• Energy Research

Abstract Bioproducts from biomass feedstocks and organic wastes have shown great potential to address challenges across food-energy-water systems. However, bioproducts production is at an early, nascent stage that requires new inventions and cost-reducing approaches to meet market needs. Biochar, a byproduct of the pyrolysis process, derived from nutrient-rich biomass feedstocks (e.g., cattle manure and poultry litter) is one of these bioproducts that has numerous applications, such as improving soil fertility and crop productivity. This study investigates the market opportunity and sustainability benefits of converting manure to biochar on-site, using a portable refinery unit. Techno-economic and environmental impact assessments are conducted on a real case study in Twin Falls, Idaho, USA. The techno-economic analysis includes a stochastic optimization model to calculate the total cost of biochar production and distribution. The environmental study employs a life cycle assessment method to evaluate the global warming potential of manure-to-biochar production and distribution network. The total cost of biochar production from cattle manure near the feedlots is approximately $237 per metric ton, and total emission is 951 kg CO2 eq. per metric ton. The on-site operation and manure moisture content are two key parameters that can reduce biochar unit price and carbon footprint of manure management. It is concluded that converting cattle manure, using the presented strategy and process near the collection sites can address upstream and midstream sustainability challenges and stimulate the biochar industry.

Abstract Bioenergy sources have been introduced as a means to address challenges of conventional energy sources. The uncertainties of supply-side (upstream) externalities (e.g., collection and logistics) represent the key challenges in bioenergy supply chains and lead to reduce cross-cutting sustainability benefits. We propose a mixed biomass-based energy supply chain (consisting of mixed-mode bio-refineries and mixed-pathway transportation) and a multi-criteria decision making framework to address the upstream challenges. Our developed framework supports decisions influencing the economic and environmental dimensions of sustainability. Economic analysis employs a support vector machine technique, to predict the pattern of uncertainty parameters, and a stochastic optimization model, to incorporate uncertainties into the model. The stochastic model minimizes the total annual cost of the proposed mixed supply chain network by using a genetic algorithm. Environmental impact analysis employs life cycle assessment to evaluate the global warming potential of the cost-effective supply chain network. Our presented approach is capable of enhancing sustainability benefits of bioenergy industry infrastructure. A case study for the Pacific Northwest is used to demonstrate the application of the methodology and to verify the models. The results indicate that mixed supply chains can improve sustainability performance over traditional supply infrastructures by reducing costs (up to 24%) and environmental impacts (up to 5%).

Abstract Recent interest in reducing stress on the food-energy-water (FEW) nexus requires the use of renewable, organic products that can subsequently address environmental sustainability concerns, such as mitigating greenhouse gas emissions. Pyrolysis-derived biochar from organic wastes (e.g., nutrient-rich agricultural wastes and leftovers, forest harvest residues, and cattle manure) and advanced feedstocks (e.g., algae) is capable of addressing ever-increasing global FEW concerns. Biochar water-nutrient holding capacity and carbon sequestration are key attributes for improving organic farming and irrigation management. The major challenge to commercialize biochar production from organic wastes is the conversion process. Pyrolysis process is a cost-effective and successful approach in comparison to other conversion technologies (e.g., gasification) due to low energy requirement and capital cost, as well as high process efficiency and biochar quality. To determine the environmental impacts of the biochar production process, an analysis of the material, energy, and emission flows of a small-scale pyrolysis process is conducted for a real case study, using life cycle assessment method with the assistance of available life cycle inventory databases within OpenLCA software. The results demonstrate that this study is able to enhance sustainability aspects across FEW systems by (a) employing a portable refinery to address upstream challenges (i.e., collection, transportation, and preprocessing) of waste-to-biochar life cycle, (b) recycling domestic forest and agricultural residues (e.g., pine wood), (c) producing organic biochar-derived soil conditioners that can improve organic cropping and FEW systems. Ultimately, we conclude by discussing techno-economic and socio-environmental implications of biochar production from organic wastes and advanced feedstocks.

Abstract Value-added products from petroleum-based wastes (e.g., mixed plastics) have shown great potential to address sustainability challenges, such as global waste management and environmental pollution from petroleum-based products. However, recycling mixed plastic wastes (MPW) has been debated for producing renewable materials and value-added products, such as C10-C50 liquid hydrocarbon compounds. This study investigates the economic feasibility and sustainability benefits of producing MPW pyrolysis oil (p-oil), using a transportable refinery unit. The presented approach was evaluated by conducting a case study in southeast Idaho, USA. A multi-criteria decision-making model consisting of techno-economic analysis and life cycle assessment is utilized to evaluate the proposed pathway. The techno-economic analysis estimates the total cost of MPW to value added products supply chains. The life cycle assessment (LCA) evaluates the negative environmental impacts of MPW-to-products life cycle. LCA assesses the global warming potential for a 100-year time horizon. The p-oil production cost per metric ton is $228, while the total emission is 2,262 kg CO2 per 100 metric tons of MPW. The results indicate that on-site operation can reduce MPW management and carbon footprint. Based on the results, MPW conversion to liquid hydrocarbon products using the mobile pyrolysis conversion process can address the supply chain sustainability challenges and lead to sustainable production.

