The objective of this study was to examine some mechanisms of bottomland hardwood afforestation and their impacts on above- and belowground carbon sequestration. Six combinations of bottomland hardwood species and two levels each of fertilizer and herbicide were applied in a completely randomized design on two sites in the LMAV. Survival, ground line diameter and total height were monitored for two growing seasons. Soil carbon and nitrogen to a depth of one meter, herbaceous biomass, and tree biomass were sampled in the first and second years of establishment. Species mixes, fertilizer, and herbicide application significantly affected survival, growth, above- and belowground tree biomass carbon after two years of establishment. Survival was generally average, while growth for most species mixes was below expectation. Species mixes E (green ash/oak mix) and F (NRCS species mix) had the highest tree vegetation carbon both above- and belowground. Soil carbon and nitrogen were not significantly affected by any treatments.

No description available.

A recent concern is the cause and effect of global climate change. Many institutions give credit for these changes to the increased levels of greenhouse gases in the atmosphere, in particular the increase in the amount of carbon dioxide present. There is a growing interest in carbon capture and storage (CCS) as a means to reduce the global impact of CO₂ on the climate as a greenhouse gas. Carbon capture is the process of removing CO₂ from the atmosphere as well as preventing it from entering the atmosphere by means of exhaust. The captured carbon is stored underground in reservoirs. These reservoirs have the storage space to handle the volume of CO₂ injected as well as a caprock layer preventing the injection fluid from returning to the surface. Additionally, CO₂ can be used for enhanced oil recovery (EOR). To monitor the injection sites used for the CO₂ storage or EOR process, the integrity of the caprock as well as the surrounding rock formations are the locations of interest. Knowing when a joint or a fracture is going to slip is necessary to prevent major failures within geologic strata. It is necessary to prevent these slips from occurring to retain the integrity of the caprock, which is keeping the fluid within the reservoirs. Passive acoustic emissions monitoring was used to determine how effectively failure locations could be located in three unique tests. Coupled with double difference tomography, the failure of a Berea Sandstone sample and Marcellus Shale sample were calculated to determine how well the stress redistribution within the sample could be mapped using the recorded data. For the main indenter tests two samples were tested, a piece of Berea Sandstone and a piece of Marcellus Shale. The secondary test was a transform shear test using sandstone, and the third test for caprock upheaval test attempted to recreate the failure of caprock due to injection pressure. For all tests, the samples were monitored using acoustic emissions software until failure or it was deduced that the test would not produce failure. The secondary tests did not progress through the data analysis as far as the indentation tests, however valuable information was gathered from these tests. The shear test demonstrated the effectiveness of the passive acoustic emissions monitoring system to record shear failure. This test provides confidence in this technology to record and located events that are not occurring in compression. The caprock upheaval tests were not successful in causing failure in the caprock, however during the testing the passive acoustic emissions monitoring system was able record and locate events that occurred within the sample around the boundary on the reservoir. At the reservoir boundaries there was evidence of fluid flowing through the reservoir, and the events align with these locations. This positive result shows that the monitoring system is able to locate events induced by fluid injection. The results of these tests provide confidence in the passive acoustic emissions monitoring system to record accurate data for the caprock integrity monitoring. The tomograms created from the recorded data accurately imaged the areas of interest within the rock samples. From these results, passive acoustic emissions monitoring systems coupled with double difference tomography has proven capable of monitoring homogeneous samples within a laboratory environment. With further testing, this technology could possibly be a viable option for monitoring carbon sequestration sites. / Master of Science

