Report on the Thermochemical Sciences Symposium at Auburn University

November 12, 2018

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by Leyla Battista-Channell* (Advanced Biofuels USA) Auburn, Alabama: Home to the Auburn tigers, the “loveliest village on the plains,” and this year’s host to the Thermochemical Sciences Symposium. Previously held at other universities, why Auburn University this year? The Biosystems Engineering department at Auburn University has been on the rise in the past years, steadily adding new research ventures relating to biomass conversion and pyrolysis. Dr. Sushil Adhikari, a professor in the department conducting thermochemical and biofuels related research, was acting conference chairperson and coordinator for this year’s event.

The conference can be described as diverse, technical, dynamic, and academically focused. The event was divided into two and a half days with lectures, technical sessions, and poster presentations held each day. There were four main focus areas for the conference: lignin, biomass, pyrolysis, and waste utilization.

Lignin and Biomass Utilization

The first day of the conference introduced biomass as a topic by first examining some challenges faced by biorefiners. A major hurdle for biorefiners is the unpredictability surrounding various feedstocks. Currently, there are three main screening methods available. Char measurement is the most rapid of the three, compositional analysis of biomass is more defined but takes longer, and high throughput Py-MBMS to gauge pyrolysis vapor speciation.

The National Renewable Energy Laboratory presented a new study being conducted to tackle this hurdle. The experiment studies 20 different feedstocks in an effort to accelerate screening methods and better anticipate how the treatment processes will be affected.

The plenary sessions started off day two by discussing the fundamentals of lignin and biomass as well as challenges and possibilities for their exploitation.

Lignin

Lignin is one of the most abundant biobased materials in nature. It is also one of the most challenging materials to understand and define. In short, lignin is the part of the plant that gives structure and the component in wood that makes the material hard. Its properties make it ideal for its conventional uses in construction or furniture making. As for its behavior in thermochemical processing, the higher the lignin content of feedstock, the higher the temperatures needed to yield more heavy oils and biochar. The plenary sessions for day two assessed some of the basic procedural outcomes of lignin processing.

Commercial use of lignin is still a challenge due to its mysterious nature, but if utilized correctly, could revolutionize the biofuels and bioenergy industries.

Although optimistic about the future of pyrolysis, the speakers did not attempt to ignore the challenges faced. For instance, difficulties introducing biocrude into refiners, thermal instability, high level of impurities, high acidity, and immiscibility in fossil fuels.

Technical Sessions

With this shared background knowledge, there were many shared goals amongst the researchers; such as improving feed/product characterization and upgrading biocrude refinery integration. After reviewing fundamentals, challenges, and possibilities with all conference attendees, the technical sessions commenced.

Torrefaction

Torrefaction was the topic of conversation for the first technical session on day two. The University of Guelph in Canada is currently studying torrefaction and biomass. Multiple types of biomass and waste are being studied in their experiment: woody biomass, construction waste, agricultural biomass, wet biomass, and purpose grown biomass. The study found that hydrothermal carbonization of fruit wastes resulted in improved fuel quality and higher mass yields due to the higher levels of glucose. While the study did have a positive outcome, the research team concluded that the process would not be competitive on its own.

Guayule and Guar

Characterization and conversion of guayule and guar bagasse was the next topic covered by a research team from New Mexico State University. Guar and guayule are the most prevalent forms of biomass used in the southwestern region of the United States.

Guayule is a highly resilient perennial that has rubber properties. Once processed, guayule biomass yields resin for asphalt, bagasse (used in wood pellets), and a hard rubber that can then be used in tires. Its high lignin content limits access of enzymes to the cellulose, resulting in low alcohol yield.

Similar in its growth requirements, guar thrives in the arid climate of New Mexico. Guar is used to make gaur gum (food additive), animal feed, and as a soil amendment. Both plants are popular forms of biomass for their resiliency and low water requirements. However, further identification and characterization of the plants and their co-products will be needed to make the guar/guayule market viable.

By-products/Co-Products

It is important to note that in the biomass conversion process, there are a number of by-products. To ignore the potential of by-products to also be converted into useful end-products would be an incredible misstep for the scientific community.

The TCS conference speakers did not shy away from this topic. A number of speakers made an effort to consider uses for by-products and were very open to new research undertakings dealing solely in applications of by-products.

In the case of woody biomass, black liquor is a by-product. The University of Zaragoza in Spain is currently experimenting with hydrothermal treatment of black liquor. The outcome of their studying produced a substance capable of being used in the biodiesel production and blending process.

