La peculiaridad de esta central es que dispone de un acumulador de calor que permite que sus turbinas de vapor sigan funcionando cuando no hay luz solar.
El calor del Sol lo almacenan 28.500 toneladas de sal; esta sal puede acumular calor suficiente como para hacer funcionar las turbinas de vapor durante unas siete horas después de la puesta del Sol. El resultado es que esta central puede garantizar un suministro de energía constante, que no está condicionado por las inclemencias del tiempo.
La presencia del acumulador no solo no ha encarecido el sistema, sino que lo ha abaratado. Según sus constructores, la energía producida por esta central costará 271 euros el MWh, frente a los 303 euros el MWh de coste de las centrales termosolares convencionales.
Andasol 1, conectada a la red en noviembre de 2008, es la primera de un conjunto de tres centrales, con un coste de 260 millones de euros cada una y que producirán energía para unos 250.000 hogares. Las empresas que han acometido el proyecto son Flagsol, Solarmillennium y ACS.
Andalucía tiene actualmente en funcionamiento 81 MW termosolares para la generación de electricidad y cuenta además, con otros 7 proyectos en construcción en las provincias de Sevilla, Córdoba y Granada, que sumarán una potencia total de 317 MW. De ellos, 300 MW se prevé que estén finalizados entre los años 2009 y 2010, lo que permitirá a la región seguir a la cabeza de las comunidades autónomas en el desarrollo de esta tecnología solar.
Andasol está ubicada en la altiplanicie de Guadix en la provincia de Granada y ya está produciendo electricidad y conectada a la red eléctrica española.
El calor lo producen espejos en forma de cilindros parabólicos que recogen la luz del sol y la concentran en el eje focal. Una de las características más interesantes de Andasol 1 es que parte del calor se almacena en dos grandes cilindros llenos de sales. Ese calor, por la noche, o cuando el sol está nublado, se utiliza para producir vapor y electricidad.
Cuando los depósitos están llenos pueden seguir produciendo electricidad durante 7,5 horas. En los depósitos hay un 60% de nitrato sódico y un 40% de nitrato potásico. Cada depósito es un cilindro con 36 m de diámetro y 14 m de altura, lo que le da una capacidad de 28 500 tm.
Andasol II, que es una central gemela, se terminará a lo lardo de 2009. La superficie utilizada por cada una de ellas es de 510 000 m2; es decir, aproximadamente un cuadrado de 714 m de lado, capaces de producir electricidad para 100 000 personas.
En el mundo hay aproximadamente 6 500 000 000 personas, por lo tanto, para proporcionar energía a todas ellas (al mismo nivel que en Andalucía) necesitaríamos unas 65.000 centrales como Andasol 1. Dichas centrales necesitarían una superficie de 33.150 km2 que equivale a un cuadrado de 182 km de lado, menos que Extremadura (41.634 km2).
Incluso aunque la superficie ocupada, con todo tipo de servicios auxiliares y otras tecnologías (centrales de torre o solar fotovoltaica) fuera el doble, la siperfice no representa ningún proble, por la mera existencia de millones de km2 de desiertos en América del Norte y del Sur, África, Asia y Australia. El 90% de la población mundial vive cerca de los desiertos. Si se utiliza el Sahara y otros desiertos, tenemos una idea clara del papel que puede jugar la solar termoeléctrica en las próximas décadas, siempre que pueda reducir los costes a unos 80 o 90 euros por MWh, es decir, un tercio de los costes actuales.
Tanto en Andasol 1 como en Andasol 2 participa el grupo ACS/Cobra como socio de Solar Millennium AG al 75%. El grupo ACS/Cobra es el responsable de la construcción de las centrales y aprovecha las experiencias y prestaciones de Solar Millennium AG; la empresa Flagsol GmbH, una filial de tecnología de Solar Millennium AG, aporta la ingeniería para el campo solar así como la planificación, el dimensionamiento y la supervisión de la construcción y los equipos de control.
