The most ambitious solar plant in Florida has 190,000 mirrors that reflect sunlight onto tubes filled with 1.2 million gallons of oil-like fluid that heats to a blistering 740 degrees.
Built by Florida Power & Light, the plant is a complex and expensive foray into breaking the state’s dependency on oil, coal and natural gas. But after three years in operation, the plant is making less power than expected.
Blame rainy weather, says FPL.
Unique in the way it works, the $398 million solar plant in Martin County near Lake Okeechobee is billed as having the ability to churn out as much power as consumed by 11,000 homes.
Performance in 2011 was terrible, partly because of a disastrous leak of the oil-like fluid, and by year’s end only enough electricity for 2,000 homes was generated.
The next year showed improvement, with a power output enough for 6,160 homes. FPL officials said they were getting the hang of the plant and predicted better results in 2013.
Only that didn’t happen; The year came to a close with the plant making enough electricity for 6,050 homes.
FPL Spokeswoman Sarah Gatewood said the plant didn’t have operational problems but last summer was cloudier than normal, cutting down on the sunlight hitting the mirrors.
The plant’s mirrors cover a combined space of 80 football fields; They concentrate sunlight onto a surface area about the size of a single football field. Energy levels drop dramatically when clouds cast shadows on the mirrors.
FPL officials say the plant is built to last 50 years and attempts to boost its performance will be ongoing.
Energy experts defended the solar plant as a needed exploration into a form of energy that doesn’t pollute like coal, oil or natural gas.
Jim Fenton, director of the Florida Solar Energy Center, said FPL’s decision to build the plant was sound. At the time, solar thermal plants like FPL’s were less costly than those using solar panels, which turn sunlight into electricity.
Since then, the cost of solar panels has plummeted, with China playing a key role.
Also working in FPL’s favor, Fenton said, was the decision to funnel steam from the mirror-based plant to an existing power plant, one that uses natural gas. Doing so meant FPL didn’t have to invest in a stand-alone generator to harness the solar plant’s steam.
“With the first of anything there are a lot of lessons learned,” Fenton said of the plant. “It’s still better than the coal plant down the street.”
Yogi Goswami, a University of South Florida professor and expert in solar energy, said FPL has taken a necessary step pioneering solar energy in Florida.
And, he said, solar thermal plants, including those in Southwestern states, have potential to overcome the inability of solar to generate energy after the sun goes down.
Goswami said batteries of the size and capacity to be useful to a utility are years from reality. But solar thermal systems, he said, can store energy in the form of heat.
FPL’s plant doesn’t store a lot of heat; the oil-like fluid remains hot for an hour or so after the sun no longer hits the plant. But other plants can use molten salt to store enough heat to make electricity when it’s needed most, such as early morning or late afternoon, Goswami said.
“As their quantity and the capacity increases, and more investment goes into them, their prices will tumble,” Goswami said.