Final Tests For Torresol’s CSP Plant With Molten Salt Storage Complete  

The National reports that Torresol’s solar thermal power plant in Spain has completed testing - Spanish solar plant built by Masdar is well worth its salt. The plant includes 15 hours of storage, making it able to operate around the clock for much of the year.

A Spanish solar plant built by an Abu Dhabi company is set to power homes even during the night. Masdar, which is owned by Mubadala Development, and a Spanish joint venture partner have completed the final tests on a solar plant in Seville, in southern Spain. …

Thousands of mirrors at the plant concentrate the sun's energy on a single tower holding molten salt, which developers believe is so effective at retaining heat that it will be able to produce power 24 hours a day from March to October. "We're basically decoupling the solar [input] from the electricity generation," said Frank Wouters, the director of Masdar Power.

The tower is the first part of Masdar's €1 billion (Dh5.18bn) investment in Spanish power production. That includes two 50 megawatt solar parks being built by Torresol Energy, Masdar's 40-60 joint venture with the Spanish engineering company Sener.

In Spain, the company has three solar projects worth about $1 billion, Wouters said at a media briefing in Abu Dhabi today. A 20-megawatt plant will start producing power this month and two 50-megawatt facilities will start this year, he said. Masdar also has stakes in the 1-gigawatt London Array offshore windfarm and a 6-megawatt offshore wind project in the Seychelles.

Abu Dhabi, which holds almost all the oil reserves in the United Arab Emirates, is investing in solar and wind power all over the world to pioneer the use of renewable energy. The emirate is building Masdar City, a business and residential complex designed to minimize carbon emissions, and serves as headquarters for the International Renewable Energy Agency.

Masdar is a key component of Abu Dhabi’s aim to generate at least 7 percent of the power it uses from renewable sources by 2020. Growth in power demand to more than 20,000 megawatts by the end of the decade would require about 1,500 megawatts from projects such as wind and solar plants, according to data from Abu Dhabi’s utility.

The company’s domestic projects include the Shams 1 project, the largest concentrated solar plant in the Middle East, which is 45 percent complete and will be ready next year, according to a statement received by e-mail today. Masdar expects to award a construction contract for the 100-megawatt Noor 1 photovoltaic plant by the end of 2011 and may start building a 30-megawatt wind farm on Sir Bani Yas island.

Concentrated solar power (CSP) uses mirrors to concentrate sunlight and generate heat and is typically used to generate electricity via a conventional steam cycle.
Unlike photovoltaic farms or wind energy — which has grown to become Spain's third largest power source — CSP plants can cost-effectively store energy that cannot immediately be used. In Spain, which has a second demand peak in the evening, this is important. Most new CSP projects incorporate storage so they can keep generating electricity several hours after the sun has gone down, or even right through the night.

But, while CSP is more dispatchable than other renewable energy sources, it also currently costs more. So Spain is the focus for efforts to drive down costs, both through economies of scale and improvements in technologies.

'All the CSP technologies are expensive so a lot of research seeks to reduce component costs and optimise production and installation,' says Eduardo Zarza, head of R&D for solar concentrating systems at the Plataforma Solar de Almería (PSA), Spain's leading solar energy research centre, which researches all four types of CSP technologies. The most mature CSP technology is the parabolic trough design, which accounts for 93% of the 2500 MW of new CSP capacity that Spain has authorised up to 2013. While the other three technologies — solar tower, Fresnel collector and Stirling dish — all have commercial potential, the financial backers of Spain's CSP projects have opted to reduce their risks through parabolic trough's longer track record. In the US, parabolic-trough plants date back to the 1980s.

'With a tower system, for example, it is difficult to get project finance because no one knows how long the receiver will last,' says Frank Dinter, head of solar at RWE, the German utility, which is investing in several Spanish renewable projects.

To benefit from Spain's generous feed-in CSP tariff — currently 28 euro cents/kWh for 25 years — CSP plants cannot exceed 50 MW. This size limit is seen as less than optimal, given the current maturity of parabolic-trough technology, and limits potential benefits from economies of scale. Several costs in a CSP project are not proportional to its size. For example, a 200 MW turbine costs less than four times as much as a 50 MW turbine. Dinter estimates that a 200 MW plant would be about 25% cheaper per megawatt than a 50 MW plant. ...

The best places to locate CSP plants tend to be arid regions with little cloud, but such environments are often subject to water restrictions. A plant such as Andasol 3 consumes 500,000 m² of water a year, mostly to condense steam, but also to clean mirrors.Investors in Novatec Solar's PE2 plant insisted on air cooling to avoid such controversy, even though reduces the economic return.

'Air cooling costs much more and it reduces the output by 5%-6%,' says Selig. Opinions are nevertheless divided on this issue. RWE's Dinter says water cooling is essential to boost the thermodynamic efficiency of the steam cycle of parabolic-trough plants like Andasol 3 with a relatively low inlet temperature. 'With dry cooling, you cannot reduce the outlet temperature as much as with water,' he says.

Burgaleta of Torresol Energy says that even though the Gemasolar central tower plant works at higher temperatures, water access was not a problem, and so the designers opted for water cooling. But one of Torresol's central tower projects planned for the future will have air cooling instead, he adds.

As Spain is now discovering, concentrating solar power is far from being a single technology, but rather embraces a wide range of designs and key technologies, each with different operating characteristics, risk profiles and trade-offs. 'There is no clear winner,' clarifies Siemens' Mürau.
Even without any radical technological breakthroughs, improvements in technologies and greater economies of scale are expected to drive a 30% reduction in the cost of CSP-generated electricity in Spain by 2015. And by 2025, costs may fall as much as 50%, at which point CSP plants will finally be in a position to substitute conventional sources in Spain's energy mix.