By Tildy Bayar, Associate Editor, Decentralized Energy
District cooling is a multi-billion dollar industry in the Middle East, with demand climbing and no sign of a slowdown in sight. District cooling systems deliver chilled water from a central plant through an underground pipe network to multiple buildings. The water circulates through refrigeration coils, or enters the air conditioning system through absorption chillers. The energy needed to drive the chillers can come from multiple sources including waste heat from power plants or industrial processes; steam turbines, or electric chillers. The cooling water can be fresh water, seawater or treated sewage effluent (TSE), a relatively new source of cooling water within the industry. According to the United Nations Environment Programme (UNEP), district cooling can be more than twice as efficient as traditional decentralised air-conditioning methods, and can reduce electricity use significantly during peak demand periods through decreasing power consumption and use of thermal storage. District cooling systems can also be less costly than using electricity to run compressors for cooling. While district cooling systems can replace any traditional cooling method, their biggest competitors are air-cooled reciprocating chiller systems designed for buildings with high power demand. According to a history of the district cooling sector compiled by George Berbari, CEO of UAE-based DC Pro Engineering, the first centrifugal water-cooled chiller was developed by one Dr Willis Carrier in 1922. The technology subsequently became the most widespread in the sector and led to the world's first district cooling scheme, installed at the Denver, Colorado Automatic Refrigerator Company in the US in 1889. During the 1930s, New York City's Rockfeller Centre and Washington DC's US capital buildings featured district cooling systems. Today district cooling has become a multi-billion dollar industry, with global demand for cooling continuing to rise. According to the International Energy Agency (IEA), power consumption for space cooling grew by 60% worldwide between 2000 and 2010.
Dubai's d3 design district. Credit: IDEA/d3
In the Middle East, centralised chilled water plants have been in use since the 1960s. According to Berbari's history, the region's first commercial district cooling scheme was developed by the UAE's National Central Cooling Company (Tabreed) in conjunction with the UAE Army at Zayed Military City in Abu Dhabi. The scheme's natural gas-driven centrifugal chillers, the region's first, were built by Caterpillar, with research funded by the US Gas Research Institute. The Middle East as a whole installed 75.5 million square feet (7 million m2) of district cooling capacity in 2014, according to the latest figures from the International District Energy Association (IDEA). And, according to market forecasts, the region's district cooling market is projected to grow by more than 16% over the coming five years. Ahmad Bin Shafar, CEO of the Emirates Central Cooling Systems Corporation (Empower), has described the regional market as 'going from strength to strength' Dubai According to UNEP, air conditioner use accounts for 70% of Dubai's electricity demand. In order to reduce its energy use, the city has developed the world's largest district cooling network, providing 1 million RT per year and attracting over $150 million in investment between 2009 and 2014. Through this network, Dubai is on track to achieve its goal of meeting 40% of its cooling demand through district cooling by 2030. Meeting this target is expected to reduce the city's power consumption for air conditioning by 50%.
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