CBE Doctoral Dissertation Defense: “A Multifaceted Approach to CO2 Emissions Reductions and Removals” (Maxwell Pisciotta)

Abstract:
The scientific consensus is that climate change is not only actively occurring, but that it is irrevocably due to human activities associated with greenhouse gas emissions. Greenhouse gas emissions have been accumulating in the atmosphere since the beginning of the industrial revolution. This thesis specifically focuses on one greenhouse gas in particular, CO 2 . The continued CO 2 emissions from human activity can be quantified with the atmospheric concentration, which amounts to upwards of 420 ppm today. To mitigate the harmful impacts of climate change, these CO 2 emissions must be mitigated, through pathways such as reducing their initial generation, capturing them when they are unable to be avoided, and removing them from the atmosphere when they cannot be captured at the source. This thesis investigates different technologies that fit into these broad categories, notably, deploying carbon capture technologies on natural gas combined cycle power plants, decarbonizing industrial sectors, and pairing direct air capture technologies to geothermal energy. To readily address the CO 2 emissions from natural gas combined cycle power plants, a novel approach of using thermal energy storage was developed and evaluated to ensure its technological performance and economic viability. By integrating natural gas combined cycle power plants with carbon capture and storage (CCS) and thermal energy storage opportunities, the economic viability of these plants improve. This was measured using the net present value of each of the configurations assessed over real-world locational marginal pricing (LMP) signals from NYISO and CAISO. Of the thermal energy storage options, eight of the 19 thermal energy storage configurations led to an increased net present value on 11.5% – 98% of the LMP signals. Additionally, a framework was developed and used to identify opportunities to integrate direct air capture (DAC) systems with geothermal energy resources to maximize the CO 2 abatement potential. The Geothermal-Framework can be used with various geothermal resources ranging from 86ºC – 225ºC, using various working fluids, and brine salinity ranging from 0-6%. When the integration of geothermal energy and DAC systems are compared to geothermal energy being used to generate low-carbon electricity, the CO 2 abatement potential is increase by 105% to 452% when geothermal energy is integrated with DAC systems. This illustrates beneficial synergies between the two technologies, namely being able to use geothermal energy as thermal energy rather than solely converting it to electricity. Lastly, the Geothermal-DAC Framework was used to showcase opportunities for integrating DAC with the geothermal resources near Gerlach, NV, in preparation for a community meeting. The community feedback was then incorporated, facilitating updates to the Geothermal-DAC Framework to account for community needs, illustrating that engineering can be community-centered from the start of the project. All the approaches explored in this thesis highlight the need for a diverse portfolio of solutions to address the ongoing CO 2 emissions and abatement required to avoid the most harmful impacts of climate change. Furthermore, the efforts of researchers, scientists, policymakers and frontline communities will be needed in concert to deploy a portfolio that meets the needs to address climate change and protect against further environmental injustices.