Techno-Economic Uncertainty Analysis of Wet Waste-to-Biocrude via Hydrothermal Liquefaction
Wet waste hydrothermal liquefaction (HTL) has the potential to make economically competitive biocrude due to low cost and widely available feedstock, process flexibility, and high product selectivity and quality. However, most of the current understanding of HTL technology is based on batch testing of algal and woody biomass, with few studies available on continuous processing of wet waste. These knowledge gaps, along with lack of commercial demonstration, can lead to significant uncertainties, potential bias in process design, and limited accuracy of economic projections. In this work, stochastic techno-economic analysis (TEA) was conducted to evaluate the economic feasibility and risks of the wet waste HTL process by leveraging our previous uncertainty quantification work on algae HTL and in-house wet waste HTL continuous system testing data. A “component additivity” model was developed to predict HTL product yields and qualities from different wet waste compositions. With the established HTL yield model, a process reduced-order model (ROM) coupled with an economic model was built in Microsoft Excel® to replace the rigorous but computationally intensive Aspen Plus® model for uncertainty analysis. The proposed stochastic TEA approach using the ROM reduces computational time for the analysis by 2000 times, compared to the full Aspen-based model. Monte Carlo simulation was conducted to quantify the economic uncertainties from feedstock composition, HTL yield model, aqueous-phase product treatment, utility consumption, and equipment sizing and costing. For the base case applied to the current state of technology (SOT) [1] , the minimum biocrude selling price (MBSP) is approximately $3.27 per gge (gasoline gallon equivalent). This price is close to the original MBSP of $3.11 per gge estimated for the SOT [1]. Based on the reasonable uncertainty assumptions of the current technology, the stochastic TEA indicates the MBSP for wet waste HTL ranges from $2.65/gge to $4.93/gge (10th and 90th percentiles) with a median of $3.55/gge. Feed moisture, HTL reactor model, and capital investment are the main contributors to the economic uncertainty of the wet waste HTL process. Uncertainty in the MBSP could be reduced by roughly 50% if uncertainties in the feed moisture and HTL reaction yield model can be effectively controlled or decreased.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1762699
- Report Number(s):
- PNNL-SA-156267
- Journal Information:
- Applied Energy, Vol. 283
- Country of Publication:
- United States
- Language:
- English
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