En las inmediaciones se construye una nueva planta, Andasol 3, cuyo tipo de construcción es en lo esencial idéntica a las de Andasol 1 y Andasol 2.
Solar Millennium ha vendido la empresa proyecto para la planta cilindro parabólica Andasol 3, Marquesado Solar, S.L., a Solanda GmbH.
MAN Ferrostaal AG, empresa de Essen (Alemania), posee el 61,5% de Solanda GmbH. La participación restante del 38,5% la tiene Solar Millennium.
Dicho movimiento se ha hecho en respuesta al cambio por parte de los legisladores españoles de las condiciones para conceder las tarifas de suministro legalmente garantizadas. Entre otros requisitos, se deben facilitar las pruebas de los permisos más importantes y de la adquisición de componentes clave. Además, se requiere la capacidad de financiar al menos el 50% de la inversión total del proyecto respectivo a la planta de energía con el fin de registrar previamente el proyecto y así asegurar las tarifas de suministro.
La entrada de MAN Ferrostaal en el proyecto asegura el desarrollo previsto de la construcción de Andasol 3, según Solar Millennium.
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Andasol solar power station
The Andasol solar power station is Europe’s first commercial parabolic trough solar thermal power plant, located near Guadix in the province of Granada, Spain. The Andasol 1 power plant went online in November 2008. In 2009, two more sections, Andasol 2 and 3, are under construction. The commissioning of Andasol 2 is scheduled for 2009, and Andasol 3 for February 2011. Andasol 1 cost around €300 million (US$380 million) to build.
The developers say Andasol’s electricity will cost €0.271 per kilowatt-hour (kW·h) to produce. In Spain, solar-thermal electricity receives a feed-in tariff of just under €0.27/kW·h for the next 25 years.
Andasol has a thermal storage system which absorbs part of the heat produced in the solar field during the day. This heat is then stored in a molten salt mixture of 60% sodium nitrate and 40% potassium nitrate. A turbine produces electricity using this heat during the evening, or when the sky is overcast.
This process almost doubles the number of operational hours at the solar thermal power plant per year. Thermal energy storage costs roughly US$50 per kilowatt-hour of capacity, according to Greg Glatzmaier of the U.S. National Renewable Energy Laboratory (NREL) — about 5% of Andasol’s total cost.
Andasol was developed by Solar Millennium AG, and it is the first parabolic trough power plant in Europe. Thanks to the high altitude (1,100 m) and the desert climate, the site has exceptionally high annual direct insolation of 2,200 kW·h/m²·yr. Each plant has a gross electricity output of 50 megawatts (MWe), producing around 180 gigawatt-hours (GW·h) per year (21 MW·yr per year). Each collector has a surface of 51 hectares (equal to 70 soccer fields); it occupies about 200 ha of land.
A full thermal reservoir can run the turbine for about 7.5 hours at full-load (375 MW·h), in case it rains or after sunset. The heat reservoirs each consist of two tanks measuring 14 m in height and 36 m in diameter and containing molten salt. Andasol 1 is able to supply environmentally-friendly solar electricity for up to 200,000 people.
The Andasol power plants are helping to meet summer peak electricity demand in the Spanish power grid primarily caused by air conditioning units. The electricity supplied from the Andasol plants is ideal for meeting the demand during the day, particularly early afternoon, when the power demand reaches its peak and solar radiation (as well as the power plant output) are also at their peak.
A feed-in tariff for solar thermal power pays 2.5 to 3 times the average power price for every MWh of energy generated for 25 years (though new rules will reduce the rate for future projects) but limits the capacity of qualifying facilities to 50 MW. Storage enables Andasol 1 to run its 50-MW turbine for more hours. Nava estimates that Andasol 1 will generate 178 000 MWh of renewable electricity per year, whereas the same field of solar collectors and turbine would turn out just 117 000 MWh sans storage—a difference worth more than 24 million euros per year (US $36 million) at today’s power prices.
