Molten Salt Technology Allows US Solar Plant to Generate Electricity at Night

The US has just recently brought online a solar power plant that can produce electricity for the grid, even during the night. The 280 megawatt Solana solar power plant located on a three-square-mile commercial-scale facility near to Gila Bend, Arizona, uses a molten salt thermal energy storage system to allow it to continue generating energy even when the sun is no longer shining.

A press release from the Arizona Public Service (APS), Arizona’s longest serving electric company, explained that “this technology enables Solana to produce electricity at full capacity for up to six hours after sunset, including the early evening hours when customer demand for power typically peaks in Arizona.”

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APS claims that the Solana solar power plant is the largest in the world to use parabolic mirrors to focus the sun’s rays onto a system of pipes containing a synthetic oil. The hot oil then boils water, and the steam drives two 140 megawatt turbines to produce electricity.

The Solana solar power plant in Arizona. (Arizona Experience)

Most concentrated solar power (CSP) plants work on a similar system, but unlike others, at night the turbines do not stop turning. During the day the heat reflected onto the tower is also used to heat molten salt, which holds its temperature for a long time. When the sun goes down the molten salt is used to heat the water and create the steam, and the electricity continues to be generated for up to an additional six hours.

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Abengoa Solar, the operator of the Solana power plant, states that the “ability to generate electricity when needed, or dispatchability, is one of the unique characteristics of concentrating solar power versus other types of renewables.”

APS has already agreed to purchase all electricity produced at the solar power plant, boosting the amount of electricity it gets from solar power by almost 50%, and giving them enough capacity to supply an extra 70,000 homes. APS say that they plan to have 750 megawatts capacity of solar power by the end of the year, enough to supply 185,000 households.

By. Joao Peixe of Oilprice.com