CO2 emissions from biomass combustion Accounting of CO2 emissions from biomass under the UNFCCC

Abstract Many Parties to the United Nations Framework Convention on Climate Change (UNFCCC) are envisaging the use of significant amounts of biomass as a primary source in their energy supply. The present greenhouse gas (GHG) emission inventory guidelines, based on methods and approaches originally proposed by the IPCC in the 1990s do not add the CO2 emissions from the combustion or incineration of these biogenic fuels to national total emissions, as it is assumed these emissions reverse recent CO2 removals from the atmosphere during photosynthetic growth of the biomass, largely within the Party’s own boundaries. In a national annual inventory under the UNFCCC, the biomass carbon harvested in a specific year is balanced against the biomass carbon oxidation processes addressed in the energy and waste sectors of GHG inventories. The CO2 emissions from biomass oxidation in the present Intergovernmental Panel on Climate Change (IPPC) inventory approach are accounted for by the country harvesting the biomass via the subtraction of the harvested biomass from C pools on their lands. This harvested biomass carbon is implicitly assumed to be oxidized both in the year and the country of harvest, regardless of whether this is factual. In the case of biomass exports, the CO2 emissions from the combustion/oxidation of this harvested biomass are not included in the national totals of the country where the biomass is used, as under the present approach this would lead to double counting on the global scale. With the increasing use of biomass on industrial scales, the assumptions underlying this approach start to introduce material inaccuracies on a national scale (versus global). Biomass combustion may no longer be negligible compared with fossil fuel combustion as biogenic fuels are increasingly traded internationally. In this paper, we review the present IPCC carbon mass flow approach and propose a change in the reporting and accounting methods that has the potential to address this national GHG emissions reporting issue.