How many new residents does Florida expect in the next ten years and how much more energy will they use?

These are some of the questions Florida Power & Light addressed in hundreds of pages of documents it sent to regulators last week to support its request to dismantle four power generators at its Port Everglades plant in Fort Lauderdale and build a new, more efficient plant.

The $1 billion project would produce 1,277 megawatts of power, or 7 percent more than it currently provides, and it is projected to save customers $425 million to $838 million over three alternate ways FPL explored to produce more energy, according to the utility.

FPL reported:

New population projections are showing a slower growth rate in Florida than previously forecasted. This summer, the state Legislature's Office of Economic and Demographic Research decreased Florida's estimated population in 2021 10 percent from 2.7 million to 2.4 million, according to FPL documents to the state Public Service Commission. Still, the Office projects Florida's population from 2011 to 2021 will grow by about 13 percent instead of the 14 percent it previously projected.

Floridians will save a lot more energy in the coming years. A consultant for FPL projects a 148 percent increase in annual energy conservation from 2011 to 2021 to 3,365 megawatts by 2021. The projection doesn't include the impact of utility-sponsored programs to encourage lower energy use. In late 2009, regulators beefed up FPL's energy saving goal to 2,878 gigawatt-hours over nine years. This year, they backtracked, slashing the goal over that time to less than a third because of concerns about the cost of energy-saving programs.

FPL customers will collectively need 20 percent more power by 2021. That represents an increase of 21,900 gigawatt-hours. That's in part because FPL projects 14 percent more customers from 2011 to 2021, economic growth projections for the state, and other factors such as the increased use of electric cars that need to be powered up, according to documents FPL filed to the PSC.

FPL will also need the additional power because it won't produce as much power as it normally does during times of year when electricity demand is highest. In its request this year to more than double the size of a 63-megawatt waste-to-energy plant in Palm Beach County, FPL said it plans to turn power plants off to do planned maintenance work more often during high-demand months. PSC employees had questioned the need for doing that "given the company's generating fleet in 2011 is largely unchanged from" the year before when its projections did not factor in doing more maintenance work during high-demand months.