Assessing carbon balance trade-offs between bioenergy and carbon sequestration of stumps at varying time scales and harvest intensities
2010
Melin, Ylva | Petersson, Hans | Egnell, Gustaf
Mitigating climate change and securing a supply of energy may be achieved, in part, by substituting fossil fuels with bioenergy from stumps and roots. However, the use of stumps would result in a reduction of the carbon pool and thus, from a greenhouse gas emission perspective, there is a trade-off between using stumps for bioenergy and retaining them in the carbon pool associated with dead organic matter. The objective of this study was to show whether, from a carbon balance perspective and over the short and long-terms, stumps are more important as a source of energy that replaces fossil fuels, or as a carbon sink. The study was based on the estimated bioenergy potential of stumps for three harvest scenarios and the corresponding effects on stump-carbon sequestration, if stump harvesting had been practiced in Sweden during the period 1984-2003. Approximately 30,000 permanent plots from the Swedish National Forest Inventory (NFI) were used for estimates of bioenergy potential. For the scenario “Medium intensity”, the bioenergy potential was estimated to 51PJyr⁻¹ (or 5.7TgCO₂ yr⁻¹). The corresponding carbon sequestration potential from the retained biomass in the ground was 15TgCO₂ yr⁻¹. Using these stumps and roots as bioenergy substituting coal would result in a reduction of emission from coal combustion of 5.0TgCO₂ yr⁻¹. In the short-term, the choice of coal or stumps as an energy source has a minor effect on the gross emissions to the atmosphere but the removal from an increasing stump-carbon pool would slightly favor the use of coal. However, this study indicates that the most effective way of achieving a net reduction of emissions in the long-term is to burn stumps.
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