Biorefinery Production Technologies for Chemicals and Energy E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 853

Veröffentlichungsjahr: 2020

Beschreibung

This book covers almost all of the diverse aspects of utilizing lignocellulosic biomass for valuable biorefinery product development of chemicals, alternative fuels and energy. The world has shifted towards sustainable development for the generation of energy and industrially valuable chemicals. Biorefinery plays an important role in the integration of conversion process with high-end equipment facilities for the generation of energy, fuels and chemicals. The book is divided into four parts. The first part, "Basic Principles of Biorefinery," covers the concept of biorefinery, its application in industrial bioprocessing, the utilization of biomass for biorefinery application, and its future prospects and economic performance. The second part, "Biorefinery for Production of Chemicals," covers the production of bioactive compounds, gallic acid, C4, C5, and C6 compounds, etc., from a variety of substrates. The third part, "Biorefinery for Production of Alternative Fuel and Energy," covers sustainable production of bioethanol, biodiesel, and biogas from different types of substrates. The last part of this book discusses sequential utilization of wheat straw, material balance, and biorefinery approach. The approaches presented in this book will help readers/users from different areas like process engineering and biochemistry to plan integrated and inventive methods to trim down the expenditure of the industrial manufacture process to accomplish cost-effective feasible products in biorefinery.

Leseprobe

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Biorefinery Production Technologies for Chemicals and Energy

Edited by

Arindam Kuila and Mainak Mukhopadhyay

This edition first published 2020 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA and ScrivenerPublishing LLC, 100 Cummings Center, Suite 541J, Beverly, MA 01915, USA© 2020 Scrivener Publishing LLCFor more information about Scrivener publications please visit www.scrivenerpublishing.com.

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Library of Congress Cataloging-in-Publication Data

ISBN 978-1-119-59142-9

Cover image: Pixabay.ComCover design by Russell Richardson

Preface

Today, the world’s major economies are totally dependent on fossil fuels and other nonrenewable energy resources, and once substrate components are depleted, they will be gone forever. This has become an issue since, due to an ever-increasing world population, the use of technological devices in our everyday lives has been on the rise. In turn, the ever-increasing use of these devices has led to a rise in the use of fossil energy sources, resulting in a hike in global warming brought about by their consumption. Therefore, the world has been shifting toward sustainable development, including the generation of energy and industrially valuable chemicals from renewable substrates. Consequently, there is an eagerness to find alternative sources that are easily available and produce zero pollution. For example, in the search for possible fuel replacements, scientists hit upon the concept of producing fuel from lignocellulosic biomass, which is easily available in many forms, easily processed, cost-effective, and nonpolluting. However, whatever the source, biorefineries will play an important role in the integration of the conversion process with high-end equipment facilities for the generation of energy, fuel, and chemicals. With that in mind, this book was written as an invaluable resource for those interested in all aspects of biorefinery—from basic principles to end results.

The book is divided into four parts. The first part, “Basic Principles of Biorefinery,” covers the concept of biorefinery, its application in industrial bioprocessing, the utilization of biomass for biorefinery application, and its future prospects and economic performance. The second part, “Biorefinery for Production of Chemicals,” covers the production of bio-active compounds, gallic acid, C4, C5, and C6 compounds, etc., from a variety of substrates. The third part, “Biorefinery for Production of Alternative Fuel and Energy,” covers sustainable production of bioethanol, biodiesel, and biogas from different types of substrates. The last part of this book discusses sequential utilization of wheat straw, material balance, and biorefinery approach.

Dr. Mohd Asyraf Kassim (Universiti Sains Malaysia), Dr. Massimo Lucarini (CREA Research Centre for Food and Nutrition, Italy), Gunjan Mukherjee (Chandigarh University, India), Dr. Sachin A. Mandavgane (VNIT, Nagpur, India), and Dr. Ashok Pandey (Indian Institute of Toxicology Research, Lucknow, India) are just a few of the eminent scientists involved in the writing of this book. The book will be a useful resource for researchers and students in the areas of environmental biotechnology, bioprocess engineering, renewable energy, chemical engineering, etc.

Last but not least, we are grateful to the production team of Wiley-Scrivener Publishing for encouraging and extending their full cooperation and help for a timely completion of this book.

