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The venting of anthropogenic CO₂ emissions into the atmosphere at increasing rates is probably influencing global warming and climate change. The Tangguh LNG development project in Papua, Indonesia will produce significant volumes of CO₂, which might be vented into the atmosphere. The LNG process will necessitate the separation of CO₂, estimated at 2.4 trillion cubic feet (TCF sc), from the natural gas reserves prior to liquefaction and shipping. This study screens and assesses the possible alternatives to atmospheric venting, and recommends subsurface CO₂ injection and sequestration/storage in saline aquifers. The study identifies specific subsurface locations for several Environmentally-Sustainable Sites for CO₂ Injection (ESSCI) in Bintuni Basin, where the Tangguh production fields are located. Alternatives to atmospheric venting of the estimated CO₂ volume at Tangguh include both non-geologic and geologic disposal options. Non-geologic options such as biosphere sinks (enhanced forest or agricultural growth), deep-ocean sinks (subsea dispersal), and direct commercial usage (e.g. use in beverage or fertilizer production, fire-retardant manufacturing) are impractical and of questionable impact in remote Papua, Indonesia. Several subsurface geological disposal options were investigated, but the most viable geologic disposal option for Tangguh CO₂ is injection into the downdip aquifer leg of the Roabiba Sandstone Formation hydrocarbon reservoir. Injected CO₂, at supercritical phase, is expected to migrate updip into the sealed structural traps at Vorwata or Wiriagar Deep, as the natural gas reserves are produced. A probabilistic ranking of data quality and quantity for five potential ESSCI reservoirs determined that the Middle Jurassic Roabiba Sandstone Formation has the highest likelihood of viable ESSCI sequestration/storage. A probabilistic ranking of data quality and quantity for eight ESSCI structural traps within the western flank of Bintuni Basin, determined that Vorwata, followed by Wiriagar Deep, are the most viable ESSCI structural traps at the Middle Jurassic reservoir level. Five potential ESSCI seals were evaluated and it was determined the best seal potential occurs in the Pre-Ayot Shales, directly overlying the Middle Jurassic reservoir at Vorwata. This unit is capable of holding a 3300 to 4660 foot (1006 to 1420 meter) CO₂_column. Seal integrity of the Pre-Ayot is very good because it is a relatively homogeneous deep-water shale that is composed primarily of ductile illite and kaolinite clays with a minor quartz and feldspar content. Sequence stratigraphy analysis suggests that the zone extends over the entire Vorwata three-way dip closure, with thickness between 17 feet (5 m) and 233 (71 m) feet. The maximum effective storage capacity of the Middle Jurassic reservoirs for each structure was calculated, taking into account irreducible water, trapped water, and trapped residual gas pore volumes. The Vorwata structure is capable of storing 19.3 TCFsc supercritical CO₂ at reservoir temperature and pressure. The Wiriagar Deep structure has potential storage capacity of 3.5 TCFsc, and Ubadari 2.8 TCFsc, at their respective reservoir temperatures and pressures. A ‘Rating Product Ranking’ was developed to quantify the results of the quality and quantity of four factors: Reservoir Data, Structure Data, Seal Data, and Storage Ratio. Each structure, and the respective top and lateral seal overlying the Middle Jurassic reservoirs, was evaluated. The net result was that Vorwata rated a 0.88 on a scale of zero to one, where 1.0 represents 100% confidence in ESSCI potential. Ubadari and Wiriagar Deep scored, respectively, 0.52 and a 0.45. Finally, the structures were evaluated for relative proximity to the proposed CO₂_source (i.e. the LNG plant location). With a weighted distance factor calculated with the Rating product for each potential injection site, Vorwata rated 0.88 on a scale of zero to one, Wiriagar scored 0.24, and Ubadari scored only 0.09. The Middle Jurassic ‘Roabiba Sandstone Formation reservoir’ at the Vorwata structure has the greatest potential as an ESSCI storage site. The Middle Jurassic ‘Aalenian Sandstone Formation reservoir’ at the Wiriagar Deep is the second-best potential ESSCI storage site. The subsurface ESSCI injection location proposed for the ‘Roabiba Sandstone Formation’ aquifer, 10 km southeast and down-dip