Department of Civil and Environmental Engineering, University of Virginia, 351 McCormick Road, P.O. Box 400742, Charlottesville, VA 22904, United States.
Department of Systems and Information Engineering, University of Virginia, 151 Engineer's Way, P.O. Box 400747, Charlottesville, VA 22904, United States.
Bioresour Technol. 2016 Oct;218:196-201. doi: 10.1016/j.biortech.2016.06.058. Epub 2016 Jun 18.
The environmental impacts of algae biofuels have been evaluated by life-cycle assessment (LCA); however, these analyses have overlooked nitrous oxide (N2O), a potent greenhouse gas. A literature analysis was performed to estimate algal N2O emissions and assess the impacts of growth conditions on flux magnitudes. Nitrogen source and dissolved oxygen concentration were identified as possible key contributors; therefore, their individual and combined impacts were evaluated using bench-scale experiments. It was observed that maximum N2O emissions (77.5μg/galgae/day) occur under anoxic conditions with nitrite. Conversely, minimum emissions (6.25μg/galgae/day) occur under oxic conditions with nitrate. Aggregated N2O flux estimates were then incorporated into a LCA framework for algae biodiesel. Accounting for "low" N2O emissions mediated no significant increase (<1%) compared to existing GWP estimates; however, "high" N2O emissions mediate an increase of roughly 25%, potentially jeopardizing the anticipated economic and environmental performances of algae biofuels.
藻类生物燃料的环境影响已经通过生命周期评估 (LCA) 进行了评估；然而，这些分析忽略了一氧化二氮 (N2O)，一种强效温室气体。进行了文献分析以估算藻类 N2O 排放，并评估生长条件对通量大小的影响。氮源和溶解氧浓度被确定为可能的关键因素；因此，使用台架实验评估了它们的单独和综合影响。结果表明，在缺氧条件下与亚硝酸盐一起会发生最大的 N2O 排放 (77.5μg/藻/天)。相反，在有氧条件下与硝酸盐一起会发生最小的排放 (6.25μg/藻/天)。然后将汇总的 N2O 通量估算值纳入藻类生物柴油的 LCA 框架中。与现有 GWP 估算值相比，考虑“低”N2O 排放不会导致显著增加 (<1%)；然而，“高”N2O 排放会导致增加约 25%，可能危及藻类生物燃料预期的经济和环境性能。
