Polymers rich in primary amine groups are proposed to be effective adsorbents for the reversible adsorption of CO2 from moderately dilute gas streams (10% CO2) and ultra-dilute gas streams (e.g. ambient air, 400 ppm CO2), with their performance under ultra-dilute conditions being competitive with or exceeding the state-of-the-art adsorbents based on supported poly(ethyleneimine) (PEI). The CO2 adsorption capacity (mmol CO2/g sorbent) and amine efficiency (mmol CO2/mmol amine) of linear poly(allylamine) (PAA), cross-linked poly(allylamine) prepared by post-polymerization crosslinking with epichlorohydrin (PAAEPI), and branched poly(allylamine) prepared by branching of poly(allylamine) with divinylbenzene (PAADVB) are presented here and compared with state-of-the-art adsorbents based on supported PEI, specifically branched and linear, low molecular weight PEI. Silica mesocellular foam, MCF, serves as the support material for impregnation of the amine polymers. In general, branched polymers are found to yield more effective adsorbents materials. Overall, the results of this work show that linear PAA, cross-linked PAAEPI, and branched PAADVB are promising candidates for solid adsorbents with high capacity for CO2.

Compositional reservoir simulation studies were performed to investigate the effect of uncertain reservoir parameters, flood design variables, and economic factors on coupled CO₂ sequestration and EOR projects. Typical sandstone and carbonate reservoir properties were used to build generic reservoir models. A large number of simulations were needed to quantify the impact of all these factors and their corresponding uncertainties taking into account various combinations of the factors. The design of experiment method along with response surface methodology and Monte-Carlo simulations were utilized to maximize the information gained from each uncertainty analysis. The two objective functions were project profit in the form of $/bbl of oil produced and sequestered amount of CO₂ in the reservoir. The optimized values for all objective functions predicted by design of experiment and the response surface method were found to be close to the values obtained by the simulation study, but with only a small fraction of the computational time. After the statistical analysis of the simulation results, the most to least influential factors for maximizing both profit and amount of stored CO₂ are the produced gas oil ratio constraint, production and injection well types, and well spacing. For WAG injection scenarios, the Dykstra-Parsons coefficient and combinations of WAG ratio and slug size are important parameters. Also for a CO₂ flood, no significant reduction of profit occurred when only the storage of CO₂ was maximized. In terms of the economic parameters, it was demonstrated that the oil price dominates the CO₂ EOR and storage. This study showed that sandstone reservoirs have higher probability of need for CO₂i ncentives. In addition, higher CO₂ credit is needed for WAG injection scenarios than continuous CO₂ injection. As the second part of this study, scaling groups for miscible CO₂ flooding in a three-dimensional oil reservoir were derived using inspectional analysis with special emphasis on the equations related to phase behavior. Some of these scaling groups were used to develop a new MMP correlation. This correlation was compared with published correlations using a wide range of reservoir fluids and found to give more accurate predictions of the MMP. / text

Over the past couple of decades, there has been an increased interest in evaluating the environmental impacts of some turfgrass management practices. Two independent studies were conducted to examine different questions of turfgrass management impacts and sustainability. The first study examined the inputs and outputs of four different turfgrass home lawn systems. Two of these systems were designated as high maintenance and were composed of either a pure stand of Kentucky bluegrass (Poa pratensis L.) or tall fescue (Festuca arundinacea Schreb.). The other two systems were designated as low maintenance and were composed of either a pure stand of zoyisagrass (Zoysia japonica Steud.) or a mixed species endemic polystand. Soil samples were taken yearly from each plot and analyzed to determine total carbon content. Results from this study indicated carbon and nitrogen pools were not significantly different between the four systems but depth of sampling was significant. For the second study, various formulated surfactants were examined to determine if they could enhance the fungicidal activity of a protein washed and concentrated from tobacco leaves (Nicotiana tabacum L.) that has been shown to be effective in combating foliar-infecting turfgrass diseases in previous studies. Since previous studies indicated the protein was most effective at high concentrations when applied every seven days, it was hypothesized a surfactant may allow the protein to perform as well for a longer period of time or at lower concentrations. The efficacy of the protein against a root infecting pathogen (Ophiosphaerella korrae) was also examined. Results from this study indicated a water based surfactant may allow solutions of the protein applied every 14 days to perform similarly to solutions of the protein alone applied every 7 days without a surfactant against Sclerotinia homoeocarpa F. T. Bennett. Also, the protein did appear to be somewhat effective in combating the root infecting pathogen tested in this study when applied on a schedule similar to current commercial fungicide recommendations.