Abstract Growing consumption of rare earth elements (REEs) due to their critical roles in various sectors (e.g., healthcare, energy, transportation, and electronics) has gained attention and stimulated research efforts in industry and academic communities. This study provides an overview of the existing REE production and recovery pathways, identifies critical challenges of the current techniques, and highlights opportunities for multidisciplinary research to achieve more effective solutions. A comprehensive classification of REE separation techniques is presented through narrative and systematic literature reviews, including qualitative analysis and classic bibliometric techniques, to assess the usefulness of identified methodologies and approaches. It is found that the top three most explored and mature separation techniques in various phases (solid and liquid) between 2015 and 2020 are leaching, solvent extraction, and plasma; and the top three study fields are chemistry, engineering, and metallurgy. It is further found that the dominant REE separation technique across over 40 fields of research is the use of acids, bases, ionic liquids, and salts for leaching REEs. It is concluded that agromining approach, using hyperaccumulator plants capable of absorbing REEs through their roots and leaves, can be a practical approach for sustainable REEs recovery from secondary sources and end-of-life products, such as electronic devices.

Abstract Bioenergy sources are being advanced as a meaningful environmental solution and a substitute for conventional energy sources. Bioenergy from biomass feedstocks currently comprises the largest portion of renewables in the United States. Thus, more effective process-level solutions can result in scaling-up biomass-derived energy production (e.g., biofuels). Pyrolysis, a thermochemical conversion technology, offers a commercially viable pathway to produce bio-oil from a wide range of biomass feedstocks (e.g., algae and terrestrial). Bio-oil requires further upgrading to produce final bioproducts (e.g., transportation fuels and biochemicals). This article focuses on the upgrading of bio-oil to transportation fuels (liquid hydrocarbons), highlights the critical challenges of existing upgrading technologies, and identifies the potential research directions to meet the market needs. A comprehensive overview and classification of bio-oil upgrading pathways and their competencies are presented through both comparative and systematic literature reviews. It is concluded that the biofuel production cost is highly dependent on post-conversion pathways, particularly their hydrogenation and deoxygenation capacity. Thermochemical treatments are effective, but less cost-competitive due to the intensive process requirements (e.g., heat or pressure). Biochemical treatments are inadequate as a standalone process for upgrading bio-oil. Physicochemical treatments are less effective, however, they operate under mild process conditions and could be integrated with other treatments. It is further concluded that the electrochemical approach can be effective due to the retention of hydrogen from bio-oil water content during deoxygenation.

AbstractRecent interest in improving pedagogical approaches in science, technology, engineering, and mathematics (STEM) fields has stimulated research at many universities. Several educational methodologies are reviewed in the context of manufacturing and through the lens of sustainability. It is found that there is a need to identify and understand the STEM educational challenges, and to assess the usefulness of existing methodologies using case-based analyses. In particular, this research aims to support student learning in manufacturing engineering through real-time process evaluations. A pedagogical framework is presented that can assist engineering educators in developing learning modules in support of this goal. The framework encompasses four steps: define the learning outcomes, create instructional resources, create active learning resources, and create a summative assessment mechanism. The framework emphasizes engagement of manufacturing engineering students in psychomotor learning, which remains a challenge due to the high cost of instructional laboratories. The framework is applied to develop a participatory pedagogy for manufacturing courses through the use of computer numerical control of manufacturing operations, and real-time monitoring, visualization, and data analysis of machine energy use. The framework is demonstrated for upper-level undergraduate and graduate manufacturing engineering courses at two universities (i.e., Computer-Aided Design and Manufacturing at Oregon State University and Precision Manufacturing at University of California, Berkeley). It is found that the framework can effectively support learning module development in manufacturing engineering education.

Abstract Global demand for transportation fuels is projected to increase 40% by 2040, and biomass-derived fuels (biofuels) play a crucial role in substituting fossil fuels and mitigating greenhouse gas emissions. Currently, biofuels are mainly consumed as blendstocks combined with petroleum-based fuels, and effective conversion technologies can address the quality challenges for offering standalone biofuels. Thermochemical conversion process is one of the most promising pathways among existing technologies for biofuel production. However, the major barriers are unwanted characteristics (e.g., thermal instability) of intermediate products, such as bio-oil, and required upgrading treatments for producing compatible fuels. This study highlights the merits and critical challenges of thermochemical conversion and physicochemical upgrading technologies for bio-blendstock production from lignocellulosic biomass. The novelty of this study lies in potential directions for future research through both critical and systematic literature reviews, and the proposed intensified process for lignocellulosic-based fuel blendstocks production. It is concluded that recovery and fractionation strategies (e.g., quenching and stripping) can maximize process yields and add values in the efficient conversion pathways. Effective quenching can stop secondary free radical reactions and improve liquid yields over gas and solid yields. Stripping process can improve process yield, catalyst lifespan, and thermal stability. It is further concluded that physicochemical treatments are not as effective as thermochemical treatments, but have advantages of mild operating conditions and potential for integrated solutions in conjunction with other treatments.