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By Alma Rosa López Martínez
Resumen
When anyone hears about renewable energies, the
first thing he thinks is in its benefits, they are inexhaustible, they are
clean and we can use them in the same place where they occur. But what happens when the wind stops
blowing? Or when the sun stops shining?
Here the idea of Thermal Storage was born.
Spain is the first country in the world to use
the renewable energy with a Thermal Storage System by inorganic salts. The
plant of Andasol-1 was opened last July in Aldeire, Granada. The plant can
operate up to seven hours without sun. Fuente de Andalucia, Seville has begun
to build the Gemasolar plant, this plant can operate up to fifteen hours
without sun.
The plant operation is simple and efficient, in
the first case of the Andasol-1 plant, the inorganic salts like Sodium Nitrate
and Potassium nitrate are stored in liquid in a cold thank at 293 degree
Celsius, when the sun is shining the salts are pumped to heat exchanger where
they absorb heat and reach the 393
degree Celsius. Then the salts are transferred to a hot tank. The same happens
when the sun stops shining, but now in a reverse way, the hot thank is
transferred to the cold tank, and the hot salts transfer energy to the fluid of
synthetic oil and the steam is generated.
Fig 1: Tanques acumuladores de planta Andasol 1
In the second case of the Gemasolar plant, the
plant operation is very similar than Andasol-1 plant. The sunlight shines on
the heliostats reflecting it to the receiver, in the cold thank the salts are
pumped to the top of the tower. At the
top of the tower the salts begin to heat, then the salts down into the hot tank
where they are stored at 500 degree Celsius. Then the salts pass through the
heat exchanger pipes, when the salts lose heat the steam is generated and the
turbine operated of the electrical generator is activated.
Fig
1. Esquema del flujo del proceso de una típica planta
cilindro-parabólica con
dos tanques de almacenamiento de térmico
With the prolongation of plant operation in the absence of radiation,
Spain has taken a big step into the world of renewable energy by continuing its
technological and commercial growth.
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