@article{MarUngerWalderdorffetal.2022,
  author    = {Mar, Kathleen A. and Unger, Charlotte and Walderdorff, Ludmila and Butler, Tim},
  title     = {Beyond CO2 equivalence},
  series = {Environmental science \& policy},
  volume    = {134},
  journal   = {Environmental science \& policy},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1462-9011},
  doi       = {10.1016/j.envsci.2022.03.027},
  pages     = {127 -- 136},
  year      = {2022},
  abstract  = {In this article we review the physical and chemical properties of methane (CH4) relevant to impacts on climate, ecosystems, and air pollution, and examine the extent to which this is reflected in climate and air pollution governance. Although CH4 is governed under the UNFCCC climate regime, its treatment there is limited to the ways in which it acts as a "CO2 equivalent" climate forcer on a 100-year time frame. The UNFCCC framework neglects the impacts that CH4 has on near-term climate, as well its impacts on human health and ecosystems, which are primarily mediated by methane's role as a precursor to tropospheric ozone. Frameworks for air quality governance generally address tropospheric ozone as a pollutant, but do not regulate CH4 itself. Methane's climate and air quality impacts, together with its alarming rise in atmospheric concentrations in recent years, make it clear that mitigation of CH4 emissions needs to be accelerated globally. We examine challenges and opportunities for further progress on CH4 mitigation within the international governance landscapes for climate change and air pollution.},
  language  = {en}
}
@misc{MaLiKuehnetal.2018,
  author    = {Ma, Jianli and Li, Qi and K{\"u}hn, Michael and Nakaten, Natalie Christine},
  title     = {Power-to-gas based subsurface energy storage},
  series = {Renewable and Sustainable Energy Reviews},
  volume    = {97},
  journal   = {Renewable and Sustainable Energy Reviews},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1364-0321},
  doi       = {10.1016/j.rser.2018.08.056},
  pages     = {478 -- 496},
  year      = {2018},
  abstract  = {The Renewable energy power generation capacity has been rapidly increasing in China recently. Meanwhile, the contradiction between power supply and demand is becoming increasingly more prominent due to the intermittence of renewable energies. On the other hand, on the mitigation of carbon dioxide (CO2) emissions in China needs immediate attention. Power-to-Gas (PtG), a chemical energy storage technology, can convert surplus electricity into combustible gases. Subsurface energy storage can meet the requirements of long term storage with its large capacity. This paper provides a discussion of the entire PtG energy storage technology process and the current research progress. Based on the comparative study of different geological storage schemes for synthetic methane, their respective research progress and limitations are noted. In addition, a full investigation of the distribution and implementation of global PtG and CO2 capture and storage (CCS) demonstration projects is performed. Subsequently, the opportunities and challenges of the development of this technology in China are discussed based on techno-economic and ecological effects analysis. While PtG is expected to be a revolutionary technology that will replace traditional power systems, the main issues of site selection, energy efficiency and the economy still need to be adequately addressed. Additionally, based on the comprehensive discussion of the results of the analysis, power-to-gas and subsurface energy storage implementation strategies, as well as outlook in China are presented.},
  language  = {en}
}
@article{HeslopAnthonyGrosseetal.2019,
  author    = {Heslop, J. K. and Anthony, K. M. Walter and Grosse, Guido and Liebner, Susanne and Winkel, Matthias},
  title     = {Century-scale time since permafrost thaw affects temperature sensitivity of net methane production in thermokarst-lake and talik sediments},
  series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man},
  volume    = {691},
  journal   = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0048-9697},
  doi       = {10.1016/j.scitotenv.2019.06.402},
  pages     = {124 -- 134},
  year      = {2019},
  abstract  = {Permafrost thaw subjects previously frozen soil organic carbon (SOC) to microbial degradation to the greenhouse gases carbon dioxide (CO2) and methane (CH4). Emission of these gases constitutes a positive feedback to climate warming. Among numerous uncertainties in estimating the strength of this permafrost carbon feedback (PCF), two are: (i) how mineralization of permafrost SOC thawed in saturated anaerobic conditions responds to changes in temperature and (ii) how microbial communities and temperature sensitivities change over time since thaw. To address these uncertainties, we utilized a thermokarst-lake sediment core as a natural chronosequence where SOC thawed and incubated in situ under saturated anaerobic conditions for up to 400 years following permafrost thaw. Initial microbial