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Greenhouse gas emissions of biofuels: improving Life Cycle Assessments by taking into account local production factors

Abstract : Life Cycle Assessments (LCA) make it possible to check for all polluting emissions and potential environmental impacts of biofuels throughout the product chain. However, LCA emission factors only give an estimate of average potential emissions, notably not considering the local kinetics of N2O emissions, the most important agricultural greenhouse gas. Our objective was first to analyse how soil compaction affects N2O emissions by combining field experiments and modelling. With automatic chambers in sugar beet fields, we measured cumulative N2O emissions of 944-977 g N-N2O ha-1 in uncompacted plots and 1,448-1,382 g N-N2O ha-1 in compacted plots in 2007-2008 respectively. Greater soil compaction led to higher N2O emissions by inducing favourable anoxic conditions for denitrification. We modified the NOE model to better simulate nitrification and account for variations of N2O fractions over total products. The modified model (NOE2) better predicted nitrification rates and N2O emissions post fertilization but still underestimated total emissions. The determinism of dry-wet cycle impacts on N2O emissions should be further investigated. We used the modelled data to produce our local LCA and test the effects of local pedo-climatic conditions and management practices. Miscanthus ethanol had overall much lower potential environmental impacts than gasoline or sugar beet ethanol, allowing for savings of some 82-85% greenhouse gas and around 90% of fossil resources compared to gasoline. Sugar beet ethanol would lead to smaller savings of 28-42% greenhouse gases and 20-28% of fossil resources per MJ compared to gasoline depending on the local production factors during biomass growth.
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https://pastel.archives-ouvertes.fr/tel-00453003
Contributor : Cécile Bessou <>
Submitted on : Wednesday, February 3, 2010 - 4:33:37 PM
Last modification on : Monday, October 19, 2020 - 11:07:51 AM
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  • HAL Id : tel-00453003, version 1
  • PRODINRA : 245255

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Cécile Bessou. Greenhouse gas emissions of biofuels: improving Life Cycle Assessments by taking into account local production factors. Earth Sciences. AgroParisTech, 2009. English. ⟨NNT : 2009AGPT0067⟩. ⟨tel-00453003⟩

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