The by-products also move beyond applications in biofuels alone. Guar and guayule by-products are being considered as possible bio-based additives in the cosmeceuticals industry.

Please note that the various projects outlined in the preceding paragraphs only just begin to highlight the incredible work being done by the individuals in attendance. A comprehensive list of speakers and poster presentations may be found at the end of this article.

Pyrolysis

Pyrolysis is a thermochemical process that exposes carbon-based matter to high temperatures in the absence of oxygen. The process ultimately yields high energy content products in the following forms: solid, liquid by-product, and a non-condensable gas.

The conference kicked off with a lecture about the current state of the pyrolysis industry with Art Ragauskas from the University of Tennessee.

Long overlooked due to its perceived youth, pyrolysis is finally coming to be a mature industry. With the ability to now be directly integrated into existing refineries at the front end of the process, pyrolysis could become one of the cheapest options for producing biofuels.

Throughout the first plenary session, a consistent theme was evident: the potential for pyrolysis and all of its various products is infinite.

Technical Sessions

The first technical session concentrated on improving products through advancements in fast pyrolysis and modeling. In fast pyrolysis, organic matter is decomposed in the absence of oxygen at 450-600 centigrade to produce biochar, non-condensable gas, and bio-oil. While not generally required, hydrotreating is used to compensate for the various limitations accompanying fast pyrolysis.

Advanced hydrogen assisted pyrolysis, or hydrous pyrolysis, may effectively address these limitations and produce refinery ready biocrude.

Micro-kinetic modeling was then discussed as a computational method to significantly advance lignin utilization. Kinetic modeling, specifically with regards to autothermal pyrolysis, further offered improved heat transfer for better scalability.

Waste as a Resource

Billions of tons of municipal solid wastes are either sent to landfills or incinerated. MSW, while currently considered a burdensome waste stream, could also be considered a resource for power generation and new jobs.

Unfortunately, this MSW resource is not being utilized well. Since MSW is always changing, technology cannot be particular, making gasification a viable option.

Dr. Ajay Kumar, from Oklahoma State University, presented research findings for his mobile scale power generation with MSW and switchgrass experiment. The goal of the project was to mix MSW and switchgrass and feed the product into a gasifier to produce electrical power and reduce exhaust emissions. The second goal of the project was to fit all of the equipment into the size of a shipping container for greater mobility. Dr. Kumar and his team successfully produced electricity and determined the maximum MSW blend to be 40%.

MSW is not the only under-utilized resource. Food waste is a widespread issue. 45,000 tons of eggshells are disposed of each year in Canada alone. This equates to 40,000 tons of CaCO₃ being wasted. Dr. Animesh Dutta proposed a new outlet for eggshells as a sorbent in chemical looping gasification to enhance carbon negativity.

Conference Summary

While most other technically advanced conferences aim to establish a kind of intellectual exclusivity and formality, the TCS conference deviates from this. The TCS conference somehow managed to maintain a level of advanced technicality while also fostering easy and relaxed dialogue among its attendees.

The TCS conference provides an excellent platform for students, researchers, professors, and companies to come together and discuss interconnected scientific advancements in a welcoming environment.

In addition to the technical sessions, this year’s TCS agenda also included a variety of leisure activities meant to showcase the “local color” in Auburn. Attendees were treated to a reception dinner on the first evening of the event. After the last technical session on day two, an Auburn University wildlife team put on a raptor show for guests. Immediately following the raptor show, a banquet and award ceremony was held at the Auburn Hotel.

After the close of the conference, attendees were also invited on a tour of the gasification and gas-to-liquid laboratory. For those seeking a more intimate and technical conference with a comfortable milieu, look no further than the TCS conference!

*Leyla Battista has a Bachelor’s degree in Biosystems Engineering from Auburn University. She is currently a Master’s candidate in Environmental Sciences at Emory University. For more information on her current and past projects visit her online portfolio at lmb00432.wixsite.com/eportfolio.

Photos by: Ms. Joy Brown and Ms. Amber Denham.

Center for Bioenergy and Bioproducts (Auburn University)

Tags

pyrolysis lignin biomass waste waste-to-chemicals waste-to-fuel cellulose biochar hydrotreating black liquor gasification aromatics torrefaction guar guayule bagasse Alabama thermochemical conversion BioRefineries/Renewable Fuel Production MSW (Municipal Solid Waste) Department of Energy (DOE) Colorado bio-oil/pyrolysis oil Ontario Canada New Mexico co-products Spain Tennessee Biocrude/Green Crude/SynCrude Oklahoma BioChemicals/Renewable Chemicals precursors/biointermediates co-location co-processing Sustainability

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