The basis for most high end Varden tech, is Xychorium. This crystalline material is created by an Matter-Energy Converter, as no natural sources are known, and it seems nigh impossible to create even a bit of it with traditional methods. The crystal is capable of absorbing tremendous amounts of energy, in the form of heat, without melting, or otherwise destabilising. When exposed to specific effects, this process is reversed, and the stored energy is released from it. The amount of energy a crystal can handle is unclear, as the casing and cabling of these heat cells are destroyed before the crystal would be overloaded. When this happens, the crystal simply melts its way out of the heat cell in whatever direction the surrounding forces pull it. To prevent this, more advanced (and larger) cells make use of built-in gravity generators to keep the crystal locked in the cell for longer.
These heat cells consist of an armoured outer casing, a highly reflective inner coating, the crystal in the middle, in almost perfect vacuum, and the energy tap. This tap is currently the limiting factor for the output of heat cells, as they are not as resistant to heat/energy as the crystal itself.
These cells are often used in pairs. While one powers equipment, the other charges, absorbing the waste heat created in the process. This is especially important for the energy efficiency of equipment like capital ship class weapons, null-drives, and the like.