from the known gas-water contact (GWC), is on the southeast Vorwata plunging anticlinal nose. An alternate potential ESSCI injection location proposed for the ‘Roabiba Sandstone Formation’ aquifer is 6 km south of and down-dip from the known gaswater contact (GWC) on Vorwata structure southern flank. A key issue was to determine the possible risk of fault re-activation from CO₂_ injection. NE-SW striking vertical faults have the highest risk of re-activation requiring an increase of over ~1460 psi (103 kg/cc) over hydrostatic at 14,000 ft TVDss (4267 m), for slippage to occur. The closest fault with a high risk of re- activation is 5 km northwest of the recommended ESSCI site location. Supercritical CO₂_ pressure is not expected to exceed the estimated pressure determined to cause fault re-activation. A 3D geological model of the Mesozoic interval was constructed over a large area of western Bintuni Basin. The model was constructed so as to preserve as much geological heterogeneity as possible yet still have a manageable number of active cells. Faults were incorporated into the model as strike-slip vertical fault surfaces (or indexed fault polygons) as a separate attribute. The geo-cellular model was built suitable for importation into a reservoir simulator (VIP), and a 25-year simulation run for natural gas production from the Vorwata Middle Jurassic reservoir, with concurrent CO₂ injection downdip into the Vorwata Middle Jurassic aquifer at the primary recommended ESSCI site location. The simulation verified the recommended location with the CO₂ slowly migrating into the Vorwata structural trap within the Middle Jurassic reservoir, and not compromising the hydrocarbon reserves or production. It is recommended that additional data be acquired such as conventional core, formation water samples, and specific logs such as dipole-sonic, multi-chambered dynamic formation testers (MDT), and mechanical rotary sidewall coring tools (MSCT). Lastly, several CO₂ monitoring methods and techniques are recommended for Tangguh to monitor CO₂ migration, pressures, and potential leakages. One such method is a vertical monitoring well at the recommended injection site. Other monitoring techniques include smart well completions, detection monitors at production wells with tracers injected prior to CO₂ injection. In addition, crosswell seismic surveys, electromagnetic methods, and electrical-resistance tomography techniques are suggested during the injection phase. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1174414 / Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2005

Globally, the forestry sector is the second largest contributor of greenhouse gases, and sustainable forest management is a major target of international environmental policy. However, there is the assumption underlying many policy recommendations that an increase in above-ground carbon stocks correspond to long term increases in ecosystem carbon stocks, the majority of which is stored in soils. We analyzed soil carbon and nitrogen dynamics in forest soils that had undergone twenty years of organic inputs manipulations as part of the Detritus Input and Removal Treatment (DIRT) network. There was no statistically significant effect of the rate of litter or root inputs on the carbon or nitrogen in bulk soil, on respiration rates of soil in laboratory incubations, on the non-hydrolyzed fraction of soil organic matter, or on any organic matter associated with any density. However, there is evidence for positive priming due to increased litter inputs; doubling the rate of litter inputs decreased C and N contents of bulk soil and decreased respiration rates of soil. Furthermore, there is evidence that roots influence soil organic matter dynamics more strongly than above-ground inputs. Both of these results trends match data from other DIRT sites, and are supported by the literature. / Graduation date: 2012

