HR: 12:05h
AN: OS12A-08    [Abstracts]
TI: Gas Hydrates as a CH₄ Source and a CO₂ Sink: New Approaches Based on Fundamental Research
AU: * Schicks, J M
EM: schick@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Spangenberg, E
EM: erik@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Erzinger, J
EM: erz@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AB: The huge amount of methane, stored in the gas hydrate reservoirs of the world suggests that natural gas hydrates may be used in the future as a source of energy. A first production test was performed during the Mallik 2002 Gas Hydrate Production Research Well Program, showing that the thermal stimulation of natural gas hydrates successfully results in methane production (Dallimore et al. 2005). However, regarding the energy balance, the most efficient method for methane production from hydrates still needs to be developed. From another point of view, the sequestration of CO₂ in form of gas hydrates in (marine) sediments is an interesting idea. A combination of methane production from natural gas hydrates on the one hand and CO₂ - sequestration on the other hand seems to be an obvious and ideal solution. Different studies on possible methods - e.g. the exchange of CH₄ with CO₂ in gas hydrates (Lee et al, 2003, Graue and Kvamme, 2006) - have been published recently and demonstrated that this could be a possible way, in principle. Our own investigations on the exchange of CH₄ with gaseous CO₂ showed that this reaction is much too slow and inefficient to be a reasonable approach. The exchange of only 20 percent CH₄ with CO₂ could be detected in stable structure I hydrate crystals after 120 hours. In addition, multicomponent hydrates containing higher hydrocarbons beside methane tend to be more stable than pure methane hydrates (Schicks et al, 2006). Therefore, the application of an additional and controlled method for CH₄ -hydrate destabilization seems to be necessary and might lead to an efficient release of CH₄ from and CO₂ inclusion into hydrates. In any case, the question of process optimization still remains. In this contribution the chances and challenges of a combination of these two processes based on experimental data will be examined. Different kinds of experiments have been performed on natural marine and permafrost gas hydrates and synthesized clathrate hydrates:

• Differential scanning calorimetric measurements for the determination of the specific enthalpy of dissociation,
• determination of stability fields for pure and multicomponent systems,
• CH₄ - CO₂ -exchange reaction in clathrate hydrates and
• CO₂ -hydrate formation in sediments under different pressure and temperature conditions were studied. Based on these fundamental data, new concepts for methane production and combined CO₂ - sequestration will be presented and discussed. Reference: S.R. Dallimore, T.S. Collet (Eds.), 2005. Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program, Mackenzie Delta, Northwest Territories, Canada, Geological Survey of Canada, WO H. Lee, Y. Seo, Y.-T. Seo, I.L. Moudrakovski, J.A. Ripmeester, 2003. Angewandte Chemie International Edition, 42, 5049-5051 A. Graue, B. Kvamme, 2006. Conference Paper presented at the Offshore Technology Conference in Houston, Texas, U.S.A., 1-4 May 2006 J.M. Schicks, R. Naumann, J. Erzinger, K.C. Hester, Caroly A. Koh, E.D. Sloan, 2006. Journal of Physical Chemistry, 110, 11468-11474
  DE: 1012 Reactions and phase equilibria (3612, 8412)
  DE: 4806 Carbon cycling (0428)
  SC: Ocean Sciences [OS]
  MN: 2007 Fall Meeting