Just found some things on Henry Hub and seems that is the key pricing point for the Eastern Region.
On "Source Energy" , is that a web site or ...????
This is only a very rough approximation.
Approximately three watts (or 10.239 British thermal units) of energy is consumed to deliver one watt of usable electricity. "
There is a big difference in the Ng required for a newer Combined Cycle plant and an older steam plant.
Have to look at the Gomex fossil fuels link yet.