Worldwide transport sector alone releases billion tonnes of excessive carbon dioxide in the atmosphere through tail pipe emissions thereby causing serious threat to global warming. It is also leading to fast depletion of hydrocarbon fuel. On account of such challenges, continued researches are being carried out to supplement the energy by renewable resources and alternate energy to sustain hydrocarbon fuel. Now a days the major thrusts are being laid upon the utilization of wind energy, hydropower, tidal and nuclear power generation. Simultaneously efforts are also made towards storage of the energy and appropriate conversion system and its better utilization. This paper focuses on study of some energy storage and energy conversion systems. Special focus is laid on use of compressed atmospheric air as a viable alternative energy source. Such energy storage system can be used as clean energy source as zero pollution sources, and help in mitigating the global warming.