Contribution to the Heat Budget in Nairobi Metro-Area by the Anthropogenic Heat Component

Abstract

This study quantifies the ejected waste heat from artificial supplies comprising road transport and industrial, commercial, domestic and metabolic heating activities which may enhance the urban temperatures in Nairobi metro area, taking into account the energy intensity of a given activity and the level of the activity, considering expended fossil and biofuels, electrical energy consumption and human metabolism. Translation of linear source strengths to area averages from the road transport sector yields about 4% of the total anthropogenic energy over the city. The contribution from the road sector is likely to rise to 10.8 W m-2 in 2029 as the City expands. The industrial/commercial sector contributes up to 35.5 W m-2 or 57% of the total anthropogenic energy, and could increase to 284 W m-2 by 2029 due to industrialization and economic growth. Domestic utilities account for up to 13 W m-2, which is 21% of the total anthropogenic energy. Depending on the activity engaged in, human metabolism contributes up to 11.4 W m-2, which is about 18% of the total anthropogenic energy supplies. The sum total area-averaged anthropogenic energy consumption over the city centre is currently small, constituting about 11 to 18% of the global radiation for the warmer and colder seasons, respectively. Notably, only a part of this energy is released into the atmosphere as waste heat as most is used for the intended purposes. If the current trends of rising population, increased motor vehicle density and enhanced industrialization persist, the anthropogenic waste heat ejection would be large enough to alter the heat balance of the study area appreciably in future by 2030.