Stacked storage systems are a viable carbon management operation, especially in regions with potential growth in CO₂ enhanced oil recovery (EOR) projects. Under a carbon constrained environment, the industrial Texas Gulf Coast is an ideal area for development of stacked storage operations, with a characteristically high CO₂ intensity and abundance of aging oil fields. The development of EOR along the Texas Gulf Coast is limited by CO₂ supply constraints. A stacked storage system is implemented with an EOR project to manage the temporal differences between the operation of a coal-fired power plant and EOR production. Currently, most EOR operations produce natural CO₂ from geologic formations. A switch to anthropogenic CO₂ sources would require an EOR operator to handle volumes of CO₂ beyond EOR usage. The use of CO₂ in an EOR operation is controlled and managed to maximize oil production, but increasing injection rates to handle the volume of CO₂ captured from a coal plant can decrease oil production efficiency. With stacked storage operations, a CO₂ storage reservoir is implemented with an EOR project to maintain injection capacity equivalent to a coal plant's emissions under a carbon constrained environment. By adding a CO₂ storage operation, revenue can still be generated from EOR production, but it is considerably less than just operating an EOR project. The challenge for an efficient stacked storage project is to optimize oil production and maximize profits, while minimizing the revenue reduction of pure carbon sequestration. There is an abundance of saline aquifers along the Texas Gulf Coast, including the Wilcox, Vicksburg, and Miocene formations. To make a stacked storage system more viable and reduce storage costs, maximizing injectivity is critical, as storage formations are evaluated on a cost-per-ton injected basis. This cost-per-ton injected criteria, also established as injection efficiency, incorporates reservoir injectivity and depth dependant drilling costs to determine the most effective storage formation to incorporate with an EOR project. With regionally adequate depth to maximize injectivity while maintaining reasonable drilling costs, the Vicksburg formation is typically the preferred storage reservoir in a stacked storage system along the Texas Gulf Coast. Of the eleven oil fields analyzed on a net present value basis, the Hastings field has the greatest potential for both EOR and stacked storage operations. / text

I present results from quantitative evaluation of the capability of hosting and trapping CO₂ of a carbonate brine reservoir from Dickman Field, Kansas. The analysis includes estimation of some reservoir parameters such as porosity and permeability of this formation using pre-stack seismic inversion followed by simulating flow of injected CO₂ using a simple injection technique. Liner et at (2009) carried out a feasibility study to seismically monitor CO₂ sequestration at Dickman Field. Their approach is based on examining changes of seismic amplitudes at different production time intervals to show the effects of injected gas within the host formation. They employ Gassmann's fluid substitution model to calculate the required parameters for the seismic amplitude estimation. In contrast, I employ pre-stack seismic inversion to successfully estimate some important reservoir parameters (P- impedance, S- impedance and density), which can be related to the changes in subsurface rocks due to injected gas. These are then used to estimate reservoir porosity using multi-attribute analysis. The estimated porosity falls within a reported range of 8-25%, with an average of 19%. The permeability is obtained from porosity assuming a simple mathematical relationship between porosity and permeability and classifying the rocks into different classes by using Winland R35 rock classification method. I finally perform flow simulation for a simple injection technique that involves direct injection of CO₂ gas into the target formation within a small region of Dickman Field. The simulator takes into account three trapping mechanisms: residual trapping, solubility trapping and mineral trapping. The flow simulation predicts unnoticeable changes in porosity and permeability values of the target formation. The injected gas is predicted to migrate upward quickly, while it migrates slowly in lateral directions. A large amount of gas is concentrated around the injection well bore. Thus my flow simulation results suggest low trapping capability of the original target formation unless a more advanced injection technique is employed. My results suggest further that a formation below our original target reservoir, with high and continuously distributed porosity, is perhaps a better candidate for CO₂ storage. / text

