Download or read book EXPERIMENTAL AND THEORETICAL INVESTIGATION OF SUSTAINABLE FAST PYROLYSIS BIOFUELS FROM WOODY BIOMASS written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Biofuels are an important advancement in alternative energy that can provide substantial environmental benefits compared to their conventional fossil fuel counterparts Said benefits are usually measured using life cycle assessments. However, it is not well understood yet how different methodological choices such as system boundaries, biomass feedstocks, conversion pathways, geographical data, etc. affect the conclusions drawn from biofuels LCA. This research shows large variability in life cycle assessment results and limits comparison across different biofuel pathways due to methodological choices set forth by policy and certification schemes. Advanced biofuels have not reached large scale production due to a limited understanding of thermochemical conversion of various feedstocks and the cost of these feedstocks. To address the issues of feedstock cost, municipal solid waste (MS) was evaluated as a feedstock for the production of bio-oil via fast pyrolysis. MSW (paper waste, grass clippings, fiberboard, waferboard, microllam, plywood) produced similar yields as that of its traditional feedstocks (switchgrass, corn stover and hybrid poplar). Bio-oil yields ranged from 58% to 77% for the MSW feedstocks. The woody waste had the highest yields and the largest production of lignin derived compounds while the paper waste had higher levels of carbohydrate derived compounds and lower yields. To understand how controlled variations in feedstock affected bio-oil speciation, 8 genetically different hybrid poplar samples with increasing lignin content from 17%-22% were pyrolyzed at 500°C, 550°C and 600°C. The purpose of this work was to evaluate how the effect of increasing lignin content with respect to increasing temperature affects product distribution and bio-oil speciation. With increasing lignin content at 500°C the char yield increased from 17.5% to 27.2% and the bio-oil yield decreased from 73% to 65%. With increasing temperature the increase in lignin, allowed for a higher percentage of lignin derived compounds within the bio-oil. To gain a better understanding into biomass degradation, kinetic data was obtained using a micropyrolysis GC/MS experimental set-up. This data was quantified and the mass of bio-oil species produced with respect to time was calculated. The kinetic data showed that hemicellulose derived bio-oil compounds such as acetic acid was produced in large quantities initially, whereas lignin derived compounds such as methyl syringol had a delay in production and took a longer time to reach maximum production. Application of a first order exponential decay model and a six-step degradation model were applied to the data. The first order exponential decay model was insufficient for capturing the initial production of the bio-oil compounds. The six stage degradation model fit the data very well and was able to give insight into biomass degradation with respect to the stoichiometric parameters. These parameters showed that hemicellulose degrades first and then cellulose and lignin degrade at later times agreeing with previous literature. These data along with the application of the six stage degradation model gives a better understanding of biomass degradation with the use of a semi-empirical model. Overall this work shows that MSW and hybrid poplar bio-oil produced via fast pyrolysis are a viable option for the production of biofuels and contributes to the overall knowledge needed for the implementation and advancement within the biofuel industry

Download or read book Sustainable Biorefining of Woody Biomass to Biofuels and Biochemicals written by Deepak Kumar and published by Woodhead Publishing. This book was released on 2023-10-31 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainable Biorefining of Woody Biomass to Biofuels and Biochemicals explores various technologies and pathways for the valorization of woody biomass to produce sustainable biofuels and bioproducts. Focusing on commercialization, the book discusses woody biomass availability, including harvesting, transportation and storage, biomass structure, advanced biorefinery technologies, and the economic and environmental sustainability of woody biomass-based biorefineries. Various technologies are described and assessed from a commercial perspective and practical solutions to the latest challenges are provided. The last section of the book is dedicated to the commercialization aspects of biorefineries, providing details about the techno-economic viability and environmental impact of various biorefinery approaches.This book provides readers with a unique and comprehensive reference that will help students and researchers alike identify and overcome the challenges involved in woody-biomass biorefining for biofuels and biochemicals. It will also be of interest to researchers and professionals involved more broadly in bioenergy and renewable energy, and interdisciplinary teams working across biotechnology, chemistry and chemical engineering, environmental science, and plant sciences. - Presents the fundamental theory and technological details behind woody biomass fractionation in biorefineries, its structure and challenges in its valorization - Focuses on the commercialization aspects of biofuels from woody biomass-based biorefineries - Provides an analysis of the techno-economic viability and environmental impact of various biorefinery approaches - Discusses related policies and regulations