The project is supported by the European Commission, DG TREN because of these reasons:
It is a first-of-its-kind, utility-scale demonstration of the solar thermal technology developments EUROTrough and Thermal Storage.
Subsequent to the development of an advanced collector structure within the EUROTrough project, this demonstration plant will be the first opportunity to proof and demonstrate the technical and economic viability of the new collector design.
Before the newly developed EUROTrough technologies can be utilized on a pure commercial base it is necessary to overcome the technical and economic risks of a large-scale installation.
The AndaSol project will be the first application of molten salt-based thermal storage technology with parabolic trough collectors. The heat exchange between the HTF fluid circulating in the solar field, the molten salt storage medium and the water/steam cycle will be optimized in this commercial scale design.
The procurement, installation and long time operation of new components within a working power plant scheme will enable the involved companies and research institutes to further improve components and production technologies. This will subsequently lower cost for following projects.
As a Solar Millennium partner, the ACS/Cobra Group has a 75% share in each of the Andasol 1 and Andasol 2 projects. The ACS/Cobra Group is responsible for the construction of the power plants, utilizing Solar Millennium’s experience and services. Flagsol GmbH, Solar Millennium’s technology subsidiary, provides engineering services for the solar field, i.e. the planning, design and construction monitoring and supplies the controls for the solar field. Construction of a third plant in the immediate vicinity, Andasol 3, has begun in August 2008 with the early works; it has virtually the same design as Andasol 1 and 2.
Solar Millennium Sells Andasol 3 to Solanda
Solar Millennium AG has sold the project company for the parabolic trough power plant Andasol 3, Marquesado Solar S.L., to Solanda GmbH. The acquisition price was kept confidential. MAN Ferrostaal AG holds a 61.5 percent stake in Solanda GmbH. The remaining share of 38.5 percent is held by Solar Millennium. The entry of MAN Ferrostaal into the project secures the scheduled construction progress of Andasol 3, even against the backdrop of the latest developments in Spanish legislation, Solar Millennium said.
With the Real Decreto 6/2009 passed on 7 May 2009, Spanish legislators have changed the conditions for granting legally guaranteed feed-in tariffs. Amongst other requirements, evidence of the most important permissions and the procurement of key components must be provided.
In addition, the ability to finance at least 50 percent of the investment total of the respective power plant project is required in order to pre-register the project and thus secure the feed-in tariffs. After registration with the authorities, which is expected to take place by the end of September for Andasol 3, the full feed-in tariffs will be guaranteed provided that the power plant is connected to the grid within the following 36 months.
List of solar thermal power stations
These include the 354 megawatt (MW) Solar Energy Generating Systems power plant in the USA, Nevada Solar One (USA, 64 MW), Andasol 1 (Spain, 50 MW), PS20 solar power tower (Spain, 20 MW), and the PS10 solar power tower (Spain, 11 MW).
The solar thermal power industry is growing rapidly with 1.2 GW under construction as of April 2009 and another 13.9 GW announced globally through 2014. Spain is the epicenter of solar thermal power development with 22 projects for 1,037 MW under construction, all of which are projected to come online by the end of 2010. In the United States, 5,600 MW of solar thermal power projects have been announced. In developing countries, three World Bank projects for integrated solar thermal/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco have been approved.
Under construction
* Martin Next Generation Solar Energy Center — Florida, USA, 75 MW steam input into a combined cycle, parabolic trough design.
* Andasol 2–3 — Granada, Spain, 50 MW each with heat storage, parabolic trough design.
* Alvarado/La Risca 1 solar power station — Badajoz, Spain, 50 MW , parabolic trough design.
* Solnova 1, 3 solar power station — Spain, 50 MW , parabolic trough design.
* Extresol 1 solar power station — Spain, 50 MW , parabolic trough design.
* Kuraymat Plant — Egypt, 40 MW steam input for a gas powered plant, parabolic trough design.
* Hassi R’mel integrated solar combined cycle power station — Algeria, 20 MW steam input for gas powered plant, parabolic trough design.