Geological carbon sequestration, as a method of atmospheric greenhouse gas reduction, is at the technological forefront of the climate change movement. During sequestration, carbon dioxide (CO���) gas effluent is captured from coal fired power plants and is injected into a storage saline aquifer or depleted oil reservoir. In an effort to fully understand and optimize CO��� trapping efficiency, the capillary trapping mechanisms that immobilize subsurface CO��� were analyzed at the pore-scale. Pairs of proxy fluids representing the range of in situ supercritical CO��� and brine conditions were used during experimentation. The two fluids (identified as wetting and non-wetting) were imbibed and drained from a flow cell apparatus containing a sintered glass bead column. Experimental and fluid parameters, such as interfacial tension, fluid viscosities and flow rate, were altered to characterize their relative impact on capillary trapping. Computed x-ray microtomography (CMT) was used to identify immobilized CO��� (non-wetting fluid) volumes after imbibition and drainage events. CMT analyzed data suggests that capillary behavior in glass bead systems do not follow the same trends as in consolidated natural material systems. An analysis of the disconnected phases in both the initial and final flood events indicate that the final (residual) amount of trapped non-wetting phase has a strong linear dependence on the original amount of non-wetting phase (after primary imbibition), which corresponds to the amount of gas or oil present in the formation prior to CO��� injection. More importantly, the residual trapped gas was also observed to increase with increasing non-wetting fluid phase viscosity. This suggests that CO��� sequestration can be optimized in two ways: through characterization of the trapped fluid present in the formation prior to injection and through alterations to the viscosity of supercritical CO2. / Graduation date: 2013

Wälder haben im Bezug zum Klimawandel mehrere Rollen: Sie sind Kohlenstoffspeicher, -senken, sowie Lieferanten von Holz als Rohstoff für die Kohlenstoffspeicher in Produkten und für Substitution fossiler Energieträger. Unter Klimaschutzgesichtspunkten ist es wünschenswert, die Kohlenstoffbindung im Gesamtsystem aus Senken, Speichern und Substitution zu maximieren und zu entscheiden, welche Maßnahme an welchem Ort und unter welchen Rahmenbedingungen den größten positiven Effekt auf die CO2-Bilanz hat. Um die Speicherung in den verschiedenen Kompartimenten erfassen zu können müssen geeignete Inventurverfahren zur Verfügung stehen. Die IPCC – GPG benennen die Speicher und geben zum Teil Anforderungen an die zu erreichende Inventurgenauigkeit. Aus der klassischen Forsteinrichtung stehen genügend Methoden zur Verfügung, um das oberirdische Volumen sehr genau zu erheben. Um den Anforderungen an ein umfassendes Kohlenstoffmonitoring genügen zu können, müssen diese Verfahren in den Bereichen Erfassung von Störungsfolgen, Totholzdynamik, Boden und der Berechnung von Gesamt-Kohlenstoffvorräten aus dem Holzvolumen ergänzt werden. Zusätzlich bietet sich an, Bewirtschaftungsmaßnahmen entsprechend zu erfassen, um ihre Auswirkung auf die Kohlenstoffdynamik ebenfalls feststellen zu können. Dies ist für die Berichterstattung zwischen Inventuren sowie für die Herausrechnung von nicht-menschenverursachter erhöhter Kohlenstoffspeicherung („factoring out“ im Sinne des KP) wünschenswert. Wenn Bewirtschaftungsmaßnahmen unterschieden werden können und ihre Auswirkungen auf C-Vorräte bestimmbar sind, ist eine Verifizierung erhöhter Speicherung auch z. B. für Projekte nach Art. 3.4 des KP durchführbar. Diese Arbeiten stecken jedoch noch in der Anfangsphase. Im Rahmen dieser Arbeit wurde die erste verfügbare qualitative Übersicht zu dieser Thematik erstellt. Die Optimierung der Wald-Holz-Option wird durch die im Kyoto-Protokoll (und den zugehörigen Folgeabkommen) vereinbarten Regelungen erschwert, da einerseits zwischen Wald und Produkten eine Trennung besteht und andererseits die Maßnahmenverantwortlichem im Wald nicht direkt durch das KP angesprochen werden. Eingeschlagenes Holz wird im Wald als Emission betrachtet und dem entsprechenden Sektor zugerechnet, was jedoch keine Auswirkungen auf den Forstbetrieb hat. Dieser profitiert im Gegenteil derzeit von der durch die – auch von KP Regelungen beeinflussten – Holzpreise und erhöht die Nutzungen, was zu Vorratsabsenkungen im Wald führt. Ob diese Absenkungen durch die Substitutionseffekte des geernteten Holzes kompensiert werden ist derzeit noch nicht geklärt. Um die Trennung zwischen Wald und Produktpool aufzuweichen bietet es sich an, die Waldbesitzer am Emissionsrechtehandel teilhaben zu lassen, damit nicht nur die Ernte sondern auch der Ernteverzicht finanziell bewertbar sind. Sozio-ökonomische Szenarien zur künftigen Entwicklung der Landwirtschaft zeigen große Flächenpotentiale, die für die Nahrungs- und Futtermittelproduktion nicht mehr benötigt werden oder nicht mehr