communities were characterized, and sediments were anaerobically incubated in the lab at four temperatures (0 °C, 3 °C, 10 °C, and 25 °C) bracketing those observed in the lake's talik. Net CH4 production in freshly-thawed sediments near the downward-expanding thaw boundary at the base of the talik were most sensitive to warming at the lower incubation temperatures (0 °C to 3 °C), while the overlying sediments which had been thawed for centuries had initial low abundant methanogenic communities (< 0.02\%) and did not experience statistically significant increases in net CH4 production potentials until higher incubation temperatures (10 °C to 25 °C). We propose these observed differences in temperature sensitivities are due to differences in SOM quality and functional microbial community composition that evolve over time; however further research is necessary to better constrain the roles of these factors in determining temperature controls on anaerobic C mineralization.},
  language  = {en}
}
@article{SchirmackBoehmBraueretal.2014,
  author    = {Schirmack, Janosch and Boehm, Michael and Brauer, Chris and L{\"o}hmannsr{\"o}ben, Hans-Gerd and de Vera, Jean-Pierre Paul and Moehlmann, Diedrich and Wagner, Dirk},
  title     = {Laser spectroscopic real time measurements of methanogenic activity under simulated Martian subsurface analog conditions},
  series = {Planetary and space science},
  volume    = {98},
  journal   = {Planetary and space science},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0032-0633},
  doi       = {10.1016/j.pss.2013.08.019},
  pages     = {198 -- 204},
  year      = {2014},
  abstract  = {On Earth, chemolithoautothrophic and anaerobic microorganisms such as methanogenic archaea are regarded as model organisms for possible subsurface life on Mars. For this reason, the methanogenic strain Methanosarcina soligelidi (formerly called Methanosarcina spec. SMA-21), isolated from permafrost-affected soil in northeast Siberia, has been tested under Martian thermo-physical conditions. In previous studies under simulated Martian conditions, high survival rates of these microorganisms were observed. In our study we present a method to measure methane production as a first attempt to study metabolic activity of methanogenic archaea during simulated conditions approaching conditions of Mars-like environments. To determine methanogenic activity, a measurement technique which is capable to measure the produced methane concentration with high precision and with high temporal resolution is needed. Although there are several methods to detect methane, only a few fulfill all the needed requirements to work within simulated extraterrestrial environments. We have chosen laser spectroscopy, which is a non-destructive technique that measures the methane concentration without sample taking and also can be run continuously. In our simulation, we detected methane production at temperatures down to -5 degrees C, which would be found on Mars either temporarily in the shallow subsurface or continually in the deep subsurface. The pressure of 50 kPa which we used in our experiments, corresponds to the expected pressure in the Martian near subsurface. Our new device proved to be fully functional and the results indicate that the possible existence of methanogenic archaea in Martian subsurface habitats cannot be ruled out. (C) 2013 Published by Elsevier Ltd.},
  language  = {en}
}
@article{BalckeHahnOswald2011,
  author    = {Balcke, Gerd U. and Hahn, M. and Oswald, Sascha Eric},
  title     = {Nitrogen as an indicator of mass transfer during in-situ gas sparging},
  series = {Journal of contaminant hydrology},
  volume    = {126},
  journal   = {Journal of contaminant hydrology},
  number    = {1-2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0169-7722},
  doi       = {10.1016/j.jconhyd.2011.05.005},
  pages     = {8 -- 18},
  year      = {2011},
  abstract  = {Aiming at the stimulation of intrinsic microbial activity, pulses of pure oxygen or pressurized air were recurrently injected into groundwater polluted with chlorobenzene. To achieve well-controlled conditions and intensive sampling, a large, vertical underground tank was filled with the local unconfined sandy aquifer material. In the course of two individual gas injections, one using pure oxygen and one using pressurized air, the mass transfer of individual gas species between trapped gas phase and groundwater was studied. Field data on the dissolved gas composition in the groundwater were combined with a kinetic model on gas dissolution and transport in porous media. Phase mass transfer of individual gas components caused a temporary enrichment of nitrogen, and to a lower degree of methane, in trapped gas leading to the formation of excess dissolved nitrogen levels downgradient from the dissolving gas phase. By applying a novel gas sampling method for dissolved gases in groundwater it was shown that dissolved nitrogen can be used as a partitioning tracer to indicate complete gas dissolution in porous media.},
  language  = {en}
}