Energy and nutrients in the human ecology of Hong Kong

Abstract

The input-output and end-use of extrasomatic energy use is reported for 1971. Trends in Hong Kong's energy use are examined over a period of 17 years in relation to the rapidly changing urban setting and alternative sources of energy which may be adopted in the future. Forty per cent of Hong Kong's energy input is lost in conversion processes, the end-use of energy is inefficient and potential for conservation and recycling is considerable. Upto 15% of total energy use could be supplied by direct solar irradiation and bioconversion of organic wastes generated in Hong Kong. From a sector end-use analysis of energy use it is clear that Hong Kong is moving towards more energy intensive industry and more energy expensive transport. Also,new commercial and residential buildings are heavily reliant on energy-use to remain fit for human use. An analysis of spatial and temporal patterns of energy use show a range of intensity of energy use from 0.02 x 10⁸ MJ/km² in rural areas to 109.46 x 10⁸ MJ/km² in heavy industrial/residential areas. Energy consumption is 26% higher in summer than in winter. Artificial heat generation over all Hong Kong is 1.7% of mid-summer and 2.3% of mid-winter incoming solar radiation; but reaches double incoming solar radiation over 24 hour periods in some parts of the urban area. It is demonstrated, through a study of energy use in the Hong Kong food system, that the energetic efficiency of food production in the Hong Kong region has decreased by 10 to 250 times in the past 40 years. The energy input-output ratio for all Hong Kong crop production in 1971 was 0.8:1; but where high technology production modes were practiced the ratio was 7.6:1. It is estimated that 40-50% of the energy invested in the Hong Kong food system could be conserved without a decline in crop production. A nutrient balance is established for the Hong Kong ecosystem. Losses of nutrients in human food are upto 20% of total input for important nutrients. The flow of phosphorous in the Hong Kong food system is examined in detail. Here it is shown that about 3,600 tonnes of phosphorous are lost from the Hong Kong food system each year. From a study of the land based forage area demand, the average Hong Kong resident is shown to consume a diet which requires only half the land area to produce as the average Sydney resident. The nutrient balance data is presented in terms of apparent consumption of human food and is compared with the socio-economic distribution of nutrients in the Hong Kong community. For most important nutrients apparent consumption is at the level of western populations. However, both the intake of calcium and somatic energy are found to be deficient in comparison with recommended intake, particularly for low socio-economic groups. The likelihood of biological and cultural adaptation to these apparent dietary deficiencies is discussed. Finally the interaction between energy use and individual health and well-being is examined. Data presented supports the conclusion that happiness and life-enjoyment improves with increases in individual energy use. Evidence is also presented to show how energy use degrades the physicochemical environment of Hong Kong leading, potentially, to an increase in human maladjustment. Show more