Surprise Drop in Power Use Delivers Jolt to Utilities - WSJ.com

An unexpected drop in U.S. electricity consumption has utility companies worried that the trend isn't a byproduct of the economic downturn, and could reflect a permanent shift in consumption that will require sweeping change in their industry.
...
American Electric Power Co., which owns utilities operating in 11 states, saw total electricity consumption drop 3.3% in the same period from the prior year. Among residential customers, the drop was 7.2%. However, milder weather played a role.
...
Power companies are also questioning the reliability of the weather-adjustment models they use to harmonize fluctuating sales from quarter to quarter. "It's more art than science," says Bill Johnson, Chief Executive of Progress Energy Inc., Raleigh, N.C.

Environmental Capital - WSJ.com : Boxer’s Rebellion: Senator Lays Down 'Streamlined' Green Gauntlet

Citing New Mexico Sen. Jeff Bingaman, himself the author of a climate-change bill, The Vine figures simplicity might hold the keys to success next time around: “By contrast, Bingaman just wants to get the carbon-trading market established first, in a ‘streamlined’ bill, and worry about all the other stuff separately.”

But establishing economy-wide limits on greenhouse-gas emissions, and a market to trade those emissions rights, is a rather complex task in its own right.