Wednesday, November 21, 2012

Solar power plant with mirrors – Florida example

The largest solar power plant in the United States is located in California's Mojave Desert and is owned by Florida Power & Light Co (FPL). Florida Power & Light Co has not stopped on just one project and has also constructed large solar power plant at the Martin Next Generation Solar Energy Center in Indiantown, the one that is now the second largest solar power plant in the world, with the capacity to generate electricity for around 11,000 homes. The precise location of this solar power plant is in western Martin County, Florida, just north of Indiantown.

What is special about this solar power plant? Solar facilities that use this principle have mirrors to generate heat, heat then produces steam, and afterwards steam spins turbines to generate electricity. Since Florida has pretty regular afternoon rain clouds throughout much of the year, there have been doubts about the effectiveness of this principle, and this is the reason why all other solar power plants built in Florida convert sunlight directly into electricity using photovoltaic panels, which produce a charge even on cloudy days (though a reduced one).

The main difference with this solar power plant is the fact that this plant was built on a campus near Lake Okeechobee, an area already equipped with 13 generators powered by oil and natural gas. Constructors have therefore used a different approach as they have combined steam from the solar plant with the steam produced with the heat exhaust from four natural-gas plants to spin an existing generator.

This combination is what gives this project feasibility because the utility won't have to spend millions of dollars building a generator for the solar plant. However, cloudy days still pose a certain issue because during partly cloudy days some of the plant's mirrors reflect full sunlight while others are shaded. Plant engineers definitely want to avoid alternating pulses of cooler and hotter steam arriving at an electrical generator that runs most efficiently, and they are already thinking about possible solutions for this issue.

So, Martin Next Generation Solar Energy Center is a hybrid, 75MW, solar energy plant. The solar plant is a component of the 3,705 MW Martin County Power Plant, which is currently the single largest fossil fuel-burning power plant in the United States. This is the first hybrid solar facility in the world to connect to an existing combined-cycle power plant. As of 2012, no additional concentrated solar plants are planned for Florida.

This project was connected with large costs, approximately $476 million, and it has been calculated that it adds about 16 cents a month to the average FPL residential customer's bill. Martin Next Generation Solar Energy Center should have a respectable lifespan of 30+ years.

This large solar power plant has enough mirrors to cover 80 football fields and these mirrors are mounted to focus sunlight onto surfaces that add up to slightly less than the area of a single football field. The mirrors have been installed in aluminum frames to create long, linear dishes. The more than 6,800 frames each containing 28 mirrors have been arranged in parallel rows that are linked together for a total length of about 50 miles.

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