Measuring Energy Consumption

Here’s a brilliant article that discusses and compares different ways of measuring energy consumption.  If I say I generated a gigawatt-hour of energy, does that mean the amount I sent to the consumer?  If so, and that energy came from a coal plant, I probably burned about 2.5 gigawatt-hours’ worth of coal, as the plants are about 40% efficient.   In other words, there was another 1.5 gigawatt-hours of energy that was converted into heat that was wasted in this process, but probably needs to be counted somehow. 

But what about renewable energy, e.g., solar PV.  Nothing is burned there, of course, so what do we do here?  As it turns out there are two equally correct answers:  We can either count the energy content of the electricity generated, or we can ask how much fossil fuel energy would have been required to produce the same amount of electricity. 

The author, Robert Wilson, does a really good job explaining a complicated subject.