Gemasolar has completed the construction of the world’s first solar power plant capable of generating electricity all day and night. As significant as the “all night” feature sounds, keep in mind that the fact that solar power plants do not normally generate electricity at night is not actually their biggest reliability obstacle — the electricity generation interruption from clouds is more problematic (see more on that below). Luckily, this power plant design tackles both issues.
This plant is able to produce electricity all day and night due to the fact that it has 15 hours of energy storage to back it up, when cloudy and at night too.
The fact that weather varies unpredictably during the day, causing power production to fluctuate is much more important than the lack of sunlight during the night, because power plant operators know exactly when night time starts, so any other power plant can be scheduled to start for night time operation.
Conventional coal, nuclear and steam natural gas power plants cannot be started quickly enough to compensate for cloudy weather. Therefore, solar power plants need to be backed up by peaking generators or energy storage.
This power plant is sometimes described as one which stores energy in a salt “battery” — it is not actually a battery, though. This type of power plant concentrates intensely hot sunlight onto what is called a collector, which then eventually transfers heat to molten salt where it is stored for later use.
Heat from the molten salt is used to help boil water when it is cloudy, and exclusively at night due to the absence of sunlight. Simply put: this is the storage of heat to boil water later if there is not enough solar energy to boil the water vigorously enough at that time.
This is called thermal energy storage. The salt being used is actually 60% potassium nitrate and 40% sodium nitrate and loses 1% of the heat being stored per day.
This is a 19.9 MW plant that is expected to produce 110,000 MWh or 110 GWh per year. The world’s first “baseload” solar power plant has been constructed in the Spanish province of Andalucia, Torresol.
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