Dr. Arindam KuilaBanasthali Vidyapith (Deemed University), Rajasthan-304022, IndiaEmail id: [email protected]

Dr. Mainak MukhopadhyayJIS University, Kolkata-700109, IndiaEmail id: [email protected]

Part 1BIOREFINERY BASIC PRINCIPLES

1Principles of Sustainable Biorefinery

Samakshi Verma and Arindam Kuila*

Department of Bioscience and Biotechnology, Banasthali Vidyapith, Vidyapith, Rajasthan, India

Abstract

Sustainable biorefineries have a critical role to play in our common future. The need to provide more goods using renewable resources, combined with advances in science and technology, has provided a receptive environment for biorefinery systems development. Biorefinery offers the promise of using fewer non-renewable resources, reducing CO2 emissions, creating new employment, and spurring innovation using clean and efficient technologies. Lessons are being learned from the establishment of first-generation biofuels operations. The factors that are key to answering the question of biorefinery sustainability include: the type of feedstock, the conversion technologies and their respective conversion and energy efficiencies, the types of products (including co-products) that are manufactured, and what products are substituted by the bioproducts. The BIOPOL review of eight existing biorefineries indicates that new efficient biorefineries can revitalize existing industries and promote regional development, especially in the R&D area. Establishment can be facilitated if existing facilities are used, if there is at leastone product which is immediately marketable, and if supportive policies are in place. Economic, environmental, and social dimensions need to be evaluated in an integrated sustainability assessment. Sustainability principles, criteria, and indicators are emerging for bioenergy, biofuels, and bioproducts. Practical assessment methodologies, including data systems, are critical for both sustainable design and to assure consumers, investors, and governments that they are doing the “right thing” by purchasing a certain bioproducts. If designed using life cycle thinking, biorefineries can be profitable, socially responsible, and produce goods with less environmental impact than conventional products … and potentially even be restorative!

Keywords: Biorefineries, environmental impacts, sustainable development

1.1 Introduction

Sustainable development is a positive socio-economic modification which allows ongoing and upcoming generations to encounter their requirements. In order to do this, development has to assist the natural and social systems as it is based on them. All the three dimensions (economic, environmental, and social) of development are interconnected with each other and schematically, the place where they meet is known as sustainability (viable). Sustainability is not static; it is highly vigorous because it varies with geographical surroundings and develops over time [1].

Figure 1.1 Sustainable development.

Because of increased production and exploitation of fossil fuel energy and use of certain materials and chemicals, it causes huge environmental destruction which takes us to unavoidable termination that there should be the development of new production systems. These new systems of production should work on reducing pollutants or harmful materials and will produce safe and eco-friendly products within the green and sustainable supply chain. A renewable and constant supply having low carbon cost is required to do this process. Biomass is the only source of such renewable feedstock globally [2].

There are several factors that are responsible for determining environmental sustainability which are following: types of products that are manufactured, feedstock types; the technologies with their energy and conversion efficiencies; which type of product is exchanged by bioproducts; how emissions are dispensed to these products; and how these bioproducts are utilized and discarded with the end of life [1].

There is a need of developments in sustainable production for commercialization, co-products, and energy carriers that are being developed from biomass by using biorefinery. There is a rapid development of technology among these areas. It is understood that biomass has all the elements which are present in fossil resources, whereas in different integration due to which we are able to conclude that ongoing and upcoming technologies will head toward the future depending upon low carbon, renewable, and sustainable economies [2]. In our common upcoming time, there will be an important role to play by sustainable biorefinery. As there is no such development within the biorefinery products and technologies, so there will be immense possibilities for great significance. Superior knowledge about upcoming climatic modification footprints, sustainability affairs and inventive technologies will lead us to select more informed methods which will help in developing our renewable resources so that they can fulfill the requirements of society as well as nature on “spaceship Earth” [1].

Necessity to provide more goods and servicesby utilizing renewable sources in combination with advances in science and technology together have provided a providential environment for the development of biorefinery systems. A more bio-based economy has proposed the assurance to manufacture and preserve new employment, minimize CO2 emissions, exploit lesser non-renewable resources, and motivate novelty by utilizing sterilized and more productive technologies. Developed biorefinery should be capable of furnishing future products [1]. A brilliant estimation of such products under various technology frameworks is required within the next decades so that sustainable designs must be consciously formulated and evaluated. Sustainability is not just about renewability or about ecosystem or about GHG emissions because human health effects, economical, environmental, and social work are all need to be directed. If we move rapidly without even knowing the full outcome of any new development, then accidental effects can evolvedas the land utilization problem has been demonstrated. Eventually, public favor for developing biorefinery, i.e., acquiring bioproducts, biofuels and bioenergy will be vanished if there is any variability regarding their faithful subscription toward society and nature. It is mandatory to address the awaking concerns in an understanding manner [1].

1.2 Biorefinery

According to the NREL (National Renewable Energy Laboratory), a process that involves various equipments and biomass conversion methods in order to produce transportation biofuels, biomaterials, biochemicals, and power and heat is known as biorefinery [3].

Biorefineries are defined by International Energy Agency (IEA) Bioenergy Task 42 as the sustainable handling of biomass into a spectrum of marketable products and energy. It incorporates the process of sustainability, multiple products, and system integration. According to the literature, biorefineries are often classified by predominant conversion technology or feedstocks. If the number of platforms and/or products increases, then biorefinery complexity also increases [1].

