit
Energy isn't something you can see, taste, smell, hear or feel. If you are able to see the energies, (through third eye) then you don't really see the energy itself. What you see is the vibration of that energy! And the more you get a feeling of it, the more you know what vibration stands for what characteristic property of the energy. It's not really easy to simply remember that vibration through seeing it. So, psionics more likely remember the colors the energy gives out or their movements. People, which are practicing clairaudience, are remembering the sound of the energy. In summary, everything we feel about energy, is not really the energy itself. What we actually feel, taste, hear, see or smell is the vibration of the energy.
Energy Control Edit
There are many exercises on how to control and learn to accumulate energy. You can accumulate the energy everywhere and at anytime. You can accumulate it "onto" your body or inside your body. Known beginner exercises are simply energy grounding, energy control or the all known psi-ball exercise.
Energy Alchemy Edit
Energy alchemy is more likely the study of "known" and general energy vibrations. The four general are: Expansion, Contraction and Expansion-Contraction (In one) In hermetic references also called: electric fluid, magnetic fluid and electromagnetic fluid. Expanding that process, with the primal qualities: Heat, Cold, Wet and Dry. Although wet stands for something round, light. Dry stands for something edged, heavy. Using those primal qualities, we get the "hermetic" elements, which shouldn't be confused with the physical elements: Fire(Primal qualities are Heat and Dry + Electric Fluid), Water(Primal Qualities are Cold and Wet + Magnetic Fluid), Air(Primal Qualities are Heat and Wet + No fluid/electromagnetic neutral fluid), Earth(Primal Qualities are Cold and Dry + Electromagnetic Fluid).
Energy alchemists are working with the electromagnetic fluid (the vibration) and study most occurring vibrations. Through this, analogies can be created and some create complex formulas (through Kabbalah(or Quabbalah) or general mathematical methods, in case the energy alchemist is knowing maths) to combine those energy vibrations to get the best vibration out of it.