How much energy is 1 Megawatt?

First of all, a megawatt is not a unit of energy. It is a unit of power, or the rate at which energy is used. 1 watt corresponds to 1 joule per second. For example, a sixty watt lightbulb uses 60 joules of energy per second. So a megawatt is one million watts, or one million joules of energy per second. Electrical energy is often measured in kilowatt-hours by the electric company (So that they know how much to charge you). This is equivalent to the amount of energy that a kilowatt power source could supply in one hour. The amount of energy in joules that a kilowatt hour is goes as follows: 1 kilowatt = 1000 watts, so 1000 joules per second. Multiply this by the number of seconds in an hour, and you have 3600000J.