Gemasolar, a 19.9 MW concentrated solar power (CSP) plant in southern Spain, has achieved 24 hours of uninterrupted electricity supply to the grid through its molten salt energy storage technology.

The plant’s thermal storage enables it to continue generating for 15 hours without solar radiation, according to its owner Torresol Energy, a joint venture between Abu Dhabi’s Masdar and Sener, a Spanish engineering and construction company.

Several days of excellent solar radiation at the end of June enabled Gemasolar to achieve its first 24 hours of interrupted electricity production, said Diego Ramírez, director of production at Torresol Energy.

But the plant, which was commissioned in May, is expected eventually to achieve 24 hours of uninterrupted supply on most summer days.

Gemasolar is described by Torresol Energy as the first commercial-scale plant to apply molten salt heat storage in a configuration with a central tower and an array of heliostats.

Molten salts – 60 per cent potassium nitrate and 40 per cent sodium nitrate – operate directly as a transfer fluid reaching temperatures of more than 500°C and store heat with a loss of only 1 per cent per day, said the firm.

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