Water hog: Okeechobee power plant to use 9M gallons daily
Florida Power & Light is planning to pump a staggering 9 million gallons of water per day out of the same aquifer that supplies most of the drinking water for Indian River County to cool and generate steam at its huge proposed power plant in Okeechobee County.
Indian River County gets most of its water from the upper Floridan Aquifer, using about the same amount as the power plant, 9 to 11 million gallons a day.
Concerned about possible impacts on the water supply, the county enlisted the aid of St. Johns River Water Management District to ensure its water source is safe. The water district added provisions to the power company’s water-use permit at the county’s request.
“You will see that we place conditions on the applicant [such as using the lowest quality source of water and ensuring withdrawals do not negatively impact others in the area]. If the request were a threat to the county’s potable water supply, the permit would not be issued,” St. Johns River Water Management District spokesman Ed Garland wrote in an email.
FPL applied last September to construct and operate a natural-gas-fired generating plant on 2,800 acres just across the Indian River County line in Okeechobee County. It will provide 1,600 megawatts, enough to power 300,000 homes for about 744,000 people, FPL spokesman Dave McDermitt said.
As power plants go, Florida Power & Light’s Okeechobee Clean Energy Center will be one of the more energy and water efficient in the world, McDermitt said. But it will still be a water hog.
It is in such a remote area it can’t reuse treated waste water from a county or municipal source, as many power plants do to conserve water throughout the U.S.
McDermitt said the site was chosen because Florida Power & Light already owned the 2,800-acre property, it’s close to power transmission lines and it’s convenient to State Road 60. There is also room to put up solar panels in the future, which don’t use water.
The power plant will use an average of 9 million gallons a day, but sometimes up to 11 million gallons a day. The water district capped upper Floridan Aquifer withdrawal to 9 million gallons a day, forcing the company to find an alternate water source for times when usage is greater.
At the county’s request, the water district permit stipulates the power plant must study a water source coming online in about five years, the Grove Land Reservoir and Stormwater Treatment Area, which is about 8.5 miles southeast of the proposed plant, on land owned by Evans Properties.
McDermitt was vague when asked if Florida Power & Light has done anything so far to determine the viability of this alternate water source. “We are committed to give full consideration to any new water source that may be available during the operating life of the FP power plant,” he said.
County Commissioner Tim Zorc, who took the lead on studying the power plant’s possible impacts on the county, said Florida Power & Light would have to pay the private owner for water use, acknowledging this alternate water source would be more expensive.
At the county’s request the water district also added a provision requiring that the power plant wean itself off upper Floridan water over a seven-year period, beginning in 2021.
The power plant will use seven wells to begin with, one existing and six new ones, all drilled to the depth of the upper Floridan aquifer. The permit requires the power plant to drill deeper, into the Avon Park Permeable Zone, replacing one well per year from 2021 to 2028. The Avon Park water is lower quality, having more particulates, which makes it less desirable for plant cooling, but there are several geological layers separating it from the upper Floridan, ensuring the county’s superior water source is preserved.
However, the permit is written in such a way that the power plant can continue to use the upper Floridan if the Avon and other water sources prove too poor in quality for efficient plant operation.
The power plant is designed to cycle each gallon five times through the system, the water becoming more concentrated with particulates due to evaporation with each use. If the water starts out with a higher concentration of particulates, it won’t be usable for the five cycles. Also the pipes and workings of the plant could corrode or get gunked up by sulfur and other particles in lower-quality water, undermining energy efficiencies and forcing the use of more water, defeating water conservation goals.
Therefore the permit forces the power plant to search for and prove the usefulness of alternate water sources, allowing it to fall back on the upper Floridan if they are not “economically, environmentally, or technologically feasible,” which is a standard requirement of the water management district.
Asked why the plant doesn’t drill to the Avon Park layer to begin with, McDermitt referred to the answer given to the Evan’s property question: They’re committed to giving full consideration to alternate water sources.
So far the power plant impacts have only been modeled by computer using existing well data, paid for by Florida Power & Light, but approved by the water district. The plant plans to draw about 40,000 gallons a day from surface water, which will not dry out plant life or have other impacts, according to the model.
But the draw from the upper Floridan Aquifer poses some risk to existing private wells close to the proposed plant site.
FPL will have to conduct pumping tests to confirm the model. The tests will determine how fast and how much water moves horizontally and vertically through the geological layers and if the confining layers protect one aquifer from another. The likelihood or existence of salt-water infiltration will be determined. FPL has two years after operations start to complete the pumping tests. Operations are slated to begin 2019.
At every juncture, if the tests reveal different results from the model, if the existing wells are affected, if already existing legal users are affected, FPL is required to fix the problem. Otherwise, their water use permit will be pulled.
Not all the water will be used up in the cooling and steam-making processes. Of the 9 million gallons used per day, 7 million will evaporate. But the remaining 2 million gallons, increasingly concentrated with particulates, nutrients and chlorides, will be injected into the “boulder zone,” several layers down from the upper Floridan Aquifer.