(Adds quotes, cost of past storms, number of workers responding to outages)
NEW YORK, Sept 12 (Reuters) - Some 6.7 million homes and businesses in Florida and nearby states still had no power on Tuesday after the pummeling from Hurricane Irma, as utility companies scrambled to get the lights back on in one of the biggest power restoration efforts in U.S. history.
The total number of customers, representing about 13 million people, dipped from a peak of more than 7.4 million customers late on Monday. But some people in the hardest hit areas of Florida may have to wait weeks before they get power back.
Major utilities in Florida - including NextEra Energy Inc's Florida Power & Light, Duke Energy Corp and Emera Inc's Tampa Electric - have mobilized tens of thousands of workers to deal with the enormous power outages after Irma landed early Sunday and carved a destructive path up Florida, which has a population of about 20 million.
"This is likely to be one of the largest and most complex power restoration efforts in U.S. history, said Tom Kuhn, president of the Edison Electric Institute, an industry trade group.
More than 50,000 workers from across the United States and Canada were involved in the restoration efforts, including those from the affected companies and other utilities, Kuhn said.
Some Florida utilities, including FPL, had warned customers it could take weeks to restore power in the hardest hit areas.
However, the state's largest utility, FPL, said on Tuesday that would restore power to eastern Florida by this weekend, and to western Florida by Sept 22.
Irma hit southwest Florida on Sunday morning as a dangerous Category 4 storm, the second-highest level on the five-step Saffir-Simpson scale. It gradually weakened as it headed through the state, becoming a tropical storm and then a tropical depression on Monday.
Most of the homes and businesses still without power were in FPL's service area in the southern and eastern parts of Florida.
FPL said its outages dipped to around 2.8 million customers by Tuesday morning from a peak of more than 3.6 million on Monday morning, but that was still more than half of its customers.
In total more than 4.5 million FPL customers were affected by the storm, with over 1.6 million having their service restored already, mostly by automated devices.
RECOUPING RESTORATION COSTS
FPL said nearly 19,500 FPL employees and workers from other utilities and electrical contractors were working around the clock to restore power and rebuild the company's infrastructure.
It was too soon to say what the restoration would cost FPL, but in 2016, the company said it spent about $315 million to restore power after Hurricanes Hermine and Matthew, according to NextEra's federal filings.
Most of those costs were related to Matthew, which caused a third as many outages as Irma did for FPL.
To recover restoration costs, FPL files with state regulators and, if approved, adds a storm surcharge on the monthly bills of its nearly 5 million customers.
That surcharge was capped at around $4 per month for the average residential customer, according to NextEra's 2016 annual report. The company, however, said it could request an increase if storm restoration costs exceed $800 million in any calendar year.
Florida's second biggest power company, Duke, serving the northern and central parts of the state, said it still had about 1.2 million outages Tuesday morning, according to the company's website, while Duke's outages in North and South Carolina climbed to about 160,000.
In Georgia, utilities reported around 1.2 million customers without power Tuesday morning, down from a peak of more than 1.4 million on Monday night.
FPL said its two nuclear plants in Florida were safe. Both reactors at its Turkey Point facility, about 30 miles (48 km) south of Miami, remained shut early Tuesday, while both reactors at its St. Lucie plant, about 120 miles (190 km) north of Miami, were operating at full power. (Reporting by Scott DiSavino; Editing by Frances Kerry)