rentabel sein werden. Eine mögliche Nutzung in Zukunft sind Energieholzplantagen. Informationen zu möglichen Erträgen sind zur Zeit noch unzureichend und Analysen zur Nachhaltigkeit dieser Erträge unter Klimawandel sind nicht vorhanden. In dieser Arbeit wurde mit dem ökophysiologischen Waldwachstumsmodell 4C an Beispielsstandorten in Brandenburg das Wachstum von Energieholzplantagen unter derzeitigem Klima und unter verschiedenen regionalisierten Klimawandelszenarien bis 2055 simuliert. Ertragspotentiale liegen derzeit auf der Mehrzahl der Standorte im positiven Bereich, auf einigen Standorten ist jedoch nur begrenzt mit positiven Deckungsbeiträgen zu rechnen. Bis 2055 ist in allen Szenarien mit einem leichten Rückgang der Erträge und einer deutlicheren Verringerung der Grundwasserneubildung unter Energieholzplantagen zu rechnen. Die Unterschiede zwischen Standorten sind jedoch derzeit und unter zukünftig möglichem Klima stärker als klimabedingte Änderungen. Bei der großflächigen Anlage von Energieholzplantagen können negative Auswirkungen auf die Biodiversität und andere Naturschutzbelange eintreten. Eine diese Effekte abmildernde Flächengestaltung, die trotzdem Erträge auf dem Niveau heutiger Vollerwerbslandwirtschaft erreicht, ist möglich. Insgesamt lässt sich für die Optimierung der Wald-Holz-Option feststellen, dass eine Nicht-Nutzung bestehender Waldflächen unter Klimaschutzgesichtspunkten negativ ist. Der Substitutionseffekt geernteten Holzes beträgt zusätzliche ca. 70 Prozent Kohlenstoff, die in dieser Form in nicht bewirtschafteten mitteleuropäischen Wäldern nicht zusätzlich gespeichert werden. Es ist davon auszugehen, dass sich durch die Berücksichtigung von Substitutionseffekten andere – wahrscheinlich kürzere – als die heute üblichen Produktionszeiten ergeben. Auf bisher waldfreien Flächen ist die Anlage von Energieholzplantagen positiver zu werten als eine normale Aufforstung. / Forests are important for climate protection: They sequester and store carbon, and provide timber for wood products and fossil fuel substitution. These functions interact in a complex way. From a climate protection point of view it is desirable to optimize these interactions, i.e. to maximize the amount of carbon stored in the whole system (called „forest-timber-option“) and to analyse what impact a management decision at the local level has with regard to the amount of carbon in the atmosphere. Inventory methods to estimate the total amount of carbon in a forest are needed. Classical forest inventories assess above-ground tree volume. To estimate total car-bon in accordance with the requirements of the Kyoto-Protocol, these inventories need to be expanded with regard to the assessment of disturbances, dead wood de-composition, soil carbon, and the estimation of carbon from volume. Methods in-vented here can also be used to assess local-level management activities, or to “fac-tor out” non-human-induced changes in carbon pools. The optimization of the „forest-timber-option“ is restricted due to regulations of the Kyoto-Protocol, because forest-related measures are accounted for under other sec-tors than wood and timber use. Harvested timber is estimated as an “emission” from the forest, and forest owners have no benefit from the use of wood for industrial pur-poses. Here, an inclusion of forestry in emission trading schemes can be advanta-geous. Alternative ways to produce wood are short-rotation coppice plantations on agricul-tural soils. Information about growth and yield potentials are scarce for the regions where land availability is high. Aspen (P. tremula, P. tremuloides) was parameterized in an eco-physiological forest growth model (“4C”) to assess these potentials on sites in Eastern Germany under current and under changing climatic conditions. The re-sults indicate that growth potentials are more sensitive to soil quality than to climatic conditions. Potential yields allow for incomes comparable to standard agriculture, but biodiversity and groundwater recharge may be negatively affected by large-scale plantations. An optimization of the „forest-timber-option“ requests the use of timber from forests. Harvested timber substitutes additional 70 % of carbon from fossil fuels. Forests un-der total protection do store more carbon than managed forest, but not equivalent to the substitution effects. Total protection of forests is thus no viable means for climate protection under Central European conditions.