In the wake of concerns about the long-term integrity and containment of sub-surface CO₂ sequestration reservoirs, many efforts have been made to improve the monitoring, verification, and accounting methods for geo-sequestered CO₂. This Ph.D. project has been part of a larger U.S. Department of Energy (DOE) sponsored research project to demonstrate the feasibility of a system designed to tag CO₂ with radiocarbon at a concentration of one part per trillion, which is the ambient concentration of ¹⁴C in the modern atmosphere. Because carbon found at depth is naturally free of ¹⁴C, this tag would easily differentiate pre-existing carbon in the underground from anthropogenic, injected carbon and provide an excellent handle for monitoring its whereabouts in the subsurface. It also creates an excellent handle for adding up anthropogenic carbon inventories. Future inventories in effect count ¹⁴C atoms. Accordingly, we developed a ¹⁴C tagging system suitable for use at the part-per-trillion level. This tagging system uses small containers of tracer fluid of ¹⁴C enriched CO₂. The content of these containers is transferred into a CO₂ stream readied for underground injection in a controlled manner so as to tag it at the part-per-trillion level. These containers because of their shape are referred to in this document as tracer loops. The demonstration of the tracer injection involved three steps. First, a tracer loop filling station was designed and constructed featuring a novel membrane based gas exchanger, which degassed the fluid in the first step and then equilibrated the fluid with CO₂ at fixed pressure and fixed temperature. It was demonstrated that this approach could achieve uniform solutions and prevent the formation of bubbles and degassing downstream. The difference between measured and expected results of the CO₂ content in the tracer loop was below 1%. Second, a high-pressure flow loop was built for injecting, mixing, and sampling of the fast flowing stream of pressurized CO₂ tagged with our tracer. The laboratory scale evaluation demonstrated the accuracy and effectiveness of our tracer loops and injection system. The ¹⁴C/¹²C ratio we achieved in the high pressure flow loop was at the part per trillion level, and deviation between the experimental result and theoretical expectation was 6.1%. Third, a field test in Iceland successfully demonstrated a similar performance whereby ¹⁴CO₂ tracer could be injected in a controlled manner into a CO₂ stream at the part per trillion level over extended periods of time. The deviation between the experimental result and theoretical expectation was 7.1%. In addition the project considered a laser-based ¹⁴C detection system. However, the laser-based ¹⁴C detection system was shown to possess inadequate sensitivity for detecting ambient levels of ¹⁴CO₂. Alternative methods for detecting ¹⁴C, such as saturated cavity absorption ring down spectroscopy and scintillation counting may still be suitable. In summary, the project has defined the foundation of carbon-14 tagging for the monitoring, verification, and accounting of geological carbon sequestration.

In order to reduce the rate of climate change, particularly global warming, it is imperative that industries reduce their carbon dioxide (CO2) emissions. A promising solution of CO2 emission reduction is Carbon dioxide Capture and Storage (CCS) by sequestration, which involves isolating and extracting CO2 from the flue gases of various industrial processes, and thereafter burying the CO2 underground. The capture of CO2 proved to be the most challenging aspect of CCS. Thus, the objective of this research was to identify the most promising solution to capture CO2 from industrial processes. The study focussed on capturing CO2 emitted by coal power plants, coal-to-liquids (CTL) and gas-to-liquids (GTL) industries, which are common CO2 emitters in South Africa. This thesis consists firstly of an extensive literature review detailing the above mentioned processes, the modes of CO2 capture, and the various CO2 capture methods that are currently being investigated around the world, together with their benefits and drawbacks in terms of energy penalty, CO2 loading, absorption rate, capture efficiency, investment costs, and operating costs. Modelling, simulation, and pilot plant efforts are also described. The study reviewed many CO2 capture techniques including solvent absorption, sorbent capture, membrane usage, hydrate formation, and newly emerging capture techniques such as enzyme based systems, ionic liquids, low temperature cryogenics, CO2 anti-sublimation, artificial photosynthesis, integrated gasification steam cycle (IGSC), and chemical looping combustion The technique of solvent absorption was found to be the most promising for South African industries. Vapour-liquid-equilibrium (VLE) measurements of solvent absorption using amine blends were undertaken, using blends of methyl-diethanol amine (MDEA), diethanol amine (DEA) and water (H2O) with composition ratios of 25: 25: 50 wt% and 30: 20: 50 wt% respectively, and with CO2 and N2 gases at CO2 partial pressures of 0.5 to 10.5 bar. Experiments were conducted under system pressures of 5 to 15 bar and temperatures of 363.15 and 413.15 K, using a static analytic apparatus. CO2 liquid loading results were analysed and discussed. The experimental data were regressed in Matlab (R2009b) using the Posey-Tapperson-Rochelle model and the Deshmukh-Mather model. The Matlab programmes are presented along with the regressed binary interaction and model parameters. The accuracy of model predictions are discussed. Thereafter an Electrolyte-NRTL model regression and simulation of the absorption process was conducted using Aspen Plus V 7.1. for flue gas compositions, solvent compositions, temperature, and pressure conditions similar to that of process operating conditions. CO2 loading, design factors, CO2 recovery, and CO2 purity results were analysed and compared where appropriate, with experimental results. Finally a general preliminary energy efficiency and cost analysis was conducted based on the simulation results. The main conclusions reached are that the amine solvent blend containing 25:25:50 wt% of MDEA:DEA:H2O, produced higher CO2 loadings for its respective system conditions than other solvents studied and those found in literature. However, absorption of CO2 was found to be highly dependent on system temperature and pressure. The Deshmukh-Mather model provided higher accuracy than the Posey-Tapperson-Rochelle model, producing CO2 loading predictions with a relative error not exceeding 0.04%, in 1.5 to 3 minutes using a dual core processor. Aspen absorption simulations provided significantly lower CO2 loading results than those experimentally obtained, due to the low contact time achieved and higher temperature dependence in the proposed absorption process. Process improvements were highlighted and implemented to increase CO2 recovery and purity. Energy penalty values were found to be higher than those found in literature, but room for process and design improvement was identified and recommendations were given. Investment cost estimates were found to be justifiable and within reason. Limitations of the simulation were also identified and discussed. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

