Was going through http://en.wikipedia.org/wiki/Compressed_air_engine.
Wondering this technology can be used as range extenders in EVs or PHEV or RE - EVs. One of the good points i see is no pollution at all.
If these air engines offer constant RPM and get the required power to generate the electricity then this will be one of the ground breaking technologies.
The good part seems of PHEV/REEVs are:
1) They can be charged over night for daily needs.
2) For range anxiety needs the air compressed engines can be used.
3) On high speeds/Winds using aerodynamic designs the compressor can be re-filled.
4) With small air compressor/ Old gas stations , we can refill the air with in minutes.
Some of the engine designs looks very good (i like the Engineair one ).