The 17-megawatt (MW) Gemasolar project is being built near Seville by Torresol Energy, a joint venture owned 60% by Spanish engineering firm Sener and 40% by Masdar, Abu Dhabi’s renewables development vehicle.

Gemasolar, which started construction in November 2008, will be the world's first commercial-scale CSP plant to utilise a molten salt heat-storage system. The project will incorporate a central tower and 2,600 heliostats, or sun-tracking mirrors.

Torresol claims that by using molten salt to generate steam, as opposed to the synthetic oil used by existing CSP projects, it will be able to produce electricity for up to 15 hours a day. In comparison, oil-based CSP installations can only store energy for around an hour after the sun has set.

“We are confident that central tower technology using molten salt offers the greatest development potential for the future,” says Torresol chairman Enrique Sendagorta.

Earlier this year Siemens took a 28% stake in Italian firm Achimede Solar, which is also investigating the potential of molten salt storage systems. Siemens says one advantage of the technology is, unlike the synthetic oil used in most parabolic-trough CSP plants, salts do not need to be replaced.

Gemasolar is expected to produce 100 gigawatt hours of electricity each year, which will be exported via high-voltage lines to the grid in Villanueva del Rey, in the Spanish provice of Andalusia.

Torresol is also developing two 50MW parabolic trough plants in the province of Cadiz, and intends to build “at least two” CSP plants a year over the medium term.

The EIB, the EU’s long-term investment arm, has ploughed billions into loans for renewable-energy and other low-carbon projects in recent months, including £700m ($1.2bn) for UK onshore wind, €300m for Belgian offshore wind farm Belwind, and another €300m for a high-voltage electricity link between Ireland and Wales.