Harmonization of reported life-cycle and techno-economic algal biofuel process results
Date
2017
Authors
Beckstrom, Braden D., author
Cruce, Jesse R., author
Somers, Michael D., author
Chen, Peter H., author
Quinn, Jason C., author
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Abstract
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.
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Subject
LCA
TEA
algae
biofuels
sustainability