The are always at least 2 scenarios when you have a project. You have the money or you don't. If you have the money, you have to take into account the opportunity cost of that money. If you have to borrow the money for the project, then you must take into account the interest charged by the loaner.
These costs are usually taken into account in your hurdle rate or discount rate. Your hurdle rate will likely be higher if you must borrow your project money. For more information go to hurdle rate