* Beni Mathar Plant — Morocco, 20 MW for hybrid power plant, technology unknown.
* Solar Tres Power Tower — Spain, 17 MW with heat storage, power tower design.
* Solar demonstration plant — 5 MW, Lancaster, California.
Announced-Spain
* Extresol 2–3 — Badajoz, Spain, 50 MW each with heat storage, parabolic trough design.
* Andasol 4–7 — Granada, Spain, 50 MW each with heat storage, parabolic trough design.
* Manchasol 1–2 — Ciudad Real, Spain, 50 MW each with heat storage, parabolic trough design.
* Solnova 2, 4–5 — Sevilla, Spain, 50 MW each with heat storage, parabolic trough design.
* Ecija 1–2 — Ecija, Spain, 50 MW each with heat storage, parabolic trough design.
* Helios 1–2 — Ciudad Real, Spain, 50 MW each with heat storage, parabolic trough design.
* Termesol 50 — Seville, Spain, 50 MW with heat storage, parabolic trough design.
* Arcosol 50 — Cadiz, Spain, 50 MW with heat storage, parabolic trough design.
* Ibersol Badajoz — Fuente de Cantos, Spain, 50 MW, parabolic trough design.
* Ibersol Valdecaballeros 1–2 — Valdecaballeros, Spain, 50 MW, parabolic trough design.
* Ibersol Sevilla — Aznalcollar, Spain, 50 MW, parabolic trough design.
* Ibersol Almería — Tabernas, Spain, 50 MW, parabolic trough design.
* Ibersol Albacete — Almansa, Spain, 50 MW, parabolic trough design.
* Ibersol Murcia — Lorca, Spain, 50 MW, parabolic trough design.
* Ibersol Zamora — Cubillos, Spain, 50 MW, parabolic trough design.
* Enerstar Villena Power Plant — Villena, Spain, 50 MW, parabolic trough design.
* Aste 1A, 1B, 3, 4 — Alcázar de San Juan (Ciudad Real), Spain, 50 MW each, parabolic trough design.
* Astexol 1–2 — Extremadura, Spain, 50 MW each, parabolic trough design.
* Palma del Rio 1–2 — Cordoba, Spain, 50 MW each, parabolic trough design.
* AZ 20 — Sevilla, Spain, 20 MW , power tower design.
* Almaden Plant — Albacete, Spain, 20 MW, power tower design.
* Gotasol — Gotarrendura, Spain, 10 MW, linear fresnel design.
* Aznalcollar TH — Sevilla, Spain, 80 kW, dish sterling design.
Announced-Other
* Negev Desert, Israel, 250 MW, design will be known after tender.
* Upington, South Africa, 100 MW, power tower design.
* Shams, Abu Dhabi Madinat Zayad, 100 MW, parabolic trough design.
* Yazd Plant — Iran, 67 MW steam input for hybrid gas plant, technology unknown.
* Archimede — near Siracusa, Sicily, Italy, 28.1 MW with heat storage, parabolic trough design.
* Solenha — Aspres sur Buëch, France, 12 MW with heat storage, parabolic trough design.
* Cloncurry solar power station — Australia, 10 MW with heat storage, power tower design.
* Nagpur, India, 10 MW, design unknown.
Out of commission
* Solar One (converted into Solar Two) — USA California, 10 MW, power tower design.
* Themis (under rehabilitation) — France, 2 MW, power tower design.
* SES-5 — USSR, 5MW, power tower design, water / Steam, service period 1985-1989.
www.solarmillennium.de/upload/Animationen/andasol_blue_spa.swf
www.sener-power-process.com/ENERGIA/area-energia-sol.html
www.solarmillennium.de/upload/pdf/Andasol1-3spanisch.pdf
www.nrel.gov/csp/troughnet/pdfs/2007/martin_andasol_pictures_storage.pdf
www.solarmillennium.de/upload/Download/Technologie/eng/Andasol1-3engl.pdf
