The upfront carbon debt of bioenergy

May 2010

This report summarizes the future scenarios of bioenergy demand by 2020 and the potential bioenergy production, taking into account different fuel mixes. It discusses and gives guidance to assess the real carbon neutrality (CN) of bioenergy when a medium term climate mitigation goal is considered. The main focus is on woody biomass used for bioenergy. Finally, policy options to include the bioenergy upfront carbon debt in the accounting systems are presented. The CN factor is defined as the ratio between the net reduction/increase of carbon emissions in the bioenergy system and the carbon emissions from the substituted reference energy system, over a certain period of time. The CN is time dependent and it includes emissions from carbon stock changes.
This study shows that different sources of biomass for bioenergy can have very different climate change mitigation potentials according to the time horizon that is considered, by assessing the development of their CN over time. There is forest biomass that can produce a GHG benefit in the atmosphere from the beginning of its use but it is not carbon neutral. Other sources of woody biomass will require a long time before producing a GHG benefit in the atmosphere, while some other sources can be carbon neutral from their initiation.
In the current accounting of GHG emissions in the climate change policy framework, there are two major gaps concerning the use of bioenergy. The first is a gap in spatial coverage. This gap resulted from adoption of an inventory methodology designed for a system in which all nations report into systems in which only a small number of countries have emission obligations, i.e., the Kyoto Protocol (KP) and the Emission Trading Scheme (EU-ETS). The second is a failure to differentiate between a system in which very long time horizons are relevant – efforts to mitigate climate change over the long term – and systems concerned with shorter-term horizons such as the EU 2020 and 2050 targets. Since the KP adopted the UNFCCC Inventory Guidelines without considering these differences, current accounting systems’ difficulties in addressing the
time-dependency of biomass’ carbon neutrality can also be traced to this decision.

By: G. Zanchi, N. Pena, N. Bird (Joanneum Research)

 
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