What Are the Rules for Biofuel Carbon Accounting?

Abstract

Most quantitative assessments of biomass fuels or biofuels assume that bioenergy is inherently carbon neutral, that biogenic emissions of carbon dioxide should be excluded from a carbon footprint. This 'carbon neutral' assumption makes an enormous difference in carbon accounts and in the policies that those accounts would suggest. For instance, if harvested logs burnt as fuel are considered carbon neutral, their carbon footprint is far lower than that of natural gas. However, if the logs' biogenic carbon emissions are counted, then their carbon footprint is much higher than gas's. Moreover, this can lead to absurd conclusions. If carbon neutrality is presumed, it makes no difference to a carbon footprint if a forest is standing or if it has been chopped down for fuel wood. Since the mid-1990s, some researchers have contradicted the 'carbon neutral' assumption, and their view that biogenic emissions should be counted has begun to attract significant attention of policy makers. This paper reviews the history and current state of biogenic-carbon accounting rules, including the ISO/CEN rules being developed under the EU Renewable Energy Directive. Without taking sides, it will define the debate for researchers and policy-makers, reflect on its significance and suggest possible means of resolution.