Renewable Energy Global Innovations features: A techno-economic comparison of Fischer–Tropsch and fast pyrolysis as ways of utilizing sugar cane bagasse in transportation fuels production

Significance Statement

In recent years, critical issues such as energy security, petrol price upsurge and increasing consciousness of global warming, have all garnered attention from all walks of life to focus on the prospects of a bioenergy sector. The concept of biorefinery has recently emerged where biomass has already been identified as the sole source of renewable energy which has properties similar to fossil fuels. Sugarcane is currently the most cost-effective feedstock for the biofuel production and could become even cheaper and more advantageous if the waste bagasse would also be converted to biofuels. From various technoeconomic analysis, two techniques: the fast pyrolysis-hydro processing route and gasification coupled with Fischer–Tropsch synthesis, have been considered to be feasible for application in the large-scale production of bio fuels from the sugarcane bagasse.

In a recent paper published in Chemical Engineering Research and Design Stavros Michailos and Colin Webb from the School of Chemical Engineering and Analytical Science at University of Manchester in collaboration with David Parker at University of Exeter compared the economic and technological feasibility of the fast pyrolysis-hydro processing route (repurposed to enhance hydrogen production) and gasification coupled with Fischer–Tropsch synthesis processes. They aimed at resolving which between the two processes would deliver final products of fuels that can be directly used within the inherent technological infrastructure cheaply.

The adaptability of gasification followed by Fischer–Tropsch synthesis and fast pyrolysis coupled with hydro processing were examined against economic and thermodynamic criteria. Sugarcane bagasse was adopted as the feedstock at a flow rate of 100 metric tonnes per hour. The research team then utilized the Aspen plus process simulation software to build robust and thermodynamically rigorous simulations of the constituent processes of these biofuel conversion options processes. Mass, energy balance of the constituent processes, the overall thermochemical energy and economic efficiencies were calculated for each option based on the quantification and assessment of the yield.

From the comparative analysis of two near term biomass-to-liquid fuels conversion options, the researchers observed that the higher fuels productivity associated with the Fischer–Tropsch process resulted in in higher thermodynamic efficiencies than fast pyrolysis process. During fast pyrolysis, lignin is exploited in a steam cycle to generate electricity while in Fischer–Tropsch process, lignin is gasified and thereby it contributes to liquid fuels production. Moreover, almost forty percent of electricity generated by fast pyrolysis CHP unit is utilized to compress hydrogen. According to economic assessment Fischer–Tropsch process outplays fast pyrolysis process achieving higher values for all economic indicators. In addition, it is more lenient to variations of the elementary financial specifications. Conversely, the fast pyrolysis process delivers higher product diversity.

In light of the aforementioned remarks and outcomes, the choice of the best alternative conversion route depends on many aspects including factors aside from those enumerated in this study, such as market demand and location of the plant. However, at the moment and solely based on thermo-economic criteria Fischer–Tropsch process is more efficient than fast pyrolysis process mainly due to higher thermodynamic performance, minimal risk and substantial economic returns.

Reference

Stavros Michailos¹, David Parker², Colin Webb¹. A techno-economic comparison of Fischer–Tropsch and fast pyrolysis as ways of utilizing sugar cane bagasse in transportation fuels production. Chemical Engineering Research and Design. Volume 118 (2017) pages 206–214.

Show Affiliations

1. School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
2. School of Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK

 

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Renewable Energy Global Innovations features: Development of La(Cr,Co,Fe,Ni)O3 system perovskites as interconnect and cathode materials for solid oxide fuel cells

Significance Statement

Due to an increase in demand for sustainable energy sources, solid oxide fuel cells (SOFCs) have received more attention owing to their huge potential for power production in portal transport applications. Almost all solid oxide fuel cells are arranged either in parallel or series in order to facilitate voltage output. An interconnect is needed to connect the cells. It connects the cathode of one cell to the anode of the other, yet physically separates the cells.

An interconnect should be non-porous with 100% relative density to avoid the mixing of fuel and oxygen. Above all, it must be stable in oxidizing and reducing environments, have high electrical conductivity, chemical stability and sintering attributes. It can be metallic or ceramic. One desirable material for a ceramic interconnect in solid oxide fuel cell is the doped Lanthanum Chromite based perovskite material.

The cathode material should as well meet stringent requirements. Therefore, the shortcomings in perovskite oxide materials adopted for cathode and interconnect fabrication can be overcome through the synthesis of new materials by adding or modifying the transition metals in the current materials to enhance chemical stability, low sintering temperature, electronic and ionic conductivity, and thermal expansion coefficient.

