Greenhouse-gas emissions from biofuel combustion in Asia

An inventory of biofuel combustion is used to develop estimates of the emis sions of carbon-containing greenhouse gases (CO2, CO, CH4, and NMHC) in Asi an countries. It is estimated that biofuels contributed 573 Tg-C (teragrams of carbon; 1 Tg = 10(12) g) in 1990, about 28% of the total carbon emissio ns from energy use in Asia. China (259 Tg-C) and India (187 Tg-C) were the largest emitting countries. The majority of the emissions, 504 Tg-C, were i n the form of CO2; however, emissions of non-CO2 greenhouse gases were sign ificant: 57 Tg-C as CO, 6.4 Tg-C as CH4, and 5.9 Tg-C as NMHC. Because of t he high rates of incomplete combustion in typical biofuel stoves and cooker s and the high global warming potentials (GWP) of the products of incomplet e combustion (PICs), biofuels comprise an even larger share of energy-relat ed emissions when measured in terms of total GWP (in CO2 equivalents): 38% over a 20-year time horizon and 31% over a 100-year time horizon. Even when the biofuel is assumed to be harvested on a completely sustainable basis t all CO2 emissions reabsorbed in the following growing season), PIC emission s from biofuel combustion account for 4.5% of the total carbon emissions an d 23% of CO2 equivalents on a short-term (20-year) GWP basis. (C) 1999 Else vier Science Ltd. All rights reserved.