There are many problems :
$1.$ As pointed out by Olin, gas cannot exist as a gas at $0 K$.
$2.$ In ideal gases, interaction between molecules are absent. Hence, there is no potential energy. Remember that Potential energy always has an additive arbitrary constant.
$3.$ As pointed by Wojciech, you would need energy to cool that down to $0 K$.
I could have just commented about my point but I do not have enough reputation to comment. :P