IMPLEMENTATION OF GAS DISTRICT COOLING AND COGENERATION SYSTEMS IN MALAYSIA

MISE EN OEUVRE DE SYSTMES DE GAS DISTRICT COOLING ET DE

COGNRATION EN MALAISIE

Seth Haron Gas District Cooling (M) Sdn Bhd, Malaysia

ABSTRACT

With its energy demand in the early 1990s growing at a high rate due to the countrys strong economic growth, Malaysia studied various options to improve the efficiency of its energy use. Since its natural gas reserves are almost four times that of its crude oil reserves, efforts were therefore centered on seeking ways to boost the use of natural gas to mitigate the growing domestic energy need. PETRONAS, the national oil company, subsequently studied and chose the District Cooling System using natural gas as the primary source of fuel. The Kuala Lumpur City Center development, which houses the PETRONAS Twin Towers, was subsequently chosen as the first project to use the Gas District Cooling (GDC) System. To acquire the technology and implement this project, PETRONAS created a new subsidiary, Gas District Cooling (Malaysia) Sendirian Berhad (GDC(M)). In the process of improving the plants efficiency, GDC(M) discovered that the GDC systems efficiency and project economics would be significantly enhanced if its is coupled to a Cogeneration system. Having proven the success of the GDC/Cogeneration system, GDC(M) embarked on a campaign to aggressively promote and seek new opportunities to implement the system, both in Malaysia and abroad. Apart from enhancing efficiency of energy use, and providing better project economics, the GDC/Cogeneration system also is environment friendly. Today, the GDC/Cogeneration systems is the system of choice for several important developments in Malaysia, which also includes the countrys prestigious projects such as the Kuala Lumpur International Airport and the New Federal Government Administrative Center in Putrajaya.

RESUME Au dbut des annes 90, face laugmentation rapide de la demande nergtique lie la forte croissance du pays, la Malaisie a d envisager diffrentes options pour amliorer son rendement nergtique. Les rserves de gaz naturel du pays tant prs de quatre fois suprieures celles de ptrole brut, les efforts se sont concentrs sur les moyens de stimuler la consommation de gaz naturel afin de rduire la demande nergtique nationale croissante. PETRONAS, compagnie ptrolire nationale, a opt pour le systme de refroidissement Gas District Cooling (GDC), qui utilise le gaz naturel comme source primaire de combustible. Lurbanisation du centre-ville de Kuala Lumpur, qui abrite les tours PETRONAS, a t choisie comme projet initial dutilisation du systme GDC. Afin dacqurir la technologie et de mettre en oeuvre ce projet, PETRONAS a cr une nouvelle filiale, la Gas District Cooling (Malaysia) Sendirian Berhad (GDC(M)). En cherchant amliorer le rendement de lusine, la GDC(M) a constat que lefficacit du systme GDC et la rentabilit du projet seraient amliores de faon significative par ladjonction dun systme de cognration. Le systme GDC/Cognration ayant prouv son efficacit, la GDC(M) sest lanc dans une campagne de promotion dynamique et de recherche de nouvelles possibilits damliorer ce systme, que ce soit en Malaisie ou ltranger. Outre une augmentation du rendement nergtique et de la rentabilit, le systme GDC/Cognration offre galement une solution non polluante. Aujourdhui, en Malaisie, le systme GDC/Cognration constitue LA solution des programmes importants, y compris des projets de grande envergure comme laroport international de Kuala Lumpur ou le nouveau centre administratif du Gouvernement fdral Putrajaya.

1. INTRODUCTION

Between 1988 and 1997 the Malaysian economy registered a strong rate of growth of over 8 percent per annum. The robust expansion of the economy resulted in the country's energy demand to increase at a high rate of almost 10 percent a year during that period. Malaysia however was fortunate because it was blessed with abundant hydrocarbon reserves, which have enabled her to effectively mitigate the countrys rapidly growing energy need. As at 1st January 1999, Malaysias natural gas and crude oil reserves stood at about 86 trillion cubic feet and 4 billion barrels, respectively.

