UA cloudflare authentication

Browsing by Author "Amini, Shahriar S"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A Novel Method for the Integration of a Low Temperature Direct Air Capture with an Air Source Heat Pump
    (University of Alabama Libraries, 2023) Ilojianya, Valentine Ikenna; Amini, Shahriar S
    Climate change poses a significant challenge, demanding innovative strategies for mitigation. Integrated assessment models stress the urgency of employing technology to remove carbon dioxide from the atmosphere, making Direct Air Capture (DAC) a prominent method. DAC's success relies on providing heat to release captured CO2 in its operational cycle. This study introduces a novel approach, utilizing Air Source Heat Pumps (ASHP), a well-established technology that extracts heat from the air to generate steam, facilitating CO2 capture. A critical advancement is the use of a transcritical cycle ASHP, capable of producing 100°C steam, aligning with DAC's thermal needs during regeneration. Through process modeling, an integrated ASHP and DAC system, using the sorbent TRI-PE-MCM-41 with a carbon capture rate of 1100 kg/day, is proposed. This system not only supplies thermal energy for CO2 desorption but also cools the sorbent, aligning with DAC processes. The ASHP generates steam for CO2 desorption, enhancing energy efficiency. Environmental sustainability is a priority, and low ozone depletion and low global warming potential working fluids like CO2 and Isobutane are assessed for ASHP operation. ASHPs delivering 100°C steam significantly improve DAC efficiency, reducing energy consumption in the DAC compressor and fans. This results in energy savings of 22.54% (with CO2) and 61.05% (with Isobutane) and potential cost savings of up to $40.27 per ton of captured CO2. Importantly, this integrated technology is adaptable to various sites, requiring only an electrical power supply for ASHP operation, making it an environmentally responsible solution. The study also explores the feasibility of using photovoltaic panels to meet the electricity needs of the ASHP.
  • Thumbnail Image
    Item
    Sustainable Organosolv Pretreatment and Fractionation of Lignocellulosic Biomass with the Aim of Subsequent Utilization of the Fractionated Components
    (University of Alabama Libraries, 2025) Agwu, Kelechi Andrew; Sheehan, James D
    Lignocellulosic biomass is the most abundant biomass species on Earth. However, lignocellulose biomass is challenging to exploit because the biochemical components (cellulose, 40-60 wt.%; hemicellulose, 10-40 wt.%; and lignin, 15-30 wt.%) form the lignin-carbohydrate complex (LCC) that supports the growth of the plant/crop but also makes them recalcitrant to valorization. To overcome this recalcitrance and to exploit lignocellulose biomass for biofuels and biochemicals, pretreatment (fractionation or pulping) is often carried out. This procedure is aimed at breaking apart the lignin-carbohydrate linkages (LCC) and dissolving the lignin, leaving a pulp rich in cellulose. In traditional pretreatment methods, the lignin fractions are usually of low grade, primarily due to their condensed nature and the incorporation of sulfur in some cases. One of the major ways to sustainably pretreat biomass and produce high-quality lignin is through organosolv pulping. Traditional organosolv processes utilized volatile solvents (VOCs) like ethanol, methanol, and acetone, but, due to the rising concerns about the release of these VOCs into the environment, alternative high-boiling point solvents are being proposed. Hence, this research started by using available high-boiling point polar aprotic solvents as sustainable options for organosolv pretreatment of lodgepole pine (a representative lignocellulose). It was shown for the first time that the combination of these solvents with organic bases as additives effectively removes lignin from biomass. Concurrently, a modeling approach was employed to study the kinetics of lignin removal from lodgepole pine using these polar aprotic solvents. Thereafter, the research extended to using novel biobased solvents based on the glycerol backbone and termed glycerol-derived ethers (GDEs) as sustainable solvent options for organosolv fractionation of lodgepole pine. The dried pulp and the isolated lignin were extensively analyzed, demonstrating for the first time a novel solvent system for biomass fractionation. Furthermore, to improve the utilization of fractionated lignocellulose components (cellulose, lignin), this work extends to integrating them into biobased composite materials, specifically, lignin-based epoxides and cellulosic materials with improved mechanical and barrier properties. Finally, future research goals related to improving the sustainability of the novel solvent systems for biomass fractionation and materials utilization were proposed.