By Wayne Barber, Chief Analyst, Power Generation, Energy Central

Several trends seem to have emerged during the recent flurry of quarterly earnings calls by power generators.

For starters, it seems that everybody is talking about the weather. A milder-than-normal winter in many parts of the country depressed the usual level of electricity demand. Companies such as American Electric Power (NYSE: AEP) felt the impact on their bottom line. Duke Energy (NYSE: DUK) saw the lowest number of heating degree days on record in North and South Carolina.

Coal plants are especially affected by this weak power demand due to the combined of that and the allure of $2 natural gas that has gas units being used more. Southern Co. (NYSE: SO) for example expects 47% of its power to be sourced by natural gas in 2012 compared to only 35% from coal.