I was reading this article about different types of energy storage, and it gave this formula for compressed air. Joules = P0V0ln(P/P0) Where P0 = Atmospheric pressure 105 Pa V0 = Volume of air to be compressed in m3. P = Pressure in tank when compressed in Pa. Note: This formula is for Isothermal storage. The reason for this post is because I want to make sure I'm understanding this formula correctly, and because I want to know if this formula is valid at all pressures. I'm guessing it's based on the ideal gas law, and at some pressure it starts to break down, but I don't know if that's true or at what pressures it becomes an issue. I don't know that much about this topic so I decided to ask here. Thanks.