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HONG KONG URBAN COUNCIL
householders in the urban area, if for any reasons there is a bottle neck in the disposal side of the cycle, the function of the UC will be adversely affected. It is for this reason that the UC should take a sensible look at the best alternative for the disposal of domestic wastes.
The 1989 Review
Earlier in March 1989, we had a comprehensive review of our strategy of waste disposals in HK at that time, the decision was taken to phase out all outdated incinerators, and instead, to concentrate on landfill as the only means for final waste disposal. It was also decided that transfer stations should be built at strategical locations for the interim holding of domestic wastes before delivery to the landfill sites. Such decisions were taken because the high-tech incinerators, though caused the least environmental pollution, were prohibitively costly to build and to operate. Furthermore, the new tech needed to be time tested.
Why The Debate?
The new experiences from the use of high-tech incinerators learned in the various study visits made by the UC over the past year to Singapore, Japan, Macau, Vancouver and Washighton, there had been a large volume of information accumulated which pointed to the direction that it is time for us to rethink our strategy to adopt incineration as a supplementary means for the final disposal of domestic wastes in Hong Kong. This is certainly opportune after the Legco had a lively debate on environmental issues and policies in Hong Kong last week.
The Rationale For The Rethink
Heretofore, the grounds mentioned for rejecting the incinerator option were on three main areas, namely.
1. Environmental pollution, both air and soil, especially with the older type of incinerators and when they were not well maintained.
Over the past few years, experiences in overseas countries have proved that incineration causes no environmental pollution, in fact, for the disposal of domestic wastes, it is environmentally more friendly than landfill as demonstrated by the Burnaby report. The tall chimney in the incineration plant is not for the purpose of taking away the polluted air emission, for there is not any. Rather it is designed for taking the hot air to a higher level above the ground so that the hot air will be diluted in temperature, and will not affect the surrounding with any hot air.
On the other hand, for the disposal of domestic wastes, the landfill option actually turned out to cause more environmental pollution than originally anticipated. For example, there is a larger volume of carbon dioxide emission from the landfill which will aggravate the green house effects and global warming. The dissolution of toxic chemicals and insecticides commonly used in the house-holds will find their way into the natural water system which will be harmful to human health, if inadvertently used for human consumption and agriculture. In addition, emissions of toxic gases such as methane will pollute the surrounding area near the landfill.
2. The requirement for pre-separation of wastes before incineration.
Such step was not found to be necessary with the newer type of incinerators, whereby plastics, batteries, heavy metals or other toxic substances could be accommodated without undue effects on the operation of the incinerator and without the emission of any toxic gases to the atmosphere.
The highly wet nature of our domestic wastes will not affect the amount of energy produced as with special design, air can be blown onto the waste on the crate before being delivered into the furnace. The yield in caloric value from our incinerated waste is high as judged by our past HK experiences.
3. The incinerator option is far too costly to install and equally costly to operate. This concept might have been arrived at, when all aspects of costing were not being taken into account.
The cost for landfill option should include cost of land and construction of landfill and transfer stations, transportation costs from transfer stations to the landfill sites, maintenance costs of the transfers stations, transportation cost from refuse collection points to transfer stations.
For the incinerator option, the costs should include costs for construction and maintenance of the incinerators, the transportation of the 30% of bottom ash which can be utilized as roadbase and aggregate for paving and can make excellent landfill cover and roads. In the end, only 3% of the fly ash of the incinerated waste will need landfill for disposal. The use of incinerator will extend the life span of landfill by at least ten times. The net-costs of the operation are arrived at by deducting the revenue receivable from the sale of electricity from the total costs. As its initial installation costs is high, it would be more accurate to compare the total costs over the life span of the incinerators which cover over a period of about 20 years. In USA, there is such a legislation to get the co-operation of the electricity company to buy electricity from the incinerator plant, especially if they are given a discount in price on the rates charged to the retail customers.
Costing Exercises In Dollars Terms
In the cost analysis of the two options, it is noted that the total costs seemed to be about twice more expensive for the incinerator option, though the costs lower appreciably after the 20th year, when the initial costs for the incinerators have totally been depreciated. It is also noted that when the sale revenue of electricity is taken into account, the net costs for the two options showed that the incinerator option is in fact cheaper from the very beginning.
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