Download or read book Fast Pyrolysis of Biomass written by Robert C Brown and published by Royal Society of Chemistry. This book was released on 2017-06-30 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fast pyrolysis and related catalytic pyrolysis are of increasing interest as pathways to advanced biofuels that closely mimic traditional petroleum products. Research has moved from empirical investigations to more fundamental studies of pyrolysis mechanisms. Theories on the chemical and physical pathways from plant polymers to pyrolysis products have proliferated as a result. This book brings together the latest developments in pyrolysis science and technology. It examines, reviews and challenges the unresolved and sometimes controversial questions about pyrolysis, helping advance the understanding of this important technology and stimulating discussion on the various competing theories of thermal deconstruction of plant polymers. Beginning with an introduction to the biomass-to-biofuels process via fast pyrolysis and catalytic pyrolysis, chapters address prominent questions such as whether free radicals or concerted reactions dominate deconstruction reactions. Finally, the book concludes with an economic analysis of fast pyrolysis versus catalytic pyrolysis. This book will be of interest to advanced students and researchers interested in the science behind renewable fuel technology, and particularly the thermochemical processing of biomass.

Download or read book Production of Biofuels and Chemicals with Pyrolysis written by Zhen Fang and published by Springer Nature. This book was released on 2020-10-27 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a collection of studies on state-of-art techniques for converting biomass to chemical products by means of pyrolysis, which are widely applicable to the valorization of biomass. In addition to discussing the fundamentals and mechanisms for producing bio-oils, chemicals, gases and biochar using pyrolysis, it outlines key reaction parameters and reactor configurations for various types of biomass. Written by leading experts and providing a broad range of perspectives on cutting-edge applications, the book is a comprehensive reference guide for academic researchers and industrial engineers in the fields of natural renewable materials, biorefinery of lignocellulose, biofuels, and environmental engineering, and a valuable resource for university students in the fields of chemical engineering, material science and environmental engineering.

Download or read book Wood Chemistry written by Eero Sjostrom and published by Elsevier. This book was released on 2013-10-22 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wood Chemistry, Fundamentals and Applications, Second Edition, examines the basic principles of wood chemistry and its potential applications to pulping and papermaking, wood and wood waste utilization, pulping by-products for production of chemicals and energy, and biomass conversion.

Download or read book Pyrolysis of Biomass for Fuels and Chemicals written by Akwasi A. Boateng and published by Academic Press. This book was released on 2020-05-27 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pyrolysis of Biomass for Fuels and Chemicals provides a thorough overview of thermochemical conversion of biomass to fuels and chemicals via the pyrolysis platform. The book covers the principles underlying pyrolysis of biomass from the chemical engineering perspective. It discusses thermal-only pyrolysis, the traditional pyrolysis process under inert atmosphere with no catalyst, and the role of catalytic pyrolysis and tail gas reactive pyrolysis in resolving the instability issues associated with product distribution. The addresses condensed phase upgrading where the oil produced can be upgraded for stability or hydrogenated to drop-in transportation fuels, as well as feedstock selection, including opportunity fuels/feedstocks. Finally, pilot and demonstration scale projects from around the world are examined, and some immediate applications of pyrolysis oils in combustion systems are analyzed. Engineering researchers and professionals in the bioenergy, biochemical, and petrochemical fields find in this book a complete resource for understanding the relationships between possible technologies, applications, costs, and products value, as they tackle the challenges for large scale adoption of pyrolysis for the production of 2nd generation biofuels and biochemicals. PhD students in areas of energy, chemical, mechanical, and materials engineering will also benefit from fundamental and applied research in a concise format that can save them time and serve as a reference through bioenergy conversion courses. Covers thermal only pyrolysis, catalytic pyrolysis, and tail gas reactive pyrolysis Examines the relationships between technologies, applications, costs and products value, and end-use Offers a cradle-to-grave approach that includes coverage of feedstocks, their compositional traits, and how they affect conversion technologies with regard to yields, quality of pyrolysis fuel intermediates, and subsequent upgrade to drop-in fuels

