To enable demand-side energy management and renewables integration via a novel green energy storage technology

Energy Compression Inc. is a clean-tech startup company in the greater Boston area specializing in thermochemical (as opposed to electrochemical) energy storage. Thermochemical processes convert heat (thermal energy) and/or work (mechanical energy) into chemical energy of various kinds. Since heat and work are readily generated from electricity and vice versa, thermochemical energy storage can serve as a direct substitute for batteries. It is generally more cost effective, nevertheless, to use thermochemical processes to store forms of energy that are already in use at the site of installation.

In air conditioned buildings, for example, storing the cold needed to chill the air is just as valuable as storing the electricity needed to run the air conditioning (A/C) equipment. This is known as cold thermal energy storage (CTES). This is most often done today using either chilled water or ice as the cold storage medium. The former requires large tanks for the chilled water, for which there may not be adequate space, while the latter requires temperatures below those needed for A/C, and so is less efficient. Energy Compression is developing thermochemical alternatives that combine the compactness of ice with the efficiency of chilled water. The resulting product should also be easier to install as a retrofit to existing A/C equipment.

Another example is found in factories that use large amounts of compressed air to power pneumatic machinery, where storing the air is just as valuable as storing the electricity needed to run the air compressors.

We call it Clathrate-Hydrate Cold Thermal Energy Storage (or CH-CTES for short). CH-CTES is not only very different from electrochemical batteries and capacitors, but is also quite distinct from conventional implementations of cold thermal energy storage, most of which use either chilled water or ice as the cold storage medium.

The most important differences between conventional CAES and AE-CAES are:

  • Whereas existing CAES plants store their air in underground caverns, aquifers or salt domes, AE-CAES plants can be located anywhere
  • Although conventional CAES could also be located anywhere by using high-pressure storage tanks, AE-CAES uses much lower pressures and hence less costly tanks
  • Whereas existing CAES plants burn fossil fuels (to recover the stored energy cheaply, efficiently and at a high power level), AE-CAES can be fully carbon neutral
  • Although several carbon-neutral (“isothermal”) implementations of CAES are under development, the low and constant pressures used by AE-CAES allow efficient compression and expansion with off-the-shelf hardware
  • The proprietary air and energy storage system used in AE-CAES is intrinsically fail-safe, and would not explode even if shot full of holes with a machine gun
  • Together with the fact that all the materials utilized are environmentally benign, this makes AE-CAES ideal for distributed energy storage on the customer’s side of the electricity meter