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Browsing by Author "Cruce, Jesse R., author"

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    Economic viability of multiple algal biorefining pathways and the impact of public policies
    (Colorado State University. Libraries, 2018) Cruce, Jesse R., author; Quinn, Jason C., advisor; Bradley, Thomas, committee member; Burkhardt, Jesse, committee member
    This study makes a holistic comparison between multiple algal biofuel pathways and examines the impact of co-products and methods assumptions on the economic viability of algal systems. Engineering process models for multiple production pathways were evaluated using techno-economic analysis (TEA). These pathways included baseline hydrothermal liquefaction (HTL), protein extraction with HTL, fractionation into high-value chemicals and fuels, and a small-scale first-of-a-kind plant coupled with a wastewater treatment facility. The impact on economic results from policy scenarios was then examined. The type of depreciation scheme was shown to be irrelevant for durations less than 9 years, while short-term subsidies were found to capture 50% of the subsidy value in 6 years, and 75% in 12 years. Carbon prices can decrease fuel costs as seen by the production facility through carbon capture credits. TEA tradeoff assessments determined that $7.3 of capital costs are equivalent to $1 yr-1 of operational costs for baseline economic assumptions. Comparison of algal fuels to corn and cellulosic ethanol demonstrates the need for significant co-product credits to offset high algal capital costs. Higher value co-products were shown to be required for algal fuel economic viability.
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    Harmonization of reported life-cycle and techno-economic algal biofuel process results
    (Colorado State University. Libraries, 2017) Beckstrom, Braden D., author; Cruce, Jesse R., author; Somers, Michael D., author; Chen, Peter H., author; Quinn, Jason C., author
    The large range of reported values of life-cycle assessments (LCA) and techno-economic assessments (TEA) in the algal biofuels research field is concerning. This wide range of results creates difficulties when attempting to directly compare different processes and technologies across publications. This project attempts to rectify this difficulty by unifying the diverse methods of reporting results within this research sector. A harmonization of life-cycle assessments was completed for 20 published journal articles. Harmonization included the standardization of units to MJ/kg algae for Net Energy Ratio (NER) and gCO2-eq/kg algae for Global Warming Potential (GWP), results to a growth rate of 25 g/m2/day, and a Well-to-wheels (WTW) system boundary. Implementation of these standardized assumptions and system metrics produced a significant decrease in the range of reported values for both the NER (the energy input required to produce 1 MJ of fuel output) and GWP (g CO2-equivalent / MJfuel). Similarly, 22 models were developed from 9 publications and harmonized by TEA methodology and growth rates, using the standard assumptions from the Bioenergy Technologies Office (BETO). A second TEA harmonization examining only downstream conversion technologies was performed by standardizing the cost of algal biomass. TEA results suggest that future economic modeling efforts should include a BETO assumptions baseline case for better comparisons to other published work. Additionally, a productivity of 25 g/m2/day is a suitable baseline yield for analysis, as higher productivities result in diminishing returns for TEA results, but lower productivities skew the results significantly. Finally, harmonizing algal biomass cost for input into downstream conversion technology evaluations allows for more effective cross-technology comparisons by significantly reducing the range of results. Harmonization work like this effort can help more effectively determine which production pathways and technologies have the best future potential.