While efforts to increase these hydrocarbon reserves were being intensified, Malaysia also embarked on programmes to better manage the country's growing appetite for energy. With its natural gas reserves almost four times as big as its crude oil reserves, initiatives naturally centred on boosting the use of natural gas to displace oil as the country's main source of energy. This objective was achieved in 1994, owing primarily to the completion of the trans-peninsula natural gas pipeline grid, popularly known as the Peninsular Gas Utilisation project, or PGU.

Among the several initiatives considered by PETRONAS, the national oil company which was entrusted with the responsibility to manage Malaysia's oil and gas reserves, is the District Cooling System using natural gas as the primary source of energy. Apart from ensuring that the nations natural gas reserves are being used in the most effective manner, the Gas District Cooling System, coupled with Cogeneration, also presents Malaysia and PETRONAS with the opportunity to obtain maximum value for the countrys natural gas resources. The discussions which follow are aimed at sharing the information regarding the Gas District Cooling and Cogeneration system, its benefits, and the company which is actively promoting and implementing this system. 2. THE DISTRICT COOLING SYSTEM 2.1 A District Cooling System, or DCS, essentially involves the pooling or centralising of the thermal media (chilled water) required for the air-conditioning of buildings within a specific area or district and producing the chilled water required from one central plant. The chilled water produced from the plant is then distributed to the respective buildings via a network of distribution pipeline.

The DCS is actually not a new system in the industrialised countries, having been implemented since the sixties. However, in Asia, the use of the system has been confined mainly to Japan, with a handful being implemented in Malaysia, Singapore, Hong Kong, and Taiwan. However, almost all the DCS already in operation outside Japan are electrically driven. Thus, it is therefore not surprising that till today, the gas based DCS, or Gas District Cooling (GDC), is still a relatively new system in Asia. Equally important is the lack of awareness of the system and its benefits within the region.

2.2 The low level of acceptance for the GDC system today in most countries is mainly attributed to the difficulty in obtaining supply of natural gas in the major cities and commercial centres. In some countries, the use of this system is seriously hindered by the subsidised electricity tariff and high natural gas price. It is therefore emphasised that these two factors are critical when determining the viability of the GDC system. Otherwise, the implementation of such system would not be able to provide the investors with the desired return on investment for such project.

Figure 1. Typical Layout of a District Cooling Plant

3. DIFFERENCE BETWEEN GDC SYSTEM AND CONVENTIONAL SYSTEM

3.1 The fundamental difference between the GDC system and the conventional district cooling system is in the way chilled water is being produced. The conventional system uses only electrical driven chillers, namely electrical centrifugal chillers (ECC), which is powered by electricity obtained from the national grid to drive the compressors which utilise the refrigerant gas, R134, to cool the water down to the desired temperature, usually between 4o to 6o Celsius.

3.2 The GDC system on the other hand provides greater flexibility in the choice of system configuration to produce the chilled water. To power the chillers, the GDC system provides two options. The first method involves burning of the gas in the direct fired absorption chiller system to produce chilled water. In the second mode, natural gas is used to fire the boilers to produce steam which is then used to drive the steam turbine centrifugal chillers (STC), or steam absorption chillers (SAC). For the STC, the refrigerant R134 is used to produce the chilled water, whereas in the case of the directly fired absorption chillers and SAC, the chemical lithium bromide is being used. The choice of chiller to be used depends entirely on the temperature of the chilled water required by the customers. The STC is able to produce chilled water at a very low temperature of 3.3o Celsius, whereas the SAC can only produce chilled water not lower than about 6.0o Celsius.

