An illustration helps. Suppose you are building a power plant that could receive coal by truck, train, or water. Power plants are long-term investments with operating lifetimes of 50 to 75 years. Whether you're a deregulated merchant utility or a regulated utility, you have to show either your lenders or the state regulators a pro forma that projects operating costs into the future. Both are looking for the same thing, that the coal plant will be the lowest-cost power producer not just the year it is built but 30 years from now, the one to protect the interests of the stockholders of the bank, the other to protect the interests of the ratepayers of the state. If the coal plant 20 years from now is no longer the low-cost power producer, then someone will build another plant to sell at a lower cost and idle your plant (causing you to default on your note), or the ratepayers will be stuck with higher utility costs than they should. Either way, a fiduciary irresponsibility has occurred.
The overwhelming operating cost of a coal-fired utility is the coal delivered to the plant, and the coal transportation is often much more costly than the coal itself. So when you're creating your future costs, one method is to phone up the truckers, railroads, and barge lines and ask them to project their costs 30 years into the future. You could take that to the bank or the regulators, and after they pick themselves up off the floor, they'll send you home to try again. The better method is project your own costs. To know that, you have to know their fuel cost, and their fuel use trends, and the fuel price sensitivity. You also want to know all this to be able to project what sort of regulatory trends are going to affect you. For example, you know that Congress is talking about cap-and-trade restrictions on CO2, so you had better project what kind of affect such a thing might have on your transportation costs. Because your lender or regulator will ask you about the possible effects this might have on you, and "I have no idea" is not a very good answer.
In short, if you are making a $6 billion bet with someone else's money, be prepared to spend a few million dollars becoming an expert on fuel efficiency of transportation modes, or hiring experts, or both. A coal-fired generating station is admittedly an extreme case as it is expensive and long-lasting. But even a distribution center location for a big-box store will look very hard at future fuel prices and the regulatory environment, in order to make the internal and external (bank and stockholder) case to build the DC here versus there.