Time for another one of my bad suggestions.
You pay 50 CE and you buy an empty Mist Tank. You expend 100 Mist Energy to fill this tank. You have a full Mist Tank. It's NOT tradable/sellable/giftable.
You use the Mist Tank, you get 100 Mist Energy and the tank is used up.
I am sure there is something bad about this. What is it?
Actually I think this is a pretty sound idea.
However, I don't think SK would enjoy people using up their daily ME doing this instead of crafting.
They don't want people saying they have 500 ME to spend on the clockworks because they didn't play for 5 days.
X_D