economic and financial analysis ( Net Present Value)

Here are two cases studies, Ecuador and Chad , In ecuador Case Study there is a calculated NPV, i just want someone to break down the calculation and formulas used behind : Here is how they have done the analysis First, they have gathered historical data about consumption of energy in the countries (which they use to make forecast using techniques such as trend analysis or even available forecast in the case of chad) They have then identified potential project for gas flaring in each countries. They then calculate the technical cost (e.g cost of compressing , dehydrating, chilling and sweeting the gas. In other word gas treatment) and transportation costs of case from each of the project. Based on the foretasted consumption figure and the market prices of the gas, they then calculate (In dollars) the benefits that would be derived from each of the project They then calculate the investment required by each of the project.(This is based on available information ) So at the end, they have the 1) costs of each projects 2)Pontential benefits for each project 3) Investment requirement for each project based on this information, they are then able to calculate the NPV which they use to make recommendation.