Some years back Emad Ghafoori and I looked at the life cycle emissions of anaerobic digestion of cattle manure, part of our techno-economic study of AD. We had to assess the emissions of cow patties, and we had assumed that they would be a significant source of methane. We found a study that reported that methane emissions dropped sharply after the first day, and we hypothesized that this was because aerobic bacteria quickly developed on the cow patty and perhaps processed the methane from anaerobic bacteria in the patty, or its precursors.
I have wondered if the same would occur in the arctic, reducing the very scary methane risk to a still substantial CO2 risk. It would make an interesting research project, much as measuring emissions from a cow patty was. As a general comment: anaerobic digestion of manure to produce a gas that is ~60% methane and 40% CO2 works, but is lousy economics if solely done to address GHG mitigation: there are far cheaper ways (measured by dollars per ton of avoided CO2 equivalent) to mitigate. Anaerobic digestion can deal with excessive phosphate in soil (by precipitating it prior to land spreading the digestate), and vastly reduces pathogens and odor. So if one has a phosphate, odor or pathogen problem, it may make sense, but if one is simply trying to mitigate atmospheric GHG components, one gets more benefit for the expense from other approaches. Peter Peter Flynn, P. Eng., Ph. D. Emeritus Professor and Poole Chair in Management for Engineers Department of Mechanical Engineering University of Alberta peter.fl...@ualberta.ca cell: 928 451 4455 *From:* geoengineering@googlegroups.com [mailto: geoengineering@googlegroups.com] *On Behalf Of *Klaus Lackner *Sent:* Thursday, October 5, 2017 5:15 PM *To:* durb...@gmail.com; geoengineering <geoengineering@googlegroups.com> *Subject:* Re: [geo] Warming Permafrost+microbes+sunlight = Co2 I would be afraid that your alternative is methane. Which would not be much of an improvement Klaus *From: *<geoengineering@googlegroups.com> on behalf of Eric Durbrow < durb...@gmail.com> *Reply-To: *"durb...@gmail.com" <durb...@gmail.com> *Date: *Thursday, October 5, 2017 at 10:36 AM *To: *geoengineering <geoengineering@googlegroups.com> *Subject: *[geo] Warming Permafrost+microbes+sunlight = Co2 Although indirectly related to climate engineering, I thought people would find this interesting as the topic of warming permafrost has come up many times. Nature abstract of study showing how certain microbes are activated by sunlight to release CO2 from warming permafrost. But the study also hints how natural processes might interrupt or slow this down. I wonder if we could also inhibit these particular microbes. https://www.nature.com/articles/s41467-017-00759-2 <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_s41467-2D017-2D00759-2D2&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=llMkAj_-4USXhO1tjCJa2n3LEg5ADgcT7HLYb5X_7c0&s=QacywPiGcwzMbq0GX5sL3Y6HImyP6aVBLgTMol2JwV0&e=> Summary/interview: https://www.sciencedaily.com/releases/2017/10/171004163800.htm <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.sciencedaily.com_releases_2017_10_171004163800.htm&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=llMkAj_-4USXhO1tjCJa2n3LEg5ADgcT7HLYb5X_7c0&s=njHAqq5oNkSOAgu3pPsEA1TZLJvZ5HUozwHgHb-fA7Y&e=> -- 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 geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering <https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_group_geoengineering&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=llMkAj_-4USXhO1tjCJa2n3LEg5ADgcT7HLYb5X_7c0&s=a4U9ojlVMofnLNqoKG1Ci64jJy90DHE_iLkCzM83fc0&e=> . For more options, visit https://groups.google.com/d/optout <https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=llMkAj_-4USXhO1tjCJa2n3LEg5ADgcT7HLYb5X_7c0&s=8zn2hHXgD_UvKng6ZIFxzZnk-VM44532iU77oCBZyRs&e=> . -- 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 geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout. -- 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 geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
