The key issue is that energy storage in the form of compressed gas is not efficient enough. So one has to haul around large tanks, which are heavy so they reduce efficiency. Even if you liquified the gas it will not be much better.
The positive side is that one could use solar energy to power a compressor and compress the gas 'fuel' more or less for free. You could even use a Tesla turbine as the engine and have no moving piston parts at all, just a set of spinning discs.
The key issue is that energy storage in the form of compressed gas is not efficient enough. So one has to haul around large tanks, which are heavy so they reduce efficiency. Even if you liquified the gas it will not be much better.
The positive side is that one could use solar energy to power a compressor and compress the gas 'fuel' more or less for free. You could even use a Tesla turbine as the engine and have no moving piston parts at all, just a set of spinning discs.