According to the Frost & Sullivan Annual Renewable Energy Outlook and World Energy Investment Outlook for 2014, “The global demand for renewable energy generation is expected to grow by 45% by 2020.” There are new solar plants popping up more frequently today, and in locations all over the world. They are being built in various sizes and using an array of different methods to power both residential homes and commercial properties.
Photovoltaic Solar vs. Concentrated Solar
Photovoltaic solar technology requires use of the sun’s rays in conjunction with panels, which in turn converts sunlight into electricity. Unfortunately, the solar panels are only effective during daylight hours.
While photovoltaic solar power plants are most common, concentrated solar plants have recently become more popular, as they allow access to on-demand energy to produce electricity, both day and night. Using mirrors to concentrate the sun’s energy to create electricity, concentrated solar power plants provide thermal energy that can be stored for longer periods of time.
Crescent Dunes Project
In the U.S. alone, there are upwards of 1800 megawatts (MW) of concentrated solar plants currently operating. The Crescent Dunes project, located in Tonopah, Nevada, is the world’s first utlity-scale concentrated solar plant. The 110-megawatt solar energy plant is strong enough to power 75,000 homes throughout the state of Nevada.
“Having to build a second power plant to back up a solar array is not an ideal solution to say the least. Thermal solar resolves that issue all while letting facilities like SolarReserve’s store 1,100 megawatt-hours of energy,” stated OilPrice.com.
How Does Concentrated Solar Work?
Concentrated solar plants employ a complex process involving movable mirrors (also called heliostats), to reflect the sun’s energy to heat up salt. The result is molten salt, which is then used to store energy that can later be used to produce electricity.
The Crescent Dunes concentrated solar plant uses over 10,000 heliostats to reflect solar energy to a tower that sits 640 feet high. The tower consists of salt that is heated to 1,050 degrees Fahrenheit. Whenever electricity is needed, the molten salt can be transferred through a heat exchanger, creating high temperature steam to power traditional steam turbines.
Why Molten Salt
Salt is used specifically because of its ability to retain extremely high levels of heat. The salt acts like a “thermal battery”, which can be used at a later time, regardless of whether the sun is shining or not. Using molten salt for both heat transfer and thermal energy storage keeps the number of storage tanks to a minimum, and lowers the volume of salt required as well.
The process does not create any carbon emissions or hazardous waste, and there are no fuel costs associated with creating concentrating solar energy. The result is the creation of a large amount of clean and quiet energy, that can be stored for later use upon demand, any time of day or night.
In addition to the Crescent Dunes project, two similar additional solar plants in South Africa and Chile are in the works, promising to bring disruptive and innovative technology to each country that will change the way they create and store electricity for years to come.
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