Located in Abu Dhabi in the United Arab Emirates, Masdar City is a city completely sustained by renewable energy. With a population of approximately 50,000, the city’s goal is to show the world it is possible for a city to be powered without the use of fossil fuels. To help achieve this, earlier this year Masdar City launched a solar thermal cooling installation, on which construction began in early 2008.

Concentrating on cooling

The system employs MicroCSP solar collectors, developed by Sopogy, a United States-based manufacturer of concentrated solar technology. The MicroCSP solar collectors concentrate the sun’s heat onto receiver tubes containing heat transfer fluid. This heat transfer fluid is the fuel for powering the solar air conditioning system. The heat transfer fluid then circulates through the solar array to reach temperatures of 133 °Celsius.

The MicroCSP Collector solar field, used to collect the sun’s heat, comprises five rows of 12 SopoNova parabolic collectors – also developed by Sopogy – covering an area of 569 m2. The SopoNova collectors have an efficiency factor of 58.97 per cent, the highest of any Solar Rating and Certification Corporation-rated MicroCSP collector.

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Solar cooling at Masdar City is produced through a 45 tonne, double-effect broad chiller. Within the chiller, hot transfer fluid from the MicroCSP collectors heats a solution of water (refrigerant) and lithium bromide (absorbent) in a vacuum under low pressure. The low pressure enables water to vaporize at a low temperature. This phase change from liquid to vapour produces a chilling effect, and fans then carry the cool vapour through the Masdar City cooling system.

Meanwhile, the water vapour is then turned back into liquid in the system’s condenser, and is recombined with the lithium bromide in the absorber to be reused.

Masdar shines for the environment

Generally, absorption chillers are run by boilers powered by diesel, bunker oil or natural gas. In the instance of Masdar City, however, the use of Sopogy MicroCSP solar collectors replaces these fossil fuels with clean, renewable energy.

The 45 tonne output of the MicroCSP solar cooling system at Masdar City will reduce carbon dioxide emissions by 1,830 tonnes over the lifetime of the project. For perspective, the system's impact is equivalent to:

  • Saving 4,290 barrels of oil annually
  • Removing 360 cars off the road
  • Saving 1,350 tonnes of coal annually.