Poster's note - this helps constrain the environmental impacts of one of the sources of fuel for BECCS that's potentially in lower conflict with the production of food.
http://www.sciencedirect.com/science/article/pii/S0960852416308756 Bioresource Technology 18 June 2016, doi:10.1016/j.biortech.2016.06.058 Re-evaluation of the Global Warming Impacts of Algae-Derived Biofuels to Account for Possible Contributions of Nitrous Oxide Sarah K. Bauer, Lara S. Grotz, Lisa M. Colosi Highlights •LCAs of algae biofuels have overlooked a possible key contributor to GWP: N2O. • Experiments show min N2O emissions under oxic conditions with nitrate N-source. • Experiments show max N2O emissions under anoxic conditions with nitrite N-source. • Min N2O emissions mediate <1% increase in GWP compared to existing estimates. • Max N2O emissions mediate an increase in existing GWP estimated by roughly 25%. Abstract 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 (77.5 μg/g algae/day) occur under anoxic conditions with nitrite. Conversely, minimum emissions (6.25 μg/g algae/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. Keywords Algae biofuels, Nitrous oxide, Greenhouse gas emissions, Life-cycle assessment -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
