FPL’s concentrated solar energy stars shine at new 500-acre array

Armed with sponges and water, Florida Power & Light Co. workers finished cleaning the mirrors at its new Martin County solar-thermal plant this week, all 190,000 of them.

With 150 people, including Gov. Rick Scott, expected for today’s dedication of the one-of-a-kind hybrid Concentrating Solar Power center, it’s nice that the 5-by-5-foot mirrors will be their shiniest. But the cleaning that took four months was not for cosmetic reasons.

Secured in 6,800 aluminum frames on 7,100 steel pylons in perfectly straight rows on 500 acres, the mirrors are the stars of the company’s Martin Next Generation Solar Energy Center west of Indiantown. Their purpose is to generate energy. They work best when dust-free .

"We are taking the sun’s rays and concentrating them 80 times," said John Gnecco, Juno Beach-based FPL’s director of project development at the solar field this week.

The $400 million plant with a peak capacity of 75 megawatts began operating with its seven employees in November. It’s the world’s first Concentrating Solar Power plant directly connected to an existing combined-cycle natural gas power plant. It generates enough electricity to serve 11,000 homes, just one-fifth of 1 percent of the power the utility’s 4.5 million customers use.

The plant, which came in $75 million under budget, wasn’t just a matter of setting up mirrors.

"Everything was assembled on site. It’s like a big Lego set," Gnecco said.

The plant joins FPL’s 25-megawatt solar plant in DeSoto County and 10-megawatt plant at the Kennedy Space Center.

Although solar takes more land than other types of power plants, it was workable because FPL owned the remote 11,300 acres where it operates five generating units.

FPL sister company NextEra Energy Resources built its first solar plant in California’s Mojave Desert. At 310 megawatts, it is the world’s largest and oldest. Building solar in a hurricane zone is different.

"We had to temper the glass," Gnecco said.

Although 150 Florida companies were involved in project, the only firm with kilns large enough for the tempered glass is Rioglass Solar, based in Madrid.

In the desert, solar mirrors are bolted down in four places, but at the Martin plant, they are bolted in nine spots, using a total of 1.7 million nuts and 4-inch bolts.

The mirrors rotate to follow the sun, moved by hydraulic motors and monitored by computer operators in a control room.

The sun’s energy is beamed into glass-covered piping, heating synthetic oil to 740 degrees. The fluid flows to the solar steam plant. There, the heat boils water.

"Boiling water is all we are doing," Gnecco said. "We take that steam and convert it to mechanical energy through a steam turbine."

Eric Silagy, an FPL senior vice president, said that 2008 legislation allowed the company to build its 110 megawatts of solar. Since solar plants are more expensive to build than other plants, more legislation is needed allowing FPL to recoup costs, he said.

FPL would like to build an additional 300 to 500 megawatts of solar.

"We believe that solar is a great addition to the fleet at FPL," Silagy said. "We are the Sunshine State. We have proven that it works very well."

Jim Murley, an assistant dean at Florida Atlantic University and chairman of the Florida Energy and Climate Commission, said the state needs more renewable energy, which can include biomass, wind energy and solar power.

"Florida is fortunate to have a corporate entity that is capable of building and managing these kinds of solar facilities," Murley said.