An integrated biorefinery is planned in order to provide sustainable supply of biofuels and to produce fine and large amount of biochemicals (e.g., ether, glycerol, methanol, and syngas) with least waste generation. Depending upon the various conversion technologies utilized, i.e., biological conversion, chemical conversion, and thermo chemical conversion, biorefineries are further divided into three major categories [4].

All over the world biorefineries are appearing in a variety of many sizes, forms, or configurations. Their development rely on the present infrastructure, accessibility of biomass raw material, the requirement of given products, and to get knowledge about how some policies like public acceptance, scale-up facilities, and the level of expenditure in research can help in alteration toward a more productive and greener compound economy [1].

According to Wellisch et al. [1] choosing a feedstock will have some social, environmental, and cost implications. There are majorly three types of biomass feedstocks through which a biorefinery can be served and they are given below.

Primary biomass feedstocks: This type of feedstocks contains biomass which is immediately directly collected from water bodies, agricultural area, or forest [

1

].

Figure 1.2 General concept of biorefinery.

Secondary biomass feedstocks: These are basically process sediments, i.e., black liquor or saw mill remnants which are released by the forest products industry such as lignin is released from a lignocellulosic biorefinery or food processing wastes is released from agricultural food industry [

1

].

Tertiary biomass feedstocks: These are mostly post-consumer remnants or wastes, i.e., wastewater, waste greases, and municipal solid waste [

1

].

Biorefineries are established by the exploitation of secondary (vs. primary) feedstocks, modification of existing facilities (vs. green field construction); at least one product is manufactured with benevolent renewable energy approaches and an existing market. Product-driven biorefineries are generally more complex systems than first-generation biofuels biorefineries [3].

1.3 Conversion Technologies of Biorefineries

In each category, there are various types of conversion technologies which are given below in a tabular format, i.e., Table 1.1 [5]. Choosing a correct conversion technology is not worthless, and this selection of a conversion method is based upon various factors such as the process productivity, the attribute and accessibility of biomass feedstocks, environmental and economical needs, the types of necessary products, and several other facets associated with the complete biorefinery supply chain [4].

There are typically five stages of biorefinery supply chain which are the following [4].

Figure 1.3 Five stages of biorefinery supply chain.

Figure 1.4 Four types of conversion technology in each category of biorefinery.

Different stages of biorefinery supply chain are associated with each other throughout the complete process via some important factors such as handling, storage, and transport. Additionally, there are some major key issues regarding specific stages of biorefinery supply chain [6].

Achieving sustainability, selecting a crop, and enhancing plantation efficiency are some major issues related to feedstock producers. Majorly, there are issues associated with the scale of operation within the preprocessing that can be approached as an opportunity either for on-farm added values to biomass or for a new, isolated industry. Scaling up of biofuels technologies is a major issue in conversion of biomass. Affordability, availability, and ease of use of the biofuel/bioenergy products are some major issues among consumers [4].

As we know, biorefinery conversion technology metamorphoses available biomass feedstocks in many other forms into various energy products which comprises of power and heat; gaseous fuels, i.e., syngas and biogas; and liquid fuels, i.e., alcohols, bio-oil and biodiesel. Any capable biorefinery system will become complex due to this great heterogeneity of products, biomass feedstocks, and conversion technologies. Additionally, different anxiety and norms could be directed at various biorefinery supply chains, and the decision maker will always requires a substantially ideal design solution, that will ultimately increases the complexity in the design and in the evaluation tasks also [4]. There are basically four types of conversion technology in each category of biorefinery which are shown in Figure 1.4.

1.4 Some Outlooks Toward Biorefinery Technologies

According to Kamm and Kamm [7], in research and development, there are basically three biorefinery systems that are involved nowadays: i) Whole-crop biorefinery (WCB) utilizes feedstocks, i.e., maize or cereals; ii) Green biorefinery (GB) utilizes naturally wet biomass, i.e., immature cereal, clover, lucerne, or green grass; iii) Lignocellulose feedstock (LCF) biorefinery utilizes naturally dry feedstocks, i.e., wastes and cellulose-containing biomass.

Table 1.1 Conversion technology in each category of biorefinery.