4. GAS DISTRICT COOLING WITH COGENERATION -THE SYSTEM OF THE FUTURE 4.1 When the district cooling system was first implemented at the Kuala Lumpur City Centre Development, or KLCC, in 1995, the chillers used were all ECCs. The plant was configured as such because at that time, there was no natural gas supply into the city. However, when natural gas supply was made available in 1997, STCs were installed in the plant. With the STCs, the plant is able to operate on dual mode, using natural gas and electricity from the national grid. 4.2 Although the GDC technology is still new in Malaysia, efforts were swiftly carried out to further improve the efficiency of the system. The need to show profitability of the plant was also an important pressing factor. Apart from reducing operating cost, ways to generate additional revenues were also explored. Various opt ions were subsequently studied to optimise the plant's operations, and even the manner the customers operate their air handling units (AHU) were also examined. At the plant, efforts were focused mainly on how best the steam required can be generated. This initiative eventually led to the feasibility study to implement cogeneration in the plant, especially since the electricity generated can also be used to meet the plant's internal needs, with any excess to be sold to neighbouring buildings.

CHILLED WATER SUPPLY PIPE

CHILLED WATER RETURN PIPE

GAS DISTRICTCOOLING PLANTGAS DISTRICT

COOLING PLANT

OFFICE TOWEROFFICE TOWEREDUCATIONAL

FACILITIESEDUCATIONAL

FACILITIES

ENTERTAINMENT AND RETAIL CENTRE

ENTERTAINMENT AND RETAIL CENTRE

4.3 Admittedly, cogeneration technology is not a new technology. As most of us are aware, cogeneration forms the basis for combined cycle technology in power generation, and in district heating systems. However, until today, cogeneration is still rarely adopted, except in Japan and maybe a few Western countries. The primary reason as mentioned earlier was the difficulty in obtaining natural gas supply. 4.4 When considering cogeneration as an option to configure a GDC system, three factors are taken into account, namely: the volume of chilled water required by the customers; the amount of steam needed to drive the SACs or STCs; and finally the chilled water demand profile. 4.5 The volume of chilled water required is either given by the customers or calculated based on the net floor area of the buildings within the district which is to be supplied. Based on the volume of chilled water required, the number and size of SAC/STC needed are then determined. Subsequently, the amount of steam needed to drive the STCs or SACs are calculated based on the equipment's technical specification provided by the manufacturer. For example, a 5,000 refrigerant tonne (RT) STC would require some 21 tonnes of steam per hour. Based on the plant's total steam requirement, the number of gas turbine generators (GTGs) needed to generate the steam are then determined. This process involves calculating the amount of steam which can be generated by a particular GTG, as provided by the manufacturer, and dividing this figure with the plant's total steam requirement. The number of GTGs determined is then finalised by studying the customers' chilled water demand profile. This study on energy balance is critical in ensuring that the steam from the GTGs matches the amount required by the chillers (note: the exhaust heat from the GTG is used to fire boilers by the use of a Heat Recovery Steam Generator). Otherwise, if a mismatch occurs, the GTGs would have to be operated on a part load or on an open cycle mode during the non-peak hours, when the buildings either require minimum load or even zero load; thereby resulting in an inefficient operation. 4.6 In cases where the night load is very low and the steam required allows installing the minimum number of GTGs to meet the plant's internal use only, the balance of the steam required would have to be supplemented by auxiliary boilers.

Figure 2. Typical System Configuration of a Gas District Cooling and Cogeneration System