Researchers led by Professor Rasit Koc at Southern Illinois University developed cathode and interconnect material for solid oxide fuel cells. Their main aim was to develop and evaluate cathode and interconnect materials for SOFC which will meet the exacting requirements of SOFC manufacturers.  These requirements are fabricability (sinterability) at temperatures 1400^oC and below at lower cost, high electronic conductivity, chemical stability in reducing and oxidizing conditions and coefficient of thermal expansion match with other cell components.  Dr. Zhezhen Fu of University of Maryland says “The developed sinterable materials with very high electrical conductivity are critical in the commercialization of low temperature solid oxide fuel cells (LT-SOFCs)”. The research work on La(Cr,Co,Fe,Ni)O₃ is now published in Ceramics International.

The authors prepared the powders through the Pechini approach. They mixed metal nitrates and lanthanum carbonate as starting materials in stoichiometric proportions. The resulting mixture was then mixed with ethylene glycol and citric acid forming a polymer that broke to form powder precursor. The precursors were calcined, ball milled, and pressed to form circular pellets. The microstructure developed completely in the course of the sintering process. The sintered samples were polished and thermally etched for microstructure analysis.

samples were prepared for electrical conductivity measurement. Each sample was subjected to resistance measurements. The pellets were then heated in a furnace and resistance measured as a function of temperature in the range of solid oxide fuel cell operation.

Through the Pechini polymer complexing approach, the authors were able to synthesize five compounds into a single phase of LaCo_0.7Cr_0.1Fe_0.1Ni_0.1O₃ (LCo7CFN), LaNi_0.7Cr_0.1Co_0.1Fe_0.1O₃ (LNi7CCF), and LaCr_0.25Co_0.25Fe_0.25Ni_0.25O₃ (LCCFN), LaFe_0.7Cr_0.1Co_0.1Ni_0.1O₃ (LFe7CCN), were sintered to a relative density of 98%, 82%, 94%, and 91% respectively at about 1400 °C for two hours in air. Transit liquid phases formed under the sintering conditions and contributed to the high relative densities. LaCr_0.25Co_0.25Fe_0.25Ni_0.25O₃ (LCCFN), posted the highest electrical conductivity.

Among the lanthanum perovskite oxides, LaCo_0.7Cr_0.1Fe_0.1Ni_0.1O₃ (LCo7CFN) and LaCr_0.25Co_0.25Fe_0.25Ni_0.25O₃ (LCCFN) appeared to comprise building blocks for interconnect fabrication owing to their high relative densities (94-98 %) and excellent electrical conductivity (>50 S/cm). LaNi_0.7Cr_0.1Co_0.1Fe_0.1O₃ (LNi7CCF) with high electrical conductivity and relative density of approximately 82% was selected to be a suitable candidate for the porous cathode.  Currently, these materials are being doped with Ca on the La site to further enhance their properties.

About The Author

Abhigna Kolisetty graduated from Southern Illinois University Carbondale with a Master’s degree in Mechanical Engineering. Her research interests are Material Science, clean energy, energy conservation, and energy efficiency. Under the guidance of her advisor, Dr Rasit Koc, Abhigna worked on developing interconnect and cathode materials for Solid Oxide Fuel Cells as her thesis topic. This research has been published in the journal “Ceramics International” as the article, “Development of La(CrCoFeNi)O₃ system perovskites as interconnect and cathode materials for solid oxide fuel cells.” She is currently a Mechanical Designer for AECOM, an engineering consulting firm in Cleveland, Ohio.

 

About The Author

Zhezhen Fu received his Ph.D. degree from Southern Illinois University in 2016. He is currently a Postdoctoral Associate at the University of Maryland. His research focuses on the processing and characterization of advanced ceramic materials such as: (1) titanium carbide and boride materials for structural application; (2) doped LaCrO3 perovskite for solid oxide fuel cell application; (3) lithium-ion conducting garnet-oxide for all-solid-state battery application.

About The Author

Dr. Rasit Koc is a Professor and Chair of Mechanical Engineering and Energy Processes (MEEP) Department at SIUC. Before coming to SIUC, Dr. Koc was a Senior Engineer at U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) in Golden, Colorado, where he conducted research in the areas of Processing and Characterization of Advanced Ceramic Materials and Composites. In 1995, his work on synthesizing nano-size SiC materials received R&D 100 award. During his graduate studies, he worked in cooperation with Dr. Harlan U. Anderson, in the areas of ceramic materials for Fuel Cells. Koc has authored/coauthored more than 100 papers and holds 3 U.S. patents. He served as the American Ceramic Society Rocky Mountain Chapter treasurer and he was an associate editor of the journal for 12 years.

Reference

Abhigna Kolisetty, Zhezhen Fu, and Rasit Koc. Development of La(Cr,Co,Fe,Ni)O₃ system perovskites as interconnect and cathode materials for solid oxide fuel cells. Ceramics International, volume 43 (2017), pages 7647–7652.