Woodlot and natural woodland systems in the semi-arid regions in Tanzania are believed to have a high potential to sequester carbon (C) in their biomass and the soil which may qualify for C credits under the current voluntary C market schemes like, the REDD program. However, our understanding of the processes influencing storage and dynamics of C in soils under semi-arid agroforestry systems such as these woodlot systems is limited. This study evaluated C pools in soil and tree biomass in woodlot species of Albizia lebbeck, Leucaena leucocephala, Melia azedarach, and Gmelina arborea; and in farmland and ngitili systems. Synchrotron-based C K-edge x-ray absorption near-edge structure (XANES) spectroscopy was also used to study the influence of these land use systems on the soil organic matter (SOM) chemistry to understand the mechanisms of soil C changes. Soil samples were collected to 1 m depth and subsamples for each land use system to 0.4 m depth were fractionated into macroaggregates (2000-250 μm), microaggregates (250-53 μm), and silt and clay-sized aggregates (<53 μm) to provide information of C dynamics and stabilization in various land uses. SOC was analyzed in whole and soil aggregates and biomass C was estimated using developed biomass models from the literatures. Aboveground biomass carbon in the woodlots from the Kahama district ranged from 11.76 Mg C ha-1 to 24.40 Mg C ha-1. Based on the age of woodlots and the rate of carbon sequestration potential (CSP), Gmelina arborea had the highest rate of aboveground C sequestration (3.59 Mg C ha-1 year-1). The SOC stocks in whole soil for the land use systems from the two districts ranged from 43-67 Mg C ha-1. The degraded ngitili did not show a reduction in SOC stocks despite reducing aboveground biomass C stocks by 15.11 Mg C ha-1. SOC in the woodlots were found to be associated more with the micro and silt-and clay-sized aggregates than the macroaggregates, reflecting high stability of SOC in the woodlot systems. The XANES C K-edge spectra revealed the stabilization of recalcitrant aromatic C compounds in the silt and clay-sized aggregates. This study demonstrates the significant contributions of woodlots in biomass C accumulation as well as long-term SOC stabilization in soil fractions. Thus, these agroforestry practices hold promise to meet household energy needs while contributing to climate change mitigation and adaption.

The broad objective of this thesis involves investigation of the role agriculture might play in a society wide greenhouse gas emissions reduction effort. Specifically, the breakeven price for carbon emission offsets is calculated for agriculturally based emission reducing practices. The practices investigated in the Texas High Plains involve reduced tillage use, reduced fallow use, reduced crop fertilization, cropland conversion to grassland, feedlot enteric fermentation management and digester based dairy manure handling. Costs of emission reductions were calculated at the producer level. The calculated offset prices are classified into four cost categories. They are: negative cost, low cost (less than $20 per ton of carbon saved), moderate cost ($20 through $100 per ton of carbon saved), and high cost (over $100 for tons of carbon saved). Negative cost implies that farmers could make money and reduce emissions by moving to alternative practices even without any carbon payments. Alternatives in the positive cost categories need compensation to induce farmers to switch to practices that sequester more carbon. All fallow dryland crop practices, dryland and irrigated cotton zero tillage, dryland and irrigated wheat zero tillage, irrigated corn zero tillage, cotton irrigated nitrogen use reduction under minimum tillage and dryland pasture for all systems, and anaerobic lagoon complete mix and plug flow systems fall in the negative cost category. Dryland and irrigated wheat under minimum tillage are found to be in the low cost category. Cotton dryland under minimum tillage and cotton irrigated with nitrogen use reduction under zero tillage fell into the moderate cost class. Both corn and cotton irrigated minimum tillage are found to be in the high cost category. This study only considers the producer foregone net income less fixed costs as the only cost incurred in switching to an alternative sequestering practice. More costs such as learning and risk should probably be included. This limitation along with other constraints such as use of short run budget data, lack of availability and reliability of local budgets, overlooking any market effects, and lack of treatment of costs incurred in selling carbon offsets to buyers are limitations and portend future work.