In order to fully understand the magnitude of the benefits that forests provide, it is crucial to understand the full suite of ecosystem services that they offer. A southern Appalachian red spruce-Fraser fir forest was intensively analyzed using a variety of methodologies to determine the nature and quantity of some of these services. Many hypotheses exist regarding the future of these spruce-fir forests, which were heavily disturbed by the non-native balsam wooly adelgid during the 1980s. Direct measurements over the course of a decade assessed these hypotheses and indicate that this forest is recovering structure and function. The forest is accruing overstory biomass, with vegetation composition on a trajectory towards historic conditions. By using a total forest inventory of all vegetation from overstory trees to understory mosses, rates of productivity and nutrient cycling were determined. Productivity of this forest at low elevations has returned to pre-adelgid levels, while at high elevations productivity is approaching these levels. In the absence of an intact overstory, forest understory vegetation can compensate by disproportionately cycling and retaining nutrients such as nitrogen that would otherwise leach offsite. The understory of this forest provides an important service in nutrient cycling. Our ability to actively manage forests in order to manipulate levels and rates of carbon sequestration was assessed using stand data and the Forest Vegetation Simulator Growth and Yield Model. Silvicultural intervention proved effective at sequestering additional carbon over a no action alternative by the end of our simulation period. This forest provides a variety of ecosystem services and has retained its ability to recover their function after catastrophic disturbance.

This work examines the impact of a viscosity force parameter, fluid velocity, and a capillary force parameter, interfacial tension, on the saturation, morphology, and topology of NW fluid in Bentheimer sandstone after primary imbibition, drainage, and secondary imbibition. Brine and air (used as a proxy for supercritical CO₂) flow experiments were performed on 6 mm diameter Bentheimer cores and were quantified via imaging with x-ray computed microtomography (x-ray CMT), which allows for three dimensional, non-destructive, pore-scale analysis of the amount and distribution of NW phase fluid within the sandstone cores. It was found that trapped NW phase saturation decreases with increases in capillary number, average blob size decreases with increases in capillary number, and the number of NW blobs increases with increases in capillary number. In addition, it was found that NW phase trapping is dependent on initial NW phase connectivity within the porous medium; with more negative values of initial NW phase Euler number resulting in less trapping. We suggest that the Euler number-saturation and the capillary number-saturation relationships for a given medium should be taken into consideration when designing a CO₂ sequestration scenario. / Graduation date: 2013

Intentional amendment of soil with charcoal (called biochar) is a promising new approach to sequester atmospheric carbon dioxide and increase soil fertility. However, the environmental properties of biochars can vary with production conditions, making it challenging to engineer biochars that are simultaneously optimized for carbon sequestration, nutrient storage, and water-holding capacity. For this reason, I have undertaken a systematic study to (a) determine the pyrolysis conditions that lead to biochars with desired chemical and physical properties, and (b) find how these properties affect the water-holding capacity and nutrient adsorption in biochar-soil mixtures. First, a library of biochars was produced in a custom-built pyrolysis reactor under precisely controlled conditions. The chemical and physical structures of the produced biochars were characterized with various analytical techniques including 13C NMR, XPS, EA and BET pore surface analysis. My results suggest that the chemical composition and pore structure of biochars are determined not just by the maximum heat treatment temperature, but also by several other factors that include the pyrolysis heating rate, treatment time at the maximum temperature and particle size. I also tested a new approach that combines thermogravimetric reactivity measurements, diffusion-reaction theory and structural models to achieve a better characterization of the complicated multi-scale pore structure of biochars. The structural models treat biochars as porous solids having micro- and macropores of different shapes and exhibiting widely ranging pore-size distributions. Simulations results are then compared to experimental data to identify the presence of ordered or random pore networks and test their size distributions and connectivity. I then developed a multi-solid one-dimensional model that can use experimentally determined biochar properties to predict their field performance in beds packed with soil/biochar mixtures. The model used a system of coupled partial differential equations to describe the dynamic adsorption/elution of ammonium nitrate, a model fertilizer, in columns packed with biochar/soil mixtures and perfused with aqueous solutions of the fertilizer. The PDE system was solved using orthogonal collocation on finite elements. My chromatographic model accounted for all the important processes occurring in this system, including external mass transfer between the fluid phase and the solid particles, as well as intraparticle diffusion and adsorption of the solute on the pore surface area of the sorbents. To our knowledge, this is the first chromatographic model that accounted explicitly for the presence of two solid phases with widely different pore structures and adsorption capacities. A systematic parametric study was carried out to determine the importance of each system parameter. The adsorption equilibrium parameters and the intraparticle effective diffusivity of ammonium had the most significant effect on environmental performance. To complete the theoretical analysis, I also developed a model to describe the saturation and drainage of water from the packed column. The model accounted for all the important processes occurring in this system: (a) water exchange between the interstitial pore region and two different smaller pore regions and (b) water flow inside the larger pore region and the two different smaller pore regions. The transient mass balances led to a system of partial differential equations that was solved using block centered finite difference.

