System Performance and Sustainability
The System Performance and Sustainability component of the SBAR project intends to understand the environmental impact and economic viability of the technologies being investigated. Specifically, we are developing engineering process models capturing all aspects of the agricultural and downstream production processes. Experimental data generated in the project is leveraged to validate the foundational engineering process model. Engineering impact and economic viability is being concurrently evaluated for both guayule and guar production processes. Results from this analysis are being used as feedback to experimental systems to identify performance targets to meet sustainability goals.
- Engineering Process Modeling
- Guar and Guayule Agricultural Modeling
- Guar Processing
- Guayule Processing
- Transportation Modeling
- Life Cycle Assessment
- Economic Viability
Engineering Process Modeling
The engineering process modeling work represents the foundation of the sustainability work, the focus of this work is to accurately capture the energy and mass flows across the entire value chain. Data from various team members is used for validation of different sub-processes operations. Modularity in construction supports the evaluation of various production pathways.
Guar and Guayule Agricultural Modeling
The agricultural sustainability team is developing a life cycle model to estimate environmental impacts for guar, guayule, and alternative crops such as Hevea. The agricultural research team is developing the costs to produce and establishing breakeven prices to grow guayule and guar as well as other alternative crops, which include winter wheat, cotton, alfalfa hay, barley, and corn. Inputs to both life cycle assessment (LCA) and cost models are very similar; as such the teams are collaborating to ensure that the models are harmonized with one streamlined inputs location. The models themselves, however, are quite different and require each team to construct separate models.
For the cost model, costs and breakeven prices are based on whole-farm, long-term scenarios that include changes to labor, fuel, repairs and maintenance costs for tractors and equipment as crops are planted or adopted. Some outputs from the cost model can be used as inputs for the LCA, and include hours of labor, amounts of fertilizer and chemical inputs, irrigation water usage, and tractor and equipment fuel requirements, as well as replacement costs. The LCA model estimates environmental impacts by creating process models and coupling them with life cycle inventory databases, with environmental impacts calculated via the EPA TRACI model.
Initial modeling work to determine the feasibility of integrating guar into the American Southwest has focused on developing process models to quantify the resources required to cultivate guar as well as downstream bioprocessing to obtain guar gum. These models were leveraged to develop a life cycle assessment (LCA) which uses the TRACI 2.1 lifecycle impact assessment (LCIA) method to evaluate environmental impacts. Ongoing work is focused on leveraging the process models to develop a techno-economic assessment integrating farm-level economics and a 30-year discounted cash flow rate of return analysis for a processing facility.
Preliminary results of agricultural modeling show that irrigation and harvesting practices have the highest impact among all TRACI categories. A preliminary sensitivity analysis shows that decreasing the irrigation rate to a minimum value found in literature results in a decrease across all impact categories by over 50%. Results from bioprocessing models have shown that the heating requirements used for guar gum extraction represent the highest bioprocessing energy demand. Modeling results will be used to optimize the overall production of guar gum with experimental work validating models throughout development. Furthermore, the integration of co-products will be investigated, namely the feasibility of obtaining biofuels from residual plant matter. Co-products have the potential to reduce environmental impact and economic costs. Through our analyses, we will determine the environmental impact of cultivating guar in the American Southwest, while considering both the regional and rural economies.
The guayule processing model is a computer model that simulates the operation of a full-scale facility capable of converting guayule into products such as natural rubber and biofuels. This model includes details of industrial equipment such as conveyors, mills, pumps, tanks, and dryers. By including the requirements of each piece of equipment, the model can track the flows of energy, chemical solvents, natural gas, and other resources used within the facility. These flows can then be fed directly into life cycle assessment and techno-economic analysis. The model can run different scenarios and provide a range of possible results to better inform technology development. Additionally, the model can be optimized and adapted to reflect improvements made in the real world.
The research plan for transportation modeling and optimization of feedstock logistics includes the development of system-level models and identification of the optimal strategies or alternatives for production, harvest and collection levels, storage amounts, and transportation routes to meet demands and utilize the resources in economically efficient and environmentally sustainable ways. It bridges the biomass production, processing, and conversion into a whole sustainable bio-economy system, as well as simplifying and streamlining the feedstock logistics. Building on existing research, this project will improve the efficiency of designed algorithms to obtain the solutions for decision-making, increase the quality and accuracy of optimal solutions, enhance the robustness of decisions for biomass supply chain, and ensure the flexibility and adaptability of models for studying in various scales and different regions.
Life Cycle Assessment
Life Cycle Assessment (LCA) quantifies the environmental impact including materials, energy and emissions from raw materials extraction to end of life. LCA can help to identify areas of improvement and compare among different alternatives.
Techno-Economic Analysis (TEA) of a scalable engineering system model for crop bioproduct and biorefinery concepts will insure financial feasibility, while evaluating economic impact to rural communities through input-output methods will assess regional economic impact and sustainability. This all starts with investigation of the appropriate farm level economic analysis necessary to inform the production of guar and guayule in the region. Economic research focuses on securing reliable and authentic data on production practices, yields, costs and prices from published papers and producers to build robust enterprise budgets first for guar and guayule, that will inform farm scenarios developed for New Mexico and Arizona case studies using characteristics such as average farm size, irrigation technology among other unique characteristics of interest.
Progress Made Thus Far
The System Performance and Sustainability Team is driving all aspects of the modeling work forward. Preliminary work has focused on the generation of sub-process models with a current focus on integration across the team. The goal is to have an integrated model that supports the concurrent evaluation of the environmental impact and economic viability of either crop. The following represent achievements thus far:
- Identified the limitations that burden transportation and information for candidate locations for processing facilities; constructed a GIS-based optimization model to minimize the cost from harvest sites to demand destinations;
- LCA process models completed using preliminary data;
- Finalized guayule and guar production cost and prices for robust enterprise budget analysis;
- Completed preliminary farm level assessment of guayule and guar production on employment, labor income, taxes and household spending among other economic indicators;
- Developed a whole farm methodology to accurately evaluate current crop production scenarios, crop production mixes, irrigation, and size (acres farmed) of farmers in Arizona and New Mexico;
- Developed preliminary integration framework to bring all models together for a holistic sustainability assessment; and
- Developed high-fidelity process models for the conversion of both guar and guayule biomass to guar gum and rubber products, respectively.
Research and Results