Department of Mechanical Engineering and Energy Processes, Southern Illinois University, 1230 Lincoln Drive, Carbondale, IL 62901, United States.

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Renewable Energy Global Innovations features: Preferential positioning and phase exposure of granular particles at hydrophobic liquid-water interface

Significance Statement

Granular materials such as limestone and sand have been observed to exhibit an aptitude to aggregate with a hydrophobic phase, such as oil, thereby capturing substantial amounts of oil that floats on water surfaces. This unique phenomenon of selective positioning of the granular materials at the non-colloidal scale at the hydrophobic liquid-water interfaces is yet to be exhaustively studied and reported in the existing scientific literature. Consequently, it has therefore attracted profound interest as the comprehension of the granular particle behavior is needed for the possibility of utilizing readily available granular materials for capturing oil and curbing the mobility of floating oils as a treatment method.

In a recent paper published in Journal of Cleaner Production Daria Boglaienko and Berrin Tansel from the Department of Civil and Environmental Engineering at Florida International University proposed to analyze the observed variations in the positioning and behavior of the natural granular particles of limestone and quartz at the hydrophobic liquid-water interfaces. They also aimed at evaluating the dominant force impact on the particles behavior.

Foremost, experiments were carried out using dyed quartz and limestone particles with a 0.2-millimeter diameter for the fine particles and 0.5 millimeter for the medium sized particles. The researchers then used particles of different colors so that positioning of the particles with different sizes could be visually observed in the hydrophobic liquid water systems. They then selected silicon oil, tetradecane and crude oil for use as the hydrophobic liquid. Eventually, the researchers analyzed the behavior of the particles at the hydrophobic liquid and water interfaces through the application of the electrostatic image force theory.

By comparing theoretical and empirical results obtained, the researchers observed that the theoretical results did not support the assumption that the particle positioning at the liquid interface can be theoretically linked to gravitational force. The limestone which has active surface properties was observed to possess higher surface charge hence was able to cross the tetradecane-water interface abandoning the non-reactive tetradecane phase. They also observed that the zeta potentials of the aqueous limestone decreased upon addition of crude oil which explains why the limestone particles were held at the crude oil-water interface. These helped them conclude that the polar fractions of crude oil affected the surface charge and zeta potential of a particle.

The empirical observations have directed that the effects of the charge differences are more significant than the effect of the size difference in determining the position of a particle in a hydrophobic liquid, hydrophobic liquid-water interface and water phase. It is therefore important to note that slight differences in material composition affects surface characteristics thereby resulting in differences in the preferential positioning of the particles. The phenomenon presented here is of high interest and presents a new oil spills treatment technique which is inexpensive, simple and environmentally friendly.

About The Author

Dr. Berrin Tansel is a professor in the Civil and Environmental Engineering Department at Florida International University (FIU). She has over 30 years of experience in environmental engineering, water quality management, physical-chemical treatment methods, contaminant-surface interactions and water infrastructure. She has received her PhD degree in environmental engineering from University of Wisconsin-Madison.

Dr. Tansel is an elected Fellow of the American Society of Civil Engineers (ASCE) and Environmental and Water Resources Institute (EWRI). She is a Diplomate of American Academy of Water Resources Engineers, and Board Certified Environmental Engineer by the American Academy of Environmental Engineers. She is a registered professional engineer in the State of Florida, USA. She has published over 200 journal papers, book chapters, technical reports and two books. Dr. Tansel is the editor in chief of the Journal of Environmental Management.

About The Author

Daria Boglaienko received her PhD in Civil Engineering (with specialization in Environmental), Florida International University. She holds two Master’s Degrees: from National Technical University in Ukraine and from Florida International University, where she got Outstanding academic achievement award. Her overall research experience can be characterized as one with a broad interdisciplinary focus. She studied benefits of alternative energy sources with a specialization on biogas production in waste treatment and anaerobic digestion processes. For her second master’s thesis she integrated several important aspects of a cover crop study to clarify mycorrhizal status of a plant, to investigate the benefits after its incorporation into soil, and to assess and prove its economic value.

Daria’s dissertation research was on floating crude oil capture and encapsulation using granular materials. She analyzed oil-particle aggregation from different perspectives, proposing and developing recommendations for a new environmentally friendly and inexpensive method to capture floating oils. Daria received Outstanding doctoral award in Civil Engineering and Worlds Ahead Graduate award from Florida International University.

Reference

Daria Boglaienko, Berrin Tansel. Preferential positioning and phase exposure of granular particles at hydrophobic liquid-water interface. Journal of Cleaner Production volume 142 (2017) pages 2629-2636.

Department of Civil and Environmental Engineering, Florida International University, Miami, FL, USA.

 

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