Conversion category

Conversion technology

Type of resource

Examples of resources

Products

End use

Physical

Mechanical

Both liquid and

Oil seeds,

Biogas, By-products,

Electricity, Heat,

Briquetting of biomass

solid biomass

Agricultural, forestry

and Liquid fuels

and Transport

Torrefaction

residues, and other waste

(bioethanol and

fuel

Grinding

biomass materials

biodiesel)

Distillation

Liquid-liquid extraction

Absorption

Chemical

Hydrolysis

Both liquid and solid biomass

Oil or fat waste, Rape seeds, and Soybeans

Liquid fuels (biodiesel)

Electricity, Heat and Transport fuel

Solvent extraction

Polymerization

Supercritical conversion

Transesterification

Biological

Enzymatic hydrolysis

Basically solid biomass but in case of anaerobic

Wheat

Biogas, By-products, and Liquid fuels (bioethanol)

Electricity, Heat, and Transport fuel

Anaerobic

Colza,

Digestion

Maize, Manure, Miscanthus,

Growing of biomass

digestion, wet

Fermentation

biomass

Potatoes,

Sewage sludge, and Sugar

Thermal

Pyrolysis

Basically solid

Agricultural residues,

Heat, Product gas,

Electricity, Heat

Combustion

biomass

Chicken litter,

Pyrolysis oil,

and Transport

Gasification

Wood logs, chips, and

and By-products

fuel

Liquefaction

pellets

(product gas, char)

Source: - E4Tech.com, http://www.e-sources.com//biomass_converion.htm (accessed June 30, 2012).

Physical methods are used to separate the biomass containing precursors within the first step of process. After that, the by-products and the main products are exposed to chemical or microbiological methods. Now, the main and by-products are left over with follow-up products which can further be treated or move into a conventional refinery. Hence, biorefinery is of dual significance because it undergoes biological genesis of respective feedstocks, and on the other hand, there is an uplifting in the biological traits of selected treatment and processing methods [7].

1.5 Principles of Sustainable Biorefineries

According to the IEA Bioenergy Task 42, sustainable handling of biomass into a spectrum of valuable products and energy is known as biorefining [8]. Although a very small amount of general list of biorefineries have been distinctly identified till now and several other kinds of biorefineries are still in growing phase, and it is acknowledged that all types of biorefineries will be developed and handled in a sustainable manner according to the social, economic, and environmental (SEE) aspects. Taking this in consideration, a biorefinery system should follow the given basic sustainability principles.

According to the SCM (Supply Chain Management), principles 4–7 have been allotted to biorefinery systems by the IEA Bioenergy Task 42 [8].

These seven principles of sustainable biorefinery system are predominating instructions for the analysis and design of a biorefinery. There is a requirement of getting further knowledge if they are implemented to specific cases. For example, principle 2 can be explained as a necessity on life cycle GHG radiation depletion or no threat to air, soil, water, etc. Additionally, other principles could also be acquired for biorefineries as an essential accretion, i.e., the principles of sustainable development [10] and 12 other principles of green chemistry [11].

1.6 Advantages of Biorefineries

There was a saying that “if we have energy than we have everything” is not properly right. If we have energy, then other requirements of humans can be resolved by producing sustainable biomass feedstock. Biorefineries convey these demands as well as it also address the SEE requirements of our society. They will significantly provide employment and rural development, accompanied by reduced production costs with the development of emerging technologies and economies of scale with reasonably low carbon costs [2]. Biorefineries are strengthened by manufacturing co-products and energy carriers due to which this system becomes more economic. There is a variation in feedstocks that can be geographically based, manufacturing a diversity of valuable products which discovers this process as the substantial nominee in upcoming sustainable developments. Biorefineries remit matters of sustainability from all point—social, economic, and environmental. This technology is based upon the combination of the science, agro-engineering, marketing disciplines, and chemistry which demands a new prototype in sustainable development [2].

1.7 Classification of Biorefineries

Nowadays, classification of biorefineries is based upon the types of feedstocks utilized, technological (implementation) status, or major type of conversion technology applied. According to the literature, there is a variety of terms explaining biorefineries—see Figure 1.5.

There is a more relevant classification of biorefinery system given by the IEA Bioenergy Task 42. This classification depends upon the simplified description of full supply chains from biomass to end product. Approximately, biorefineries can be categorized in major two types:

Energy-driven Biorefinery: Production of biofuels or energy is the main target. The characteristic biorefinery enumerate value to co-products.

Product-driven Biorefinery: In general, production of chemicals, feed, food, or materials is the main target of biorefinery method. Secondary energy carriers, i.e., heat or power, are produced by the side products both utilized for dispersing in market as well as in-house advantages.

IEA Bioenergy Task 42 has further divided the various biorefineries. This type of recommended classification depends upon the latest ruling operator in biorefinery development, i.e., effective and well-organized manufacturing of transportation biofuels, so that the sharing of biofuels can be extended in the transportation area. In order to identify, classify, and describe the various biorefineries, this classification approach involves four major following features:

Figure 1.5 Varieties of biorefineries.

There are four principal conversion technologies, i.e., biochemical (e.g., enzymatic conversion and fermentation), chemical (e.g., acid hydrolysis, esterification, and synthesis), mechanical processes (e.g., size reduction, pressing, and fractionation), and thermo-chemical (e.g., pryolysis and gasification).

Products (e