Download or read book A Theoretical and Experimental Study on the Pyrolysis of Softwood Sawmill Residues to Py oil written by Sadegh Papari and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pyrolysis oil (py-oil) that is obtained from biomass, through thermochemical conversion in the absence of oxygen, is a possible sustainable source of renewable energy and for useful chemicals. Based on our existing infrastructure which is petroleum-based, py-oil can be an attractive alternative/blend for fossil fuel. The fuel application of py-oil can be limited by high water content, low heating value and high total acid number. Lab-scale and pilot-scale, pyrolysis experiments on forestry residues were performed to determine the impact of key parameters on py-oil yield and properties. The overall objectives of this study were to; determine the important operatorial factors and scale up of the pyrolysis of woody biomass, determine the range of conditions at lab scale for optimal py-oil yield and fuel properties, use these results to optimize the pilot scale auger unit, and develop a process model to simulate the process and be used as a design tool. In Chapter One, an overview on the first and the second generation of pyrolysis, the scopes, the objectives and the significance of this study along with a summary of the thesis chapters was outlined. In Chapter Two, the literature was reviewed to identify the impact of reactor operating conditions on py-oil yield and properties. The results indicated that the key parameters are a faster heating rate and a shorter vapour residence time which produce a higher py-oil yield (up to 75 wt.%) with a higher heating value (up to 22 kJ/kg). In addition, the published empirical and process models for pyrolysis of woody biomass were investigated in order to better understand the applied heat/mass transfer equations, assumptions, kinetic models, and the method of solution. The reported kinetic models in literature were compared with our experimental data obtained from the lab-scale reactor in order to find the -best‖ model. In Chapter Three, the impact of three process parameters including temperature, N2 flow rate, and biomass particle size were investigated on py-oil yield and water content using response surface methodology coupled with central composite design (RSM-CCD) in a lab-scale tube furnace reactor. The results indicated that a 500-550 oC temperature, a 500 mL/min N2 flow rate, and a 0.1-0.5 mm particle size produced the optimum oil for the lab-scale reactor. The quadratic CCD model with factor interactions better predicted the experimental data compared to the quadratic model without parameter interactions. In addition, the results showed that the secondary tar cracking should be included in pyrolysis reactions at a temperature higher than 550 oC, since some condensable organics convert to non-condensable gases by these reactions. After finding the optimum conditions of the lab-scale tube furnace pyrolysis reactor in Chapter Three, the impact of feedstock quality (particle size, moisture content, and age of feedstock) on py-oil yield, higher heating value (HHV), total acid number (TAN), and water content was investigated in the lab-scale reactor (Chapter Four). The results illustrated that the initial moisture content has a little effect on the water chemically produced during pyrolysis. Particle size reduction did not have a significant effect on HHV. The aged feedstock produced a slightly lower py-oil yield and higher water content compared to the fresh feedstock. In addition, a qualitative assessment of the pyrolysis heat of reaction was performed in the lab-scale reactor. The results illustrate the overall endothermic nature of the pyrolysis of this type of biomass (balsam fir wood). This result was helpful in next Chapter (i.e. process modeling). In Chapter Five, a process model was developed for the 2-4 kg/h auger reactor with assuming plug flow model for both solid and gas phases. Process modeling is typically used as a tool in process optimization, scale up, and reactor design to reduce the capital and operating cost of a pyrolysis system. The transport equations for each phase are combined with the kinetic model to predict py-oil, bio-char, and non-condensable gas yields. The process model was validated with the experimental data obtained from this reactor and showed good agreement (with approximately 10% average relative deviation). The model was used to predict py-oil yield as a function of temperature, feed flow rate and reactor pressure. In Chapter Six, the impact of process variables (temperature, feed flow rate, and vacuum fan speed) on py-oil yield, water content, and more importantly phase separation were investigated in the 2-4 kg/h auger reactor. In the optimum conditions (a 450-475 oC temperature, a 2415 rpm vacuum fan speed, and a 4 kg/h feed flow rate) a single phase softwood oil was obtained with 53 wt.% yield and 26 wt.% water content. A comparison between different sawmill residues (softwood shavings, hardwood sawdust, and softwood bark) at similar conditions showed that hardwood and softwood produced a single phase oil with a higher oil yield (53-55 wt.%) and a lower water content (25-26 wt.%) compared to bark (39 wt.% oil yield and a 33 wt.% water content).

