Department of Agroecology, Aarhus University, Blichers Alle 20, 8830 Tjele, Denmark.
Department of Agroecology, Aarhus University, Blichers Alle 20, 8830 Tjele, Denmark.
Sci Total Environ. 2019 Jun 25;671:180-188. doi: 10.1016/j.scitotenv.2019.03.257. Epub 2019 Mar 19.
Winter oilseed rape (WOSR) is the main crop for biodiesel in the EU, where legislation demands at least 50% savings in greenhouse gas (GHG) emissions as compared to fossil diesel. Thus industrial sectors search for optimized management systems to lower GHG emissions from oilseed rape cultivation. Recently, pyrolysis of biomass with subsequent soil amendment of biochar has shown potentials for GHG mitigation in terms of carbon (C) sequestration, avoidance of fossil based electricity, and mitigation of soil nitrous oxide (NO) emissions. Here we analyzed three WOSR scenarios in terms of their global warming impact using a life cycle assessment approach. The first was a reference scenario with average Danish WOSR cultivation where straw residues were incorporated to the soil. The others were biochar scenarios in which the oilseed rape straw was pyrolysed to biochar at two process temperatures (400 and 800 °C) and returned to the field. The concept of avoided atmospheric CO load was applied for calculation of C sequestration factors for biochar, which resulted in larger mitigation effects than derived from calculations of just the remaining C in soil. In total, GHG emissions were reduced by 73 to 83% in the two biochar scenarios as compared to the reference scenario, mainly due to increased C sequestration. The climate benefits were higher for pyrolysis of oilseed rape straw at 800 than at 400 °C. The results demonstrated that biochar has a potential to improve the life cycle GHG emissions of oilseed rape biodiesel, and highlighted the importance of consolidated key assumptions, such as biochar stability in soil and the CO load of marginal grid electricity.
冬油菜（WOSR）是欧盟生物柴油的主要作物，该地区的立法要求温室气体（GHG）排放量比化石柴油至少减少 50%。因此，工业部门正在寻找优化的管理系统，以降低油菜种植的温室气体排放。最近，生物质热解随后用生物炭进行土壤改良，在碳（C）封存、避免基于化石的电力以及减少土壤氧化亚氮（NO）排放方面显示出了减少 GHG 的潜力。在这里，我们使用生命周期评估方法分析了三个 WOSR 情景的全球变暖影响。第一个是丹麦平均油菜种植的参考情景，其中将秸秆残茬还田。其他两个是生物炭情景，其中油菜秸秆在 400 和 800°C 两种工艺温度下热解为生物炭，并返回田间。避免大气 CO 负荷的概念用于计算生物炭的 C 封存因子，这导致了比仅从土壤中剩余 C 计算更大的缓解效果。与参考情景相比，两个生物炭情景下的 GHG 排放量减少了 73%至 83%，主要是由于 C 封存的增加。油菜秸秆在 800°C 热解的气候效益高于 400°C。结果表明，生物炭有可能改善油菜生物柴油的生命周期 GHG 排放，并强调了统一关键假设的重要性，例如生物炭在土壤中的稳定性和边际电网电力的 CO 负荷。
