Variable geometry solar power plant research

The Advanced Technology Centre for Renewable Energies (CTAER) has presented its ‘Variable Geometry Central Receiver Test and Research Facility’ at the SolarPACES 2012 conference.

Dr Valeriano Ruiz, President of CTAER, and Dr Manuel Silva have presented this new facility, the first of its kind in the world, which aims to assess the performance of central receiver systems under this new concept. Preliminary estimates point to 17% more efficiency than current plants.

The key points for this new facility is the use of ‘heliomobiles’, instead of heliostats. CTAER has given them this name due to their ability to move around the tower over rails. The receiver platform atop the tower is also mobile - it’s a rotating platform which turns on its axis.

Dr Ruiz describes the new research facility:

“A facility that intends to transform solar radiation into some other type of energy needs to analyse its source, which is none other than the sun. From the Earth’s perspective, the sun is in constant movement, a fact that we should not forget. This is the reason why I have designed a central receiver test facility, currently in its last phase of construction, which contains a field of mobile heliostats and a receiver mounted on a rotating platform. We have named this concept ‘variable geometry’.

“In this new concept of heliostats field, the heliostats, during the morning, are positioned on the west side of the field; at midday their position moves toward the north of the tower, and in the afternoon they are positioned on the east side. Throughout the whole day, they adopt different positions in order to redirect the direct solar radiation and to achieve the least geometric loss possible; that is, keeping the cosine of the angle of incidence (the angle between the solar ray and the normal to the reflecting surface of the heliomobile) as close to 1 as possible at each moment.”

The facility is located in Tabernas, being the first of a new set of research facilities for CTAER located next to the PSA-CIEMAT (Almeria Solar Platform). It’s in its last phase of construction and is expected to be operational by early 2013.

According to simulations carried out with the NSPOC program, a field of heliomobiles could achieve improvements in the cosine factor, enabling a significant increase of the efficiency of a present plant. The results show that during the sunlight hours of a day, the variable geometry plant increases its average efficiency by around 17% per year. During the sunniest months, improved efficiencies of up to 30% can be achieved.

The variable geometry solar facility is a project designed and developed by CTAER, a private foundation based in Andalucía (Spain) and constituted by a board with public and private participation. The project’s budget during its first phase is €5 million, and it is jointly financed by the Department of Economy, Innovation, Science and Employment of the Andalucía Regional Government (Junta de Andalucía), through an agreement with the Ministry of Economy and Competitiveness of the Spanish Central Government and the European Regional Development Fund (ERDF).

This facility is part of CTAER’s more comprehensive plan for developing research infrastructures aimed at offering solutions for improvements in the performance of solar thermoelectric plants of different technologies. The next facility already awarded is a test bench for parabolic trough, which will begin construction in the near future, followed by test benches for the Stirling dish and Fresnel technologies.

Source: GlobalSpec