Understanding the physics of multiphase plumes and their simulation through numerical modeling has been an important area of research in recent times in the area of environmental fluid mechanics. The two renowned numerical modeling types that are commonly used by researchers today to simulate multiphase plumes in nature are the mixed-fluid and the two-fluid integral models. In the present study, a detailed review was performed to study and analyze the two modeling approaches for the case of a double plume (upward moving inner plume with downward moving annular outer plume) with the objective of ascertaining which of these models represent the prototype physics in the integral plume model equations with a higher degree of completeness and accuracy. A graphical user interface was designed to facilitate running the models. By comparison to laboratory scale experimental data and through sensitivity analyses, a rigorous effort was made to determine the most appropriate choice of initial conditions needed at the start of the model computation and at the peeling locations and to obtain the most consistent values of the different model parameters that are necessary for calibration of the two models. Consequently, with these selected sets of initial conditions and model parameters, the models were run and their outputs compared against each other for three different case studies with ambient conditions typical of real environmental data. The dispersed phases considered were air bubbles in two cases and liquid CO2 droplets for the third case, with water as the continuous phase in all cases. The entrainment coefficient was found to be the most important parameter that affected the model results. In all the three case studies conducted, the mixed-fluid model was found to predict about 30% higher values for the peel heights and the DMPR (Depth of Maximum Plume Rise) than the two-fluid model.

Mineralization has the potential to capture CO₂. In nature, mineralization is the chemical weathering of alkaline-earth minerals in which stable carbonate minerals are formed, which leads to the removal of CO₂ from the atmosphere. The adsorptive carbonation reaction of olivine ((Mg,Fe)₂SiO₄)), consisting mainly of pure magnesium silicate (Mg₂SiO₄), a main constituent of the Earth’s crust, was carried out to estimate its potential application to the separation of CO₂ in the presence of water vapor in combustion plumes. Based on the thermodynamics for a basis of the reaction mechanism, the olivine carbonation reaction is thermodynamically favorable. Water vapor was found to play an important role in improving the carbonation rate, and experimental results revealed that carbon dioxide carbon dioxide can bind into olivine minerals to form highly stable surface carbonates. The reaction activity of olivine and pure Mg₂SiO₄ in the presence/absence of water vapor was carried out by varying the temperature, reactant concentrations, and space time. Based on changes in CO₂ concentration with time, the reaction kinetic model of pure Mg₂SiO₄carbonation was developed. The reaction order was found to be approximately 1 for CO₂. The activation energy derived for the Arrhenius equation of Mg₂SiO₄-based carbonation is 76.2 ± 4.8 kJ/mol based on the changes in the reaction rates with temperature in the range of 150-200°C. To investigate the molecular reaction mechanism of CO₂ adsorption on the metal oxide surface, forming carbonates, we performed the quantum mechanical calculation of CO₂ adsorption on a CaO (100) surface. It shows that CO₂ molecules strongly react with the CaO surface due to its high reactivity and high basicity. Consequently, this study will basically lay the groundwork for the chemical mechanism of mineral carbonation of olivine with carbon dioxide in the presence of water vapor and as provide relevant information for the practical application of CO₂ sequestration by stable adsorption on mineral silicates.