Spatial and temporal variation in domestic biofuel consumption rates and patterns in Zimbabwe: implications for atmospheric trace gas emission

An ecologically nationwide and all-year-round domestic biofuel consumption study was conducted in Zimbabwe from January 1996 to March 1997. The study aimed at (a) establishing the determinants and magnitudes of spatial and te mporal variations in biofuel consumption rates, (b) estimating the overall mean national rural and urban consumption rates, and (c) estimating the con tribution of domestic biomass burning in Zimbabwe to the emission of atmosp heric trace gases. The main source of spatial variation in biofuel consumpt ion rates was found to be settlement type (rural or urban). Within a settle ment type, per capita consumption rates varied in time and space with house hold size, ambient temperature, and physical availability. In rural areas w ood and agricultural residues were consumed at national average rates of 1. 3 +/- 0.2 and 0.07 +/- 0.01 tonnes capita(-1) year(-1), respectively. In ur ban centres wood was consumed at an average rate of 0.4 +/- 0.26 tonnes cap ita(-1) year(-1). These consumption rates translate into emission outputs f rom Zimbabwe of 4.6 Tg CO2-C year(-1), 0.4 Tg CO-C year(-1), 5.3 Gg NO-N ye ar(-1) 14.5 Gg CH4-C year(-1), 24.2 Gg NMHC-C year(-1), 2.9 Gg organic acid -C year(-1) (formic and acetic acids) and 48.4 Gg aerosol-C year(-1). For C O2, CO, and NO, these domestic biofuel emissions represent 41 +/- 6%, 67 +/ - 6%, and 8 +/- 1%, respectively, of the total output of all sources evalua ted and documented in Zimbabwe to date. This means that of the studied sour ces, domestic biomass burning is the major source of CO2 and CO emission in Zimbabwe. (C) 1999 Elsevier Science Ltd. All rights reserved.