Liquid air power

[MarkP]

The Tata car mentioned does not use liquid air, only compressed air. I have no gut feeling about how efficient liquifaction of air would be. I do know that you have to take a massive amount of heat out to make air condense and we are talking about cryogenic temperatures. All this is different from plain old compressed air. In a sense the liquid air would be much better because you would be operating like a steam engine but instead of burning coal or oil to make water boil, you are using the ambient heat from the environment to make liquid air boil. Somewhere there must be very big engines and radiators to make all that heat flow uphill, so that later you can reap the benefit as the heat flows back downhill from the ambient air to the cryogenic air.