adsorption, compressed air, energy storage, Zeolites
Adsorption-Enhanced Compressed Air Energy Storage (AE-CAES) uses nano-porous materials to adsorb air. The use of an adsorbent changes the effective equation of state for air, so that it becomes possible to operate the system at an essentially constant pressure by cycling the temperature instead. This greatly reduces the volume of the air storage tank needed and so allows the use of much lower pressures than have previously been seen as practical for CAES. A low and constant pressure greatly reduces the cost of the hardware needed for non-underground CAES. In addition, the release rate of adsorbed air is intrinsically limited, which together with the low pressure makes the system essentially explosion proof. Even though much more heat must be moved around over course of the storage cycle than in conventional CAES, AE-CAES needs only heat at much lower temperatures. This allows it to use cost- and carbon-free waste or solar heat to make up for losses, rather than high-temperature heat from burning fossil fuels as in existing CAES systems. As a result, an AE-CAES system can be economically efficient even if it is not efficient in the strict physical sense of the word.