Masdar turns to sun’s heat to cool buildings

Masdar has successfully activated a proprietary double-effect solar thermal cooling system – the first in the Gulf region and one of only a handful in the world – to test the viability of using the sun’s heat to cool buildings at Masdar City, the emerging low-carbon cleantech cluster being constructed on the outskirts of the UAE capital Abu Dhabi.

Designed and engineered by Masdar, the pilot plant is the only one in the world to combine two different concentrating solar thermal collector technologies in a single system.

“Green” air conditioning systems generally consist of conventional compression chillers powered by electricity from photovoltaic panels or concentrated solar power plants. While such conventional chillers and air conditioners use electricity to run a compressor, a double-effect absorption chiller such as the one being tested at Masdar City uses heat to activate a chemical process that provides chilled water for cooling.

If successful, the technology could become a major source of cooling across the 6km2 city. Solar cooling is ideal for medium-scale cooling loads, such as those of supermarkets and shopping malls and can also be implemented in a central cooling plant configuration (“district cooling”). It is especially well suited to address peak cooling demand as the solar thermal energy supply closely matches high daytime cooling demand.

“This project reflects the ongoing innovation taking place at Masdar City as we push the boundaries of sustainable cooling to deliver new solutions that not only compete with conventional systems in terms of quality but also excel in terms of what we can achieve via optimised and cost-effective implementation of state-of-the-art solar technologies,” according to Afshin Afshari, Head of Energy Management at Masdar City.

The collectors include a Sopogy parabolic trough collector with uniaxial tracking and a total mirror aperture area of 334m2. It heats thermal oil, whose heat is transferred to the system’s pressurised water circuit through a heat exchanger. A Mirroxx linear Fresnel collector with uniaxial tracking and a total mirror aperture area of 132m2 heats the pressurised water directly.

Schneider Electric provided the control system components for the pilot plant and EM Hidromontaza installed the integrated system. The Fraunhofer Institute of Solar Energy will analyse the monitored data and assess system performance.

”The two solar thermal collector systems have been in successful test operation already for more than three months,” explained Simon Bräuniger, project manager for Masdar’s pilot plants. “The collector’s thermal energy has been driving the Broad 50-refrigeration-ton double-effect absorption chiller that is cooling our office building since mid-September, marking the start of full operation for the pilot project.”

The system provides sustainable cooling to 1700m2 of office space using advanced air-conditioning and delivery equipment from Swegon, such as active chilled beams and an air handling unit that achieves 75% energy recovery.

The objective is to demonstrate that high-temperature solar thermal cooling is more cost effective and requires a smaller collector footprint compared to a conventional electric chiller plant powered by solar-generated electricity. The solar cooling pilot installation produces cooling equivalent to approximately 80 conventional split-type air conditioning systems, leading to annual emissions reductions of approximately 70,000 kg of CO2.