Download or read book Encyclopedia of Renewable Energy Sustainability and the Environment written by and published by Elsevier. This book was released on 2024-08-09 with total page 4061 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Renewable Energy, Sustainability and the Environment, Four Volume Set comprehensively covers all renewable energy resources, including wind, solar, hydro, biomass, geothermal energy, and nuclear power, to name a few. In addition to covering the breadth of renewable energy resources at a fundamental level, this encyclopedia delves into the utilization and ideal applications of each resource and assesses them from environmental, economic, and policy standpoints. This book will serve as an ideal introduction to any renewable energy source for students, while also allowing them to learn about a topic in more depth and explore related topics, all in a single resource.Instructors, researchers, and industry professionals will also benefit from this comprehensive reference. - Covers all renewable energy technologies in one comprehensive resource - Details renewable energies' processes, from production to utilization in a single encyclopedia - Organizes topics into concise, consistently formatted chapters, perfect for readers who are new to the field - Assesses economic challenges faced to implement each type of renewable energy - Addresses the challenges of replacing fossil fuels with renewables and covers the environmental impacts of each renewable energy

Download or read book Pyrolysis of Biomass written by Shurong Wang and published by Walter de Gruyter GmbH & Co KG. This book was released on 2016-12-05 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the development of societies fossil energy is no longer the only energy resource, and increasing attention had been paid to alternative energy. Biomass is considered to be one of the alternatives due to efficiency and low cost. This book presents biomass pyrolysis behavior for three main components: Cellulose, Hemicellulose and Lignin, and discusses the influence of mineral salts , zeolite catalysts and metal oxide on their pyrolysis.

Download or read book Innovative Solutions in Fluid Particle Systems and Renewable Energy Management written by Tannous, Katia and published by IGI Global. This book was released on 2015-07-01 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: The threat of natural resource depletion due to high energy demands has become a key concern in both the developed and developing worlds. To alleviate these concerns, researchers around the world are exploring sustainable methods for generating energy. Innovative Solutions in Fluid-Particle Systems and Renewable Energy Management presents phenomenological, experimental, and theoretical research, as well as market criteria and business models concerning the development of small- and large-scale chemical and energy plants. Associating academic and industrial experiences, this book highlights current topics in sustainable energy management and development with an emphasis on obtaining liquid, gaseous, and solid fuels using residues and energetic biomasses. Academicians, researchers, and technology developers will find this book useful in furthering their own knowledge and research in this field. A pivotal publication in the field of engineering, this title covers a range of topics including, among others, cellulosic feedstock, agricultural biomass, fluid dynamics, gasification processes, energy extraction from raw materials, and environmental sustainability.

Download or read book Sustainable Valorization of Agriculture Food Waste Biomass written by Dan Bahadur Pal and published by Springer Nature. This book was released on 2023-07-31 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edited book focuses on agricultural and food waste biomass valorization in various fields such as energy and environment and the development of several other value-added products. The chapters in this book cover different areas like sources of agricultural and food wastes, recent trends on waste utilization, innovations and sustainability of techniques, and challenges associated with valorization of wastes. In the last few decades, scientists and researchers of different countries predicted that waste material generated due to global problems can be used as a potential feeding material for the manufacturing of different valuable products. Hence, there is a need for more research and development of several other value-added products from waste materials. Proper utilization of these waste materials has been discussed in this book. It also covers the bioactive recovery from food waste, health benefits of extracted bioactive, and utilization of valorized products. The book also explores future technological challenges and sustainability issues. This title is a great resource for environmental and chemical engineers, food scientists, food researchers and technologists, as well as for students and professionals working in this field.

