Liquid air and nitrogen are widely used in a variety of industrial situations and their use as an energy vector is an emerging application in the low carbon economy.
Cryogenic liquids have a number of benefits:
- The feedstock is superabundant (air) and none of the proposed technologies require scarce materials
- Storage is at low pressure and there is no fuel combustion risk
- A number of technologies servicing different scales of applications are being developed that could all use the same energy vector and share infrastructure
- Cryogenic liquids are already produced and distributed in huge volumes around the world, thereby inexpensive to introduce
- The energy density of liquid air compares favourably to zero-emission competitors
- Very fast re-fuelling times are possible compared to other zero emission technologies
- Marginal cost of additional energy storage is very low through increased tank size
Cryogenic liquid has a number of advantages over compressed air including:
- The energy density of cryogenic liquids is much higher. Compressed air would have to be stored at 500 bar to have a comparable theoretical energy density to the practical availability of a cryogenic liquid stored at ambient pressure.
Insulated vessels are cheaper than re-enforced high-pressure vessels