Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.
Energy storage is becoming an issue in a world were
renewable energy will probably be the major way of energy
production.
Liquefaction of gasses in order to store the liquid is being
looked at. This liquid can then be expanded in a Rankine cycle
in order to recover the energy. If waste heat is used as input for
the boiler, this can be an interesting technology to raise energy
efficiency in industry.
In this paper an analysis is made of the efficiency of storing
liquefied air. Starting from the thermodynamics of the basic
cycle, more complex combined cycles are studied.
It is clear the ideal cycles have a good efficiency. Taking
real expander efficiencies into account reduces the output a lot.
Using combined cycles for liquefaction and energy production
do not raise efficiency in a significant way.
Conversion efficiencies are in the order of 20 to 50% ,
making these cycles comparable to hydrogen storage and
compressed air storage.