Download or read book Biomass Processing for Biofuels Bioenergy and Chemicals written by Wei-Hsin Chen and published by MDPI. This book was released on 2020-05-23 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biomass can be used to produce renewable electricity, thermal energy, transportation fuels (biofuels), and high-value functional chemicals. As an energy source, biomass can be used either directly via combustion to produce heat or indirectly after it is converted to one of many forms of bioenergy and biofuel via thermochemical or biochemical pathways. The conversion of biomass can be achieved using various advanced methods, which are broadly classified into thermochemical conversion, biochemical conversion, electrochemical conversion, and so on. Advanced development technologies and processes are able to convert biomass into alternative energy sources in solid (e.g., charcoal, biochar, and RDF), liquid (biodiesel, algae biofuel, bioethanol, and pyrolysis and liquefaction bio-oils), and gaseous (e.g., biogas, syngas, and biohydrogen) forms. Because of the merits of biomass energy for environmental sustainability, biofuel and bioenergy technologies play a crucial role in renewable energy development and the replacement of chemicals by highly functional biomass. This book provides a comprehensive overview and in-depth technical research addressing recent progress in biomass conversion processes. It also covers studies on advanced techniques and methods for bioenergy and biofuel production.

Download or read book An Investigation of the Kinetics for the Fast Pyrolysis of Loblolly Pine Woody Biomass written by Alexander W. Williams and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the search for fossil fuel alternatives the production of bio-oil through the pyrolysis of biomass is one method which has shown evidence of scalability, meaning that the technology could be scaled up for the processing of biomass on the order of tons per day. Pyrolysis is the thermal degradation of compounds in the absence of oxygen. Of particular interest is the pyrolysis of sustainable energy crops such as Loblolly pine (Pinus taeda). The goal of this study is to develop a new method of characterizing the fast pyrolysis of biomass for the advancement of reactor design. The objectives are to determine bulk kinetic coefficients for the isothermal fast pyrolysis of biomass, evaluate the interchangeability of fast and slow pyrolysis kinetic parameters and compare generally accepted pyrolysis mechanisms derived from a common data set. A technical objective is to apply the most suitable derived kinetic parameters to model pyrolysis within a moving bed reactor.

Download or read book Handbook of Biomass Valorization for Industrial Applications written by Shahid ul-Islam and published by John Wiley & Sons. This book was released on 2022-01-05 with total page 555 pages. Available in PDF, EPUB and Kindle. Book excerpt: HANDBOOK of BIOMASS VALORIZATION for INDUSTRIAL APPLICATIONS The handbook provides a comprehensive view of cutting-edge research on biomass valorization, from advanced fabrication methodologies through useful derived materials, to current and potential application sectors. Industrial sectors, such as food, textiles, petrochemicals and pharmaceuticals, generate massive amounts of waste each year, the disposal of which has become a major issue worldwide. As a result, implementing a circular economy that employs sustainable practices in waste management is critical for any industry. Moreover, fossil fuels, which are the primary sources of fuel in the transportation sector, are also being rapidly depleted at an alarming rate. Therefore, to combat these global issues without increasing our carbon footprint, we must look for renewable resources to produce chemicals and biomaterials. In that context, agricultural waste materials are gaining popularity as cost-effective and abundantly available alternatives to fossil resources for the production of a variety of value-added products, including renewable fuels, fuel components, and fuel additives. Handbook of Biomass Valorization for Industrial Applications investigates current and emerging feedstocks, as well as provides in-depth technical information on advanced catalytic processes and technologies that enable the development of all possible alternative energy sources. The 22 chapters of this book comprehensively cover the valorization of agricultural wastes and their various uses in value-added applications like energy, biofuels, fertilizers, and wastewater treatment. Audience The book is intended for a very broad audience working in the fields of materials sciences, chemical engineering, nanotechnology, energy, environment, chemistry, etc. This book will be an invaluable reference source for the libraries in universities and industrial institutions, government and independent institutes, individual research groups, and scientists working in the field of valorization of biomass.

