Beck, Andrew
(2018)
Co-production of Bio-based Fuels and Chemicals: Process Modeling and Anticipatory Lifecycle Environmental Impact Assessment.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Heralded as a technology to address anthropogenic climate change, resource renewability, and national energy security, biofuels and their many production pathways have continued to scale up and develop globally. While economic feasibility is always explicitly considered in designing biorefineries and supply chains, environmental performance is often evaluated retrospectively or assumed to improve on baseline petroleum fuels. As such, many early biofuel technologies resulted in unexpected environmental consequences, prompting researchers to propose systematic frameworks to conduct forward-looking “anticipatory” lifecycle assessments (LCA), to quantify environmental impacts during the design phase of biofuel production pathways. Such analyses have gained further utility as countries implement low-carbon fuel tax credits, requiring companies to quantify lifecycle greenhouse gas (GHG)emissions for biofuels and demonstrate reductions versus a similar petroleum fuel. Allowing for further improvements in environmental performance, specialty and commodity organic chemicals can also be derived from biomass feedstocks in tandem with fuel production. In light of these considerations, this work evaluates the environmental performance of an array of biorefinery designs that co-produce bio-based fuels and chemicals. Chemical process models and a prospective well-to-wheel LCA model of a two-step multistage torrefaction and catalytic upgrading system are constructed to quantify lifecycle GHG emissions and energy return on primary fossil energy investment (EROI-fossil) for a drop-in replacement biofuel product. Cyclopentanone, biochar, and a net electricity export are each generated as potential co-products, and assessed under market-based allocation and displacement methods. Across design cases, process performance metrics and LCA results are compared to evaluate trade-offs between process and environmental performance. LCA results are generated with measures of uncertainty, and undergo sensitivity analyses to identify the most influential model parameters. Modeling results suggest that insofar as markets allow, removing bio-chemicals upstream can
reduce hydrogen consumption, utilities consumption, and equipment sizing without excessive loss in fuel production – an integral step towards commercially feasible biorefineries. Finally, methodological limitations of accounting schemes for both GHG and EROIfossil are explored and discussed due to the distortions they produce under the co-production of fuels and chemicals. While GHG emissions may be better addressed via consequential LCA, co-product crediting
within EROI requires a full mathematical overhaul.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
24 January 2018 |
| Date Type: |
Publication |
| Defense Date: |
28 November 2017 |
| Approval Date: |
24 January 2018 |
| Submission Date: |
20 November 2017 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
74 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
biofuels, life cycle assessment, life-cycle assessment, lifecycle assessment, sustainability, systems analysis,
process modeling, greenhouse gas emissions, energy return on investment, torrefaction, cyclopentanone |
| Date Deposited: |
24 Jan 2018 18:32 |
| Last Modified: |
24 Jan 2019 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/33395 |
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