Solar power station works at night

2012-03-18 13:46

Madrid - A unique thermosolar power station in southern Spain can shrug off cloudy days: energy stored when the sun shines lets it produce electricity even during the night.

The Gemasolar station, up and running since last May, stands out in the plains of Andalusia.

From the road between Seville and Cordoba, one can see its central tower lit up like a beacon by 2 600 solar mirrors, each 120 square metres, that surround it in an immense 195-hectare circle.

"It is the first station in the world that works 24 hours a day, a solar power station that works day and night!" said Santago Arias, technical director of Torresol Energy, which runs the station.

The mechanism is "very easy to explain," he said: the panels reflect the sun's rays on to the tower, transmitting energy at an intensity 1 000 times higher than that of the sun's rays reaching the earth.

Produce steam

Energy is stored in a vat filled with molten salts at a temperature of more than 500 degrees C. Those salts are used to produce steam to turn the turbines and produce electricity.

It is the station's capacity to store energy that makes Gemasolar so different because it allows the plant to transmit power during the night, relying on energy it has accumulated during the day.

"I use that energy as I see fit, and not as the sun dictates," Arias explained.

As a result, the plant produces 60% more energy than a station without storage capacity because it can work 6 400 hours a year compared to 1 200-2 000 hours for other solar power stations, he said.

"The amount of energy we produce a year is equal to the consumption of 30 000 Spanish households," Arias said, an annual saving of 30 000 tonnes of CO2.

Generous state aid

Helped by generous state aid, renewable energies have enjoyed a boom in Spain, the world number two in solar energy and the biggest wind power producer in Europe, ahead of Germany.

For the Gemasolar solar product, foreign investors helped too: Torresol Energy is a joint venture between the Spanish engineering group Sener, which holds 60% , and Abu Dhabi-financed renewable energy firm Masdar.

"This type of station is expensive, not because of the raw material we use, which is free solar energy, but because of the enormous investment these plants require," Arias said.

The investment cost exceeds 200 million euros ($260 million).

But "the day when the business has repaid that money to the banks (in 18 years, he estimates), this station will become a 1 000-euro note printing machine!," he said, recalling that oil prices have soared from $28 a barrel in 2003 to nearly $130.

For now, the economic crisis has nevertheless cast a shadow over this kind of project: Spain is battling to slash its deficit as it slides into recession and has suspended aid to new renewable energy projects.

Andalusia, hard hit by the economic crisis with the country's highest unemployment rate at 31.23%, holds regional elections on March 25.

"We have three projects ready but stalled" because of the aid suspension, Arias said, admitting that in a difficult global economy the group has not managed to sell the Gemasolar techology abroad despite huge interest outside Spain.

  • TSR01 - 2012-03-18 23:31

    ""This type of station is expensive, not because of the raw material we use, which is free solar energy, but because of the enormous investment these plants require," Arias said." So they only use solar energy to construct the entire structure? Its a construct of light? How amazing, and hippy-trippy, from the sound of it. So, these "massive investments required" don't cover the costs of design, construction, materials used, and finalization of the project, in a more agreeable sum, purely because..... money makes the world go around? Taking anywhere between 22%~48% of investments as service charge and total assimilated value is unreasonable and unprofessional. If running an energy development research firm gets my sponsors who would be willing to drop $40m~$80m (and that's being conservative) as a business model cover payment, the development project could afford salaries of $50k per month, per employee, for the limited duration of development and installation. Don't know if I'm barking up the wrong tree here, but not every employee deserves that much, and not every person who gets paid that much, needs it. Oh well, if we need motivation for "green energy", I suppose there it is.

      piet.strydom - 2012-03-31 19:03


      John - 2012-03-31 22:41

      Piet. Dit werk so. Die donnerse hernieuwbares werk nie soos die donnerse groeneres seg nie. Het jy dit?

  • John - 2012-03-31 18:54

    TRS01 they are fooling with us. This is a picture of the Gemasolar plant: This is the decription the company concerned gives Note the nominal capacity, 19.9MW. I see the 185ha has been increased to 195. Is this the square area needed to include the circles around the tower? If so we are talking about a square 1.4 x 1.4 km. To put this in perspective, SA plans building 9600MW of nuclear power. If we built Gemasolar's instead, we would need 9600/19.9 = 483 Gemasolars. Built in a straight line, that would be a path 1.4km wide and 1.4*483 = 676.2km long. To put that in perspective, the straight-line distance between Cape Town and Port Elizabeth is 661 km. So, to me, there's a choice: Do we want nuclear or do we want to build paths a kilometer and a half wide and longer than the distance between Cape Town and Port Elizabeth? The cost? Well we are told $260 million in the article, so (multiplying by 8 to get approximate Rand, R2080 per Gemasolar, giving a total of 483x2080, just over a trillion Rand. There is a debate at the moment: How much would 9600MW of nuclear cost? Experts say: In the region of R350 billion. Pessimistic experts double that and doom-sayers double that again, taking us to 1.4 trillion. So before becoming pessimistic or prophesying doom, we are already at a trillion! So, TRS01, are we being fooled?!

      conrad.buitendag - 2012-11-06 14:55

      The reason why coal fired power stations are built is pure economics. Coal currently is around R18 per Watt, Nuclear between R35 and R60, and this type of solar is about R110 per Watt. Also, the area required for a solar plant with an equal output to a nuclear or coal station makes it unpractical. Where do you get 130 000 hectares of undivided open land to build such a solar station?

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