STEAM

GAS

G

GAS

GAS TURBINE

GENERATOR

HEAT RECOVERY

STEAM GENERATOR

STEAM

AUXILIARY GAS

BOILER

STEAM -DRIVENCHILLERS

CHILLEDWATER

CUSTOMER

NATIONAL POWER GRID33KV

11KV

33/11KV

CUSTOMERIN PLANT USE

5. BENEFITS OF THE GDC SYSTEM 5.1 The benefits of the GDC cogeneration system are as follows: 5.1.1 Savings in Capital Cost The most important benefit which the customers would derive from the GDC system is savings in capital expenditure. By linking the building to the district cooling system, the building owner does not have to invest in buying the chillers, cooling towers, and all auxiliaries for producing chilled water. 5.1.2 Savings in Operating Cost Building owners also need not keep a team of personnel to operate and maintain the chillers and cooling towers. Such reduction in manpower, spares and chemicals costs, which are recurring in nature, also result in significant savings. 5.1.3 Optimise Building Space Since the buildings do not need any chillers and cooling towers, significant savings in building design and reduced build-up can be achieved due to reduced construction cost. The space allocated for the chiller room can also be converted and thereafter either be leased out or sold, thereby generating additional revenue to the building owners. 5.1.4 Improve Aesthetic Appearance With the absence of cooling towers and exhaust stack, the buildings would have a wider and better range of design. The improved appearance of the buildings would therefore enhance the value of the property in the development; thereby increasing the asset value to the owners. 5.1.5 Higher Efficiency Factor With its on-site generation and use of exhaust heat to produce chilled water, the GDC system enables achieving up to 75% overall systems efficiency compared to about 40% for the conventional electrical driven system. Moreover, by generating its own power, the GDC/ Cogeneration system reduces stress on the national power grid.

Figure 3. Comparison between GDC/Cogeneration System and Conventional System

NATURAL GAS CO-GENERATION SYSTEM

FUEL ENERGY INPUT : 100%

ELECTRICAL ENERGY : 30 % USABLE HEAT : 40 %

WASTE HEAT : 30 %

TOTAL USABLE ENERGY : 70 %

GAS TRANSMISSION PIPELINE

GAS ENGINE/TURBINE GENERATOR

ELECTRICAL ENERGY POWER

THERMAL ENERGY(CHILLED WATER)

CONVENTIONAL GENERATION SYSTEM

FUEL ENERGY INPUT : 100%

ELECTRICAL ENERGY TRANSMITTED : 39%

WASTE HEAT : 61% TRANSMISSION LOSS : 4%

USABLE ELECTRICAL

ENERGY : 35 %

POWER STATION(GENERATION EFFICIENCY : 39%) POWER LINE

5.1.6 Higher System Reliability Compared to the conventional system which depends entirely on the power grid for its electricity, the GDC/Cogeneration system has two sources of power supply, namely electricity generated internally and backup from the power grid. Customers therefore enjoy a much higher degree of reliable power and chilled water supply. 5.1.7 Transfer of Technology For Malaysia, the GDC cogeneration system also provides a valuable opportunity for its people to acquire new technology. The GDC cogeneration technology is very complex and sophisticated and encompasses practically all avenues of engineering, such as civil, mechanical, electrical, and instrumentation. 5.1.8 Provide Opportunity to Pipe Gas to the City Centre The GDC cogeneration plant at Kuala Lumpur City Centre acted as an anchor customer which provided the much needed load to bring natural gas to the city. The sizeable volume of natural gas required by the plant, with a projected peak demand of almost 12 mmscfd in year 2000, enhanced the economic viability of investing in a natural gas distribution network for the city. Today, almost all the hotels neighbouring the KLCC Development use piped natural gas for cooking and to meet its hot water requirements. 5.1.9 Environment-Friendly System The use of water as the refrigerant and lithium bromide as the absorber in the SACs makes the GDC system environment friendly. Furthermore, the absence of chillers, cooling towers and exhaust stacks in the development and complexes significantly reduce noise and water drift pollution in the area.

6. INTRODUCTION TO GAS DISTRICT COOLING (M) SENDIRIAN BERHAD Gas District Cooling (Malaysia) Sendirian Berhad (GDC(M)) is a subsidiary of PETRONAS. The company, which was incorporated in June 1993, started off initially as a joint venture between PETRONAS and a consortium of established Japanese companies, called TGMM (Malaysia) Sendirian Berhad. The consortium comprises Mitsubishi Corporation, Mitsui & Co. Ltd., and Tokyo Gas Co. Limited. Although PETRONAS initially held only 60% equity in GDC(M), it subsequently bought a further 35% equity from the Japanese consortium in 1998, thereby bringing its equity to about 95%. Having gained the technology and skill needed to undertake new projects and operate existing plants, GDC(M) is being managed and operated totally by Malaysians since the middle of 1998. Since completing its first plant at the KLCC in 1996, GDC(M) has since implemented another 2 projects, one at the Kuala Lumpur International Airport and the other at the New Federal Government Administrative Centre in Putrajaya, which is about 40 kilometres south-west of Kuala Lumpur. The company's total chilled water production capacity today is 77,500RT whilst its electricity generating capacity now stands at 68MW.

