Energy Compression, Inc.

AE-CAES uses nano-porous materials to adsorb air. This not only frees it of the geographic constraints of underground CAES facilities, but also: greatly reduces the cost of the air storage tank and other hardware, makes the system intrinsically safe as well as environmentally benign, and allows it to store substantial amounts of cold in parallel with mechanical energy. The best-known adsorbents for air are the zeolite minerals. The amount of air in a tank filled with a zeolite depends exponentially on its inverse temperature, rather linearly as with an empty tank. This makes it practical to operate the system at an essentially constant pressure by cycling the temperature instead. At modest pressures of order 10-20 bar, the combination of an adsorbent with a “temperature-swing” cycle greatly reduces the volume of the air storage tank needed to hold a given quantity of air. A low and constant pressure also lowers the cost of the compression and expansion hardware needed for CAES.

AE-CAES can attain a acceptable power density using 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. The zeolite will be cooled to subfreezing temperatures to fully charge the system with air, so the system also store cold in concert with mechanical energy, which can further enhance its value.