Combined cooling, heating and power (CCHP), or tri-generation, and decentralised power generation began to make inroads into the GCC region in the 1970s.
The road traversed and the signposts ahead
In the UAE, gas engine-driven centrifugal compressors debuted in 1999 (4,000 tonnes of refrigeration (TR) in Zayed Military City) and was followed by several gas engine generators synchronised with grid power (50,000 TR in Zayed Military City between 2000 and 2007; 20,000 TR in Al Dhafra Air Base in 2004 and 15,000 TR in ICAD in 2003). After these projects took shape, due to a shortage in the supply of natural gas, and the lack of a well-established distribution system, the District Cooling industry shifted to electric-powered centrifugal chillers, with installation reaching close to 2.5 million TR.
However, the momentum in the UAE slowed down for want of a more rigorous push, which created an opportunity for pioneering efforts from other entities, which saved 40% primary energy for decentralised power generation, as compared to electric grid-powered District Cooling.
The existing natural gas-powered installation is now being upgraded and maintained but without any major upgrade, such as adding exhaust and jacket heat recovery.
CCHP still holds promise in Saudi Arabia, as diesel is available at competitive rates
The only addition in the UAE has been a natural gas engine operating with methane gas in Abu Dhabi, established around 2012, and another in Dubai around 2013, where steam generated from the gas turbine exhaust heat recovery boiler is used to power a 200 TR double-effect absorption chiller.
Will CCHP pickup in the UAE again? The price of natural gas and its availability are key drivers to sustain CCHP. The price is currently quite competitive in Abu Dhabi, at AED 8/million BTU, while in Dubai and the Northern Emirates, it varies between AED 4 and 30/million BTU. The availability of natural gas is limited to a few locations in the UAE, with only one distribution network in Sharjah, and with a planned distribution network in Abu Dhabi.
Given the situation of natural gas, it is difficult to see a comeback of CCHP in the UAE. However, that may change with bio fuels, biomass and change of policy towards the prioritisation of natural gas for CCHP with minimum efficiency of 80%.
In Saudi Arabia, one of the first installations using gas turbine exhaust heat recovery system to generate steam and power double-effect absorption chiller parallel with 6×5,000 TR electric centrifugal chillers was in King Saud University in Riyadh; the project was commissioned in 1978. It was followed by a decentralised power generation of 14 MW using diesel, dedicated for a 13,000 TR District Cooling project for Al Rashid Mall.
Al Bustan Residential Complex, which comprises more than 800 villas and amenities, took CCHP to a different level, where the six engines of 1.65 MW each were used with jacket and exhaust heat recovery to power a single-effect absorption chiller of 660 TR capacity and double-effect absorption chillers (2 x 1,000 TR capacity) in series with 5 x 1,000 TR electric centrifugal chillers in series with stratified chilled water thermal storage. The overall generating efficiency exceeded 75%, and resulted in a reduction of 60% of primary energy used, and emissions compared to electric District Cooling.
Distributed generation is extensively used in the Kingdom, as remote villages are powered by standalone remote diesel generators. National Tri-Generation and Al Aman have several operating CCHP plants.
CCHP still holds promise in Saudi Arabia, as diesel is available at competitive rates of 45 Ha/litre, which can comfortably compete with grid power of 30 Ha/ kWh. Furthermore, there are plans to distribute natural gas in a few locations in the country, which will further strengthen the future use of CCHP.
Oman, Qatar, Kuwait and Bahrain:
Oman distributes natural gas to a few locations, and Innovation Park, adjacent to Sultan Qaboos University, is planned for ultra-efficient tri-generation with generating efficiency exceeding 87%. As it is synchronised with 1 MW PV solar carports, it will result in 75% reduction in primary energy and emissions.
Oman is planning to import large quantities of natural gas from Iran, which will enhance its availability, and encourage CCHP in the long term.
Qatar, the world’s largest exporter of LNG, does not have natural gas networks, except in the industrial city. The prospect of CCHP in Qatar is directly linked to when the government intends to establish a natural gas distribution network.
Kuwait and Bahrain still need to traverse some distance towards achieving CCHP generation, but sporadic opportunities exist, and that might change things with master planning.
Why not CCHP?
That said, the falling price of diesel fuel is opening new doors for CCHP in the GCC region and elsewhere in the world, particularly on remote islands and far-flung areas. When we planned for District Cooling, 20 years ago, it was because it had the potential to reduce 40% electricity and emission compared to traditional air conditioning. And that created a six million TR industry in the GCC region, with more than USD 15 billion in investment. Tri-generation can reduce primary energy usage by 60%. If it is synchronised with competitive solar PV, it will reduce primary energy usage by 75%. Don’t you think that alone will lead to a bright future, particularly in the wake of COP 21 and the reduction or elimination of utility and fuel subsidies in most GCC countries?
George Berbari is the CEO of DC PRO Engineering. He can be contacted at firstname.lastname@example.org.
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