7. GAS DISTRICT COOLING PROJECTS IMPLEMENTED IN MALAYSIA 7.1 GDC COGENERATION PLANT AT THE KUALA LUMPUR CITY CENTRE (KLCC) The GDC plant at KLCC was constructed in 1994 and was meant to provide the chilled water needs of the buildings within the KLCC Development. The plant, which was completed in 1996, now has a total chilled water production capacity of 30,000RT, comprising 3 chillers each of STC and ECC, each with a production capacity of 5,000RT. With the sizeable steam required by the chillers, the plant is able to easily accommodate 4 GTGs with a total electricity generating capacity of about 28MW.

To distribute the chilled water within the development, the plant employs a looped chilled water distribution network with the pipeline size ranging between 48 inches and 36 inches. The temperature of the chilled water supplied to the buildings within the KLCC is about 4oCelsius, whilst the desired return temperature is about 14oCelsius.

In essence, the GDC/Cogeneration plant at KLCC was developed in 3 distinct phases. The first stage involving primarily ECC chillers with 15,000RT capacity was completed in mid-1996. The second, which involves the installation of 3 units of 5,000RT STCs and 2 GTGs with capacity of 8MW was completed in mid-1997. The third stage, which was completed in late 1999, involves the installation of 2 units of 10MW GTGs, and the related cogeneration equipment.

7.2 GDC/COGENERATION PLANT AT THE KUALA LUMPUR INTERNATIONAL AIRPORT (KLIA)

The GDC/Cogeneration plant at KLIA was secured in 1996 through competitive bidding which involved several established international companies. Despite being very new to the business, GDC(M) was indeed honoured when our bid was adjudged the best both technically and commercially.

Completed in early 1998, the GDC/Cogeneration plant has a total chilled water production capacity of 30,000RT, which is needed by the airport to provide the required cooling load for a total passenger traffic of 25 million passengers per annum. To meet the required chilled water supply temperature of 6oCelsius, the plant utilises 12 units of SACs each with a capacity of 2,500RT. For the airport's power requirement, the plant is equipped with 2 units of 20MW GTGs. To distribute the chilled water to the airport's Main Terminal Building, which is located 4 km away, and associated Airport Facilities, a total of 16 km of pipes have been laid.

7.3 GDC PLANT AT PUTRAJAYA

Having proven our capability to build, own and operate the GDC/cogeneration plants at KLCC and KLIA, the Government of Malaysia in 1996 awarded to GDC(M) the exclusive rights to provide chilled water supply to the whole of the Putrajaya Development. GDC(M) subsequently began construction of its first plant in Putrajaya, in late 1996 and the plant was completed in late 1998. This plant is located in the Government Precinct or Precinct One, which only houses buildings occupied by the Federal Government.

Due to the staggered development of the Putrajaya area, the GDC plant was also constructed and configured to match the phased build-up of the chilled water demand. Initially, the plant was configured with 2 units of 1,250RT electrical chillers and a thermal storage system with maximum capacity of 2,500RT. This is the first time that the plant is using the thermal storage system, and it is primarily meant to reduce the capital investment in view of the uncertainty which surrounds the development of Putrajaya due to the economic crisis which hit Malaysia since mid-1997. Moreover, supply of natural gas was only available in Putrajaya in late 1999.

With natural gas readily available, GDC(M) subsequently installed 5 units of SACs each with a capacity of 2,500RT. At present, in tandem with the increased chilled water requirement, GDC(M) is installing another 2 units of SACs each with a capacity of 2,500RT. Additionally, to meet the higher power requirement in the plant, GDC is now installing 2 units of GTGs, each with a capacity of about 4MW.

To distribute the chilled water, GDC(M) has installed a network of distribution pipeline totalling about 4 km, with a diameter of 36 inches. The required supply temperature is about 6oCelsius, with the return temperature set at about 14oCelsius.

