A note on units.
A joule (J) is a measure of energy. Raising an apple about a meter requires you to expend about one joule of energy. A watt (W) is a measure of power - the rate at which energy is expended - if you slowly lift the apple so it takes a second to lift it through a meter, the whole time you will be expending power at a rate of one watt. A petajoule (PJ) is 1,000,000,000,000,000 joules. That is enough energy to run 10,000 average Canadian cars for a year.