Water management that alters riverine ecosystem processes has strongly influenced deltas and the people who depend on them, but a full accounting of the trade-offs is still emerging. Using palaeoecological data, we document a surprising biogeochemical consequence of water management in the Colorado River basin. Complete allocation and consumptive use of the river's flow has altered the downstream estuarine ecosystem, including the abundance and composition of the mollusc community, an important component in estuarine carbon cycling. In particular, population declines in the endemic Colorado delta clam, Mulinia coloradoensis, from 50-125 individuals m(-2) in the pre-dam era to three individualsm-2 today, have likely resulted in a reduction, on the order of 5900-15 000 tCyr(-1) (4.1-10.6 mol Cm-2 yr(-1)), in the net carbon emissions associated with molluscs. Although this reduction is large within the estuarine system, it is small in comparison with annual global carbon emissions. Nonetheless, this finding highlights the need for further research into the effects of dams, diversions and reservoirs on the biogeochemistry of deltas and estuaries worldwide, underscoring a present need for integrated water and carbon planning.

Doctor of Philosophy / Department of Agronomy / Ganga M. Hettiarachchi / Soil carbon (C) sequestration has been recognized as one of the most effective potential mitigation options for climate change. Underlying mechanisms of soil C sequestration/preservation is poorly understood, even after decades of soil C research. The main research objectives of this dissertation were three-fold: (1) enhancing our understanding in mineralogical and physicochemical mechanisms of soil C sequestration in microaggregates, (2) understanding the chemistry of organic C sequestered in soil aggregates, and (3) to determine the resilience of C to different temperature-moisture regimes and physical disturbance in a six-month incubation. An integrated approach was used in obtaining a better picture on mechanisms of C preservation. Two long-term agroecosystems located at the North Agronomy Farm, Manhattan, KS (Mollisols) and the Center of Experimentation and Research Fundacep in Cruz Alta-RS, Brazil (Oxisols) were used. Main plots of both systems were till and no-till. Mollisols consisted of three fertilizer treatments; control, manure/compost and urea. Oxisols had three different crop rotations; simple, intermediate, and complex. Submicron level information gathered by spectromicroscopy approaches, identified the direct preservation of OC structures with the original morphology; suggesting that the preservation of OC is a primary mechanism of C sequestration in these soils. Physical protection and organo-mineral associations seemed to also be involved in OC preservation. Manure/compost addition and no-till favored labile C preservation in aggregates of Mollisols. Significant associations observed between reactive minerals and C pools in Mollisols indicated the significance of organo-mineral associations in OC preservation. Large microaggregates exerted strong C preservation through physical protection and organo-mineral associations. Unlike in Mollisols, Oxisols showed a poor correlation between reactive mineral fraction and organic C which indicated the significance of physical protection over organo-mineral associations. Resilience of sequestred C was significantly affected by temperature across both temperate and tropical soil ecosystems, directly and indirectly. High temperature influenced soil acidity and reactive minerals, ultimately affecting organo-mineral associations. Macromolecular propeties of humic acid fraction showed changes after six months. Overall, direct and indirect evidence from this study suggested that the preservation of SOC is an ecosystem property supporting the newly proposed theories in soil C dynamics.

Soil organic carbon (SOC) is important not only for improving soil quality but also for contributing to climate change mitigation in agriculture. However, net greenhouse gas (GHG) balances, including methane (CH4) and nitrous oxide (N2O), need to be considered, as practices that increase SOC might increase GHG emissions. Sustainable use of soil resources needs to be assessed over long time periods and across spatial scales; biogeochemical models are useful tools to estimate GHG emissions and corresponding mitigation potentials. A process-based, ecosystem model DayCent that simulates soil carbon and nitrogen dynamics from diverse agroecosystems, has been applied to observe SOC sequestration, GHG emissions and yield in a contrasting climatic region UK and Bangladesh agriculture. The study mainly focus on determination of GHG mitigation potentials under improved management practices in rice based cropland Bangladesh. We hypothesized that alternative management would increase SOC and reduce net GHG emissions. As crop yield is the most important variable for Bangladesh, it was includes in the simulations. Since site test simulations under different management using the DayCent model were satisfactory, the model was used to simulate GHG covering 64 districts of Bangladesh, considering climate, soil and SOC content for the period 1996-2015. An integrated management scenario consisting of irrigation, tillage with residue management, reduced mineral nitrogen fertilizer and manure application increased annual SOC stocks, and offset net GHG emissions while maintaining yield. The model outcome suggests that the “4 per mille” target is feasible for Bangladesh. It is also possible to contribute to the GHG reduction target by 2030 set by policy makers.

