Hi, I've been reading about compressed air energy storage and keep coming across that in 300 bar containers the achievable energy is 0.1MJ/L. Is this 0.1MJ/L of the volume of the air it is compressed to or of the total L of air that was initially used? (E.g If 1500L is compressed to 300 bar into a 5L cylinder will the total energy be 0.5MJ or 150MJ) I have been trying to work this out but cannot seem to come up with the the 0.1MJ/L value. Using the internal energy calculation U = 5/2PV I get 0.375MJ which is 0.00025MJ/L . (5L volume at 300 bar = 1500L total air. If I compress 1500L of air at 300 bar it can compress to 5L with total internal energy of 0.375MJ) Could someone explain how they worked out the 0.1MJ/L value and where I am going wrong? Thanks.