ghosta,
I am not sure I understand you very well. Are you talking about a specific physical effect? Bose-Einstein condensation?
It is true that very cold matter (near absolute zero, -273 C) is less reactive - electrons hop to lowest states, mechanical vibration *almost* siezes. Latest work does, however, say that some movement exist. While it is true things like radiation are effetively "turned off" at low temp, it does not appear to me a good way to store energy. Reasons are two:
1. Thermodynamics: cold things want to get warm, warm things want to get cold, all wants to be uniform (result of second law of thermodynamics). So, the business of keeping things cold is very, very energy-costly.
2. Conservation of energy: say you have cold gas... If you want to heat that same gas, than somehow extract energy from it...you still have to heat the gas, which costs energy. So, you have to *give* the energy before you can *take* it. And since nothing is 100% effective, you will loose a bunch in the process. My gut tells me electromagnetic or chemical storage is better than using temperature of gasses.