8. PROJECTS BEING IMPLEMENTED AND FUTURE PROJECTS 8.1 PROJECTS UNDER IMPLEMENTATION 8.1.1 University Technology PETRONAS, Tronoh, Perak The university, which is wholly-owned by PETRONAS, will have about 6,000 students when it is completed in late 2001. The GDC/Cogeneration plant, which will meet the chilled water and electricity requirement for the university, however will need to be completed earlier in mid-2001 to enable the various utilities to be commissioned. Initially, the plant would have a chilled water production capacity of about 4,000RT and would be capable of generating some 7MW of electricity. However, by year 2006, the plants chilled water and electricity production capacity would be further increased to about 7,000RT and 11MW, respectively, to meet a higher student population of about 11,000. 8.1.2 Plant No. 2, Putrajaya, Selangor This plant will serve the chilled water needs of another area to be developed in Putrajaya, called Precinct Two. This area is located in a man-made island called the Core Island, which is made up of altogether 3 precincts, namely Precincts Two, Three, and Four. The Core Island shall house a mix of Government offices and commercial complexes. To avoid sporadic digging in the Core Island, all utilities, including GDC(M)s chilled water distribution pipes, are required to be installed in a Common Utility Trench. The GDC(M)s plant at Precinct 2 is scheduled to be completed in late 2001, and will have an initial chilled water production capacity of about 4,000RT. When fully developed in 2007, the plant is expected to have a total production capacity of about 30,000RT. 8.2 FUTURE PROJECTS 8.2.1 Tanjung Langsat Industrial Complex, Johor Bahru, Johor The Tanjung Langsat Industrial Park spans over an area of almost 2,000 hectares. The Park is meant to house petrochemical and other similar medium and heavy industries. Although initial electricity and steam requirement is fairly small, the quantity is projected to increase to about 120MW of electricity and about 500 tonnes/hour of steam by year 2020. GDC(M) is building a Cogeneration plant to supply electricity and steam to the Park. The plant, which is scheduled to be completed by October 2000, would have an initial capacity to produce some 9MW of electricity and 15 tonne/hour of steam. Apart from pursuing projects within the country, GDC(M) is also considering proposals to build, own and operate district cooling and cogeneration plants in other countries, such as Indonesia and the United Arab Emirates. 9. CONCLUSION The Gas District Cooling and Cogeneration system enhances the efficiency of the process to produce chilled water and generate electricity. Adoption and implementation of this system in developing countries with fast growing economies would enable such countries to reduce their energy consumption, especially oil, and provides valuable opportunity to develop natural gas distribution network in densely populated and heavily industrialised areas.

For countries with significant oil and natural gas reserves, the adoption of the GDC/Cogeneration system in the production of chilled water and generation of electricity helps to add and maximise the value of their natural gas reserves, whilst allowing for more oil to be exported to generate foreign exchange revenue. As the leading GDC/Cogeneration company in Malaysia, Gas District Cooling (Malaysia) is seeking opportunities to further expand its operations, both locally and abroad, and is ready to consider proposals to undertake projects to supply chilled water, electricity and steam to industrial parks and commercial complexes.

HOMEWOC6 PRESENTATIONP-604 IMPLEMENTATION OF GAS DISTRICT COOLING AND COGENERATION SYSTEMS IN MALAYSIAABSTRACTRESUME1. INTRODUCTION2. THE DISTRICT COOLING SYSTEM3. DIFFERENCE BETWEEN GDC SYSTEM AND CONVENTIONAL SYSTEM4. GAS DISTRICT COOLING WITH COGENERATION -THE SYSTEM OF THE FUTURE5. BENEFITS OF THE GDC SYSTEM6. INTRODUCTION TO GAS DISTRICT COOLING (M) SENDIRIAN BERHAD7. GAS DISTRICT COOLING PROJECTS IMPLEMENTED IN MALAYSIA8. PROJECTS BEING IMPLEMENTED AND FUTURE PROJECTS9. CONCLUSION

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