Download or read book TECHNO ECONOMIC AND LIFE CYCLE ASSESSMENTS OF BIOFUEL PRODUCTION FROM WOODY BIOMASS THROUGH TORREFACTION FAST PYROLYSIS AND CATALYTIC UPGRADING written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Biofuel production through fast pyrolysis of biomass is a promising conversion route in the production of biofuels compatible with existing technology. The bio-oil produced from fast pyrolysis is a versatile feedstock that can be used as a heating oil or upgraded to a transportation hydrocarbon biofuel. Comparative study of a one-step, fast pyrolysis only pathway and a two-step torrefaction-fast pyrolysis pathway was carried out to evaluate the effect of torrefcation on (i) the minimum selling price of biofuel and (ii) the potential life cycle GHG emissions of the biofuel production pathway. To produce bio-oil which can serve as a substitute for heating oil from loblolly pine biomass feedstock, torrefaction at three different temperatures of 290, 310 and 330°C were investigated while fast pyrolysis occurred at 530°C. Three scenarios of producing process heat from natural gas, internal by-products biochar or torrefaction condensate were also investigated. Economic assessment showed more favorable economics for the two-step bio-oil production pathway relative to the one-step bio-oil production pathway. The lowest minimum selling price of $1.04/gal was obtained for a two-step pathway with torrefaction taking place at 330°C. The environmental impact assessment also showed more the two-step bio-oil production pathway to be more environmentally friendly. The lowest GWP of about -60g CO2eq was observed for the two-step pathway at torrefaction temperature of 330°C while GWP of about 36g CO2eq was observed for the one-step pathway. Relative to heavy fuel oil, the one-step and two-step pathways are more environmentally friendly with lower GWP. To produce hydrocarbon biofuel by the catalytic upgrade of bio-oil derived from fast pyrolysis of loblolly pine, three torrefaction temperatures of 290, 310 and 330°C were investigated with fast pyrolysis taking place at 530°C. Three scenarios of producing process heat from natural gas, internal by-products biochar or torrefaction condensate were investigated. The effect of heat integration was also examined. The economic assessment showed equal minimum selling price for the one-step hydrocarbon biofuel production pathway and a two-step pathway with torrefaction occurring at 290°C. A minimum selling price of $4.82/gal was estimated while higher torrefaction temperatures showed less favorable economics. The environmental impact assessment however showed the two-step pathway to be more environmentally friendly when compared with the one-step pathway. GWP of about -66g CO2eq was observed for the two-step pathway with torrefaction taking place at 330°C compared to a GWP of about 88g CO2eq obtained for the one-step. Further reduction in minimum selling price and GWP were observed with heat integration. A minimum selling price of about $4.01/gal was estimated for the one-step and two-step pathway with torrefaction taking place at 290°C while GWP of about -144 g CO2eq was observed for the two-step hydrocarbon biofuel with torrefaction temperature of 330°C.

Download or read book An Experimental Investigation Into Fast Pyrolysis of Biomass Using an Entrained flow Reactor written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Biochar As A Renewable based Material With Applications In Agriculture The Environment And Energy written by Joan J Manya and published by World Scientific. This book was released on 2020-08-14 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biochar and its implementation as a renewable-based material is one of the topics on which the research community has focused the greatest energy in the last twenty years. This book provides readers with a scientific and technological overview of biochar, including new technologies for biochar production, new environmental and agronomic applications (e.g. biochar as growing media component or biochar application for mine land reclamation) and some emerging biochar applications in different fields (e.g. energy storage and catalysis). A special emphasis is placed on analyzing the links between the different stages of the value chain, underpinning the economic viability of biochar systems.Biochar as a Renewable-Based Material: With Applications in Agriculture, the Environment and Energy is designed as a textbook for graduate and postgraduate courses as well as a handbook for early-stage scientists, policy makers and potential technology customers. The book is written by internationally recognized scientists with a variety of complementary backgrounds.