part 1: overview of cogeneration and its status in asia - Fire

22 Part I: Overview of cogeneration and its status in Asia
whereas hotels may have high loads at nights. When the two loads are combined, a uniform
composite curve may be obtained with very small amplitude.
Besides, there are a number of justifications for grouping together several buildings and
industries in order to meet their different energy services, such as:
- larger cogeneration system and the economies of scale associated with it;
- system expansion to users for whom individual facility cannot be justified;
- improvement in the overall generation efficiency;
- increased reliability and availability of utility services;
- pooling of maintenance personnel and reduction in manpower cost;
- saving of mechanical room space in the user buildings;
- purchase of fuel at more competitive rate;
- better negotiation power for power purchase/sale to the electric utility, etc.
There are, however, a few drawbacks to district heating/cooling, the most important among
them being the high initial investment on the system. The cost of steam/hot water and chilled
water transportation and distribution can also be high. Because of the down-sizing of the
different components installed at the central plant, capital investment cost can in fact be
reduced by 10 to 20 per cent as compared to those which would have been required in the
individual buildings. This takes into account the piping distribution network cost that is not
required in conventional decentralized systems. For instance, a district cooling network is
installed in Paris which includes three chiller plants with a total of 25,500 RT to supply to a
museum, shopping complex, exhibition centre and offices having a total equivalent area
exceeding one million m 2 . Decentralized plants would have required a total capacity of
approximately 34,100 RT to be installed. The district-cooling network has thus helped to
achieve an investment saving of over US$ 8 million for the reduced installed cooling capacity.
2
2.8 Evolution of Package Cogeneration
Cogeneration systems traditionally constituted various components which were ordered and
assembled at the site according to the client’s requirements, mostly matching the thermal
energy needs. The minimum power generation capacity was of the order of a few MW due to
the limited products available in the market, some of the reasons being:
1) Investment cost per kWe is considerably higher for smaller units;
2) Limited financing capabilities of small and medium scale enterprises;
3) Additional investment needed by smaller units to cope with environmental regulations;
4) Unavailability of guarantee for the overall system.
2 R. Caillaud, “District cooling with thermal storage for shifting power loads in south-east Asia”, APEC
Demand-side Management Inter-Utility Liaison Group Meeting, Chiang Mai, 26-29 March 1996.