Theses and Dissertations
This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students.
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- All Subjects: Environmental engineering
- Creators: Lackner, Klaus S
Description
Carbon dioxide (CO2) is one of the most dangerous greenhouse gas. Its concentration in the atmosphere has increased to very high levels since the industrial revolution. This continues to be a threat due to increasing energy demands. 60% of the worlds global emissions come from automobiles and other such moving sources. Hence, to stay within safe limits, it is extremely important to curb current emissions and remove those which have already been emitted. Out of many available technologies, one such technology is the moisture swing based air capture technology that makes use of resin material that absorbs CO2 when it is dry and releases it when it is wet. A mathematical model was developed to better understand the mechanism of this process. In order to validate this model, numerical simulation and experimentation was done. Once the mechanism was proved, it was seen that there are many factors and parameters that govern this process. Some of these do not have definite value. To find the best fit value for these parameters, an optimized fitting routine needs to be developed that can minimize the standard deviation of the error. This thesis looks into ways in which the optimization of parameters can be done and the possible future work by using substantial data.
ContributorsChopra, Vinuta (Author) / Lackner, Klaus S (Thesis advisor) / Fox, Peter (Committee member) / Wright, Allen (Committee member) / Arizona State University (Publisher)
Created2016
Description
This paper will explore the existing relationship between direct air capture (DAC)technology and energy justice (EJ) principles. As DAC is a nascent technology that is
transitioning from the R&D phase to the deployment phase, a standard for typical scaling
practices has not yet been established. Additionally, since the industry of DAC aims to
capture at least 10 gigatonnes of carbon dioxide per year by 2050, and at least 20 Gt/yr by
2100, the scaling practices of this technology will have a significant impact on
communities around the world. Therefore, in this thesis I argue that if DAC is not scaled
equitably, it will negatively impact the communities hosting the technology, and would
develop a negative reputation which could slow down the overall scaling process. On the
flip side, if DAC is scaled equitably, then it could create a positive effect by being
deployed in underserved and marginalized communities and providing an economic
benefit. This could result in DAC having a positive reputation and scaling more rapidly.
In order to understand how the field viewed the integration of EJ principles into the
scaling process, I interviewed representatives from DAC companies, experts in energy
justice from NGOs and academia, and local government officials. These interviews were
semi-structured, open-ended and conducted anonymously. Through these interviews I
was able to refine my arguments and put forward a set of guidelines that the industry
could use to scale DAC with equity and justice as core principles.
ContributorsSriramprasad, Vishrudh (Author) / Lackner, Klaus S (Thesis advisor) / Miller, Clark (Committee member) / Green, Matt (Committee member) / Hanemann, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
CO2 capture from ambient air (often referred to as direct air capture or DAC) is one of the Carbon Dioxide Removal methodologies that may limit Global Warming. High energy demand and high cost are currently serious barriers for large-scale DAC deployments. Moisture-controlled CO2 sorption is a novel technology for DAC, where CO2 sorption cycles are driven solely by changes in surrounding humidity. In contrast to traditional temperature-swing adsorption cycles, water is a cheaper source of exergy than high-grade heat or electricity and moisture-controlled CO2 sorption may reduce the cost of DAC. However, analytic models that describe this sorption system have not been well established, especially in a quantitative manner. In this dissertation the author first establishes both static and kinetic models analytically with bottom-up approaches from the governing equations. These models are of scientific interest and also of industrial importance. They were validated by literature data and custom experiments. In a second part of the dissertation, the author explores the application of moisture-controlled materials in the form of membranes that actively pump CO2 against a concentration gradient. These explorations are guided by the quantitative models developed in the first part of the dissertation. In CO2 separation technologies relying on actively pumping membranes, a moisture-controlled CO2 sorbent is used as either a gas-gas membrane contactor or a gas-liquid membrane contactor. The author experimentally and theoretically determined that a specific commercial anion exchange membrane that was considered a plausible candidate does not satisfy the requirements for such an active membrane as a consequence of its slow kinetics of carbon transport. Requirements for materials to serve as active membranes have been clarified, which is of great interest for industrial application and will provide a starting point for future material design and development.
ContributorsKaneko, Yuta (Author) / Lackner, Klaus S (Thesis advisor) / Green, Matthew D (Thesis advisor) / Dirks, Gary W (Committee member) / Wade, Jennifer L (Committee member) / Freeman, Benny D (Committee member) / Arizona State University (Publisher)
Created2022