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 100-106). / Climate change is a threat that could be mitigated by introducing new energy technologies into the electricity market that emit fewer greenhouse gas (GHG) emissions. We face many uncertainties that would affect the demand for each of these technologies in the future. The costs of these technologies decrease due to learning-by-doing as their capacity is built out. Given that we face uncertainties over future energy demands for particular technologies, and that costs reduce with experience, an important question that arises is whether policy makers should encourage early investments in technologies before they are economically competitive, so that they could be available in the future at lower cost should they be needed. If society benefits from early investments when future demands are uncertain, then there is an option value to investing today. This question of whether option values exist is investigated by focusing on Coal-fired Power Plants with Carbon Capture and Storage (CCS) as a case study of a new high-cost energy technology that has not yet been deployed at commercial scale. A decision analytic framework is applied to the MIT Emissions Prediction Policy Analysis (EPPA) model, a computable general equilibrium model that captures the feedback effects across different sectors of the economy, and measures the costs of meeting emissions targets. Three uncertainties are considered in constructing a decision framework: the future stringency of the US GHG emissions policy, the size of the US gas resource, and the cost of electricity from Coal with CCS. The decision modeled is whether to begin an annual investment schedule in Coal with CCS technology for 35 years. Each scenario in the decision framework is modeled in EPPA, and the output measure of welfare is used to compare the welfare loss to society of meeting the emissions target for each case. The decision framework is used to find which choice today, whether to invest in CCS or not, gives the smallest welfare cost and is therefore optimal for society. Sensitivity analysis on the probabilities of the three uncertainties is carried out to determine the conditions under which CCS investment is beneficial, and when it is not. The study finds that there are conditions, specified by ranges in probabilities for the uncertainties, where early investment in CCS does benefit society. The results of the decision analysis demonstrate that the benefits of CCS investment are realized in the latter part of the century, and so the resulting optimal decision depends on the choice of discount rate. The higher the rate, the smaller the benefit from investment until a threshold is reached where choosing to invest becomes the more costly decision. The decision of whether to invest is more sensitive to some uncertainties investigated than others. Specifically, the size of the US gas resource has the least impact, whereas the stringency of the future US GHG emissions policy has the greatest impact. This thesis presents a new framework for considering investments in energy technologies before they are economically competitive. If we can make educated assumptions as to the real probabilities we face, then extending this framework to technologies beyond CCS and expanding the decision analysis, would allow policymakers to induce investment in energy technologies that would enable us to meet our emissions targets at the lowest cost possible to society. / by Eleanor Charlotte Ereira. / S.M.in Technology and Policy

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 138-140). / Carbon capture and sequestration (CCS) technology has the potential to be a key CO2 emissions mitigation technology for the United States. Several CCS technology options are ready for immediate commercial-scale demonstration, but three obstacles to commercial deployment remain: the lack of a clear legal and regulatory framework for sequestration, the lack of a demonstration phase, and most importantly, the lack of a market for CCS. A successful demonstration phase will achieve the goal of technology readiness. The demonstration phase should be organized so as to share costs and risks between public and private actors. Project selection responsibility should be assigned to a dedicated private board and project management responsibility to private companies. This analysis recommends a combination of the Boucher Bill proposal for a CCS demonstration phase, as incorporated in the American Clean Energy and Security Act (ACES Act) of 2009, and a continuation of the DOE Clean Coal Power Initiative program. This combined approach can provide productive competition between public and private demonstration programs. Achieving technology readiness will not on its own lead to commercial deployment of CCS. Two additional policy objectives for the commercial deployment phase are considered: market penetration and cost reduction. Market penetration can be ensured through strong market pull policies, but this may be a very expensive policy approach in the long run. A more prudent goal is long-term cost reduction of CCS. Unlike the market penetration goal, the cost reduction goal will not guarantee that CCS will become a major contributor to carbon emissions mitigation, but it will provide a more cost-effective path. Achieving the cost reduction goal will require strong market pull policies for the short and medium term, together with a focus on technology push policies over the entire period. In the long term, market pull policies for CCS should be eliminated; if CCS is not economically competitive with alternative technologies, it should not be deployed on a significant scale. The ACES Act provides a good policy framework to achieve technology readiness through a demonstration phase and to pursue the long-term goal of cost reduction for commercial deployment of CCS technology. This approach will provide a cost-effective strategy for ensuring that CCS, a major scalable option for carbon emissions mitigation, is given the best chance of success in the long term. / by Michael Roberts Hamilton. / S.M.in Technology and Policy