Land-use change, and in particular tropical deforestation, is the leading cause of species extinctions globally, and is the second most important source of CO2 emissions after fossil fuel combustion. I examine two policy-relevant questions that relate to tropical deforestation and land use change: (1) At regional scales, what biophysical and infrastructure-related factors are associated with deforestation? and (2) At a local scale, what are some of the impacts of land use change on above- and below-ground carbon stocks and on tree-species richness? The first question was examined for the Brazilian Amazon through spatially-explicit correlation analyses of deforestation and a series of predictor variables that included highways and roads, annual rainfall, dry season length, soil characteristics, site accessibility, and population density. The proximity of a site to roads and highways was the strongest predictor of deforestation, with more accessible sites more likely to be deforested. Dry season length was also a strong, positive predictor of deforestation. The results suggest that current plans to expand road infrastructure in Amazonia will have a significant impact on the forests of the areas transected. / The second question was examined in the context of a 3,198 ha area in Eastern Panama that is managed collectively by an Indigenous Embera community.

Reforestation is being considered as a mitigation option to help combat the climate change predicted to result from atmospheric carbon dioxide pollution. Forestry-based carbon storage projects are being introduced in many tropical countries, and assessment of species-specific carbon storage potentials is made difficult by a lack of species-level information. This study focuses on teak (Tectona grandis), to measure many of the characteristics affecting the carbon storage potential both of the trees themselves and of the plantations they are in. Root-to-shoot ratio, above- and belowground biomass, as well as tissue carbon content were measured in 20-year-old teak trees in Panamanian plantations. A regression relating diameter at breast height (DBH) to total tree carbon storage for trees of various sizes was developed. To scale up to the plantation level, this regression was used to estimate the carbon storage of the trees of four plantations. Litter, undergrowth, and soil were studied to estimate carbon storage in these compartments. These estimates were collated to form a global estimate of carbon storage in Panamanian harvest age teak plantations. Various methods of calculation of carbon storage in short-rotation plantations are discussed. This work will allow greater precision in the assessment of carbon storage in individual plantations.

Rates of carbon and peat accumulation were studied in a series of peat landforms within discontinuously frozen peatlands near Fort Simpson, Northwest Territories. An extended distribution of the White River volcanic ash layer was used as a chronostratigraphic horizon to ensure a consistent time span of peat deposition among peat cores and to allow a large core sample size without the expense of radiocarbon dating. Apparent recent carbon accumulation rates measured over the past 1200 years were not significantly different among rich fen, peat plateau, and collapse fen (means 13--14 g C M-2 yr-1). Poor fen and bog mean accumulation rates were 20--22 g C M-2 yr -1 and were not significantly different from each other. Microtopography and water table position appear to be important controls on both carbon and vertical peat accumulation rates. A regional survey incorporating measurements from other parts of the southwestern Northwest Territories and the southeastern Yukon shows rates similar to those near Fort Simpson. / The aggradation of permafrost results in 50 and 65% decreases in carbon and vertical peat accumulation rates, respectively. Carbon and peat accumulation continue to decrease significantly with both increasing permafrost maturity and the number of ground fires. The internal degradation of permafrost results in nearly a doubling in carbon accumulation rates, yet permafrost degradation at the margins of a peat plateau results in carbon accumulation rates similar to the peat plateau. / Clymo's (1984) carbon accumulation model was applied to cores from each landform in addition to a core spanning the entire developmental history of the peatland. Results indicate that true carbon accumulation and sequestration efficiency rates in ombrotrophic peatlands are lower in the upper Mackenzie Valley than for other boreal regions, primarily owing to high decomposition rates. The cessation of carbon accumulation is being approached. The model also serves to highlight the dangers of using apparent and true carbon accumulation rates interchangably. / Apparent and true carbon accumulation rates are significantly lower than published rates from other parts of northern Canada, Finland, and the Former Soviet Union. Low and variable summer precipitation in the region may be a significant factor through increased aerobic decomposition and/or decreased plant production caused by moisture stress.