It's like saying gas at the pump costs you $3/gallon but building a storage facility costs $100/gallon. Yes, they're both $/gallon, but these aren't the same measurements--one is for a gallon of dispensed gasoline and one is for constructing storage with the physical capacity of a gallon. One is the price of gas and the other is the price of storage. You can store and then dispense many, many gallons over the lifetime of that one-gallon storage.