It has previously been proposed to store energy in the form of a liquified gas, such as liquid nitrogen or liquid oxygen. Either of these liquids or their natural mixture, liquid air, can be stored and transported in a well-insulated vessel carried on an automobile. Energy may be recovered from use from this liquified gas by three simple steps:
1. Pressurization of the liquid to a high pressure by pumping.
2. Vaporization of the cold liquid and heating of the gas with air from the ambient environment.
3. Expansion of the gas from high pressure to atmospheric pressure in an appropriate engine expander.
As noted above, the foregoing has been previously proposed, but the results are so poor that it is of little use of ordinary transportation. A heavy load of liquified gas is required for any reasonable range and the cost is unacceptably high. However, the system does have a number of favorable features including low pollutant levels, and the fact that hydrocarbon fuels are not directly consumed.
Accordingly, a principal object of the present invention is to improve the efficiency and range of automobiles and other engines operating on liquified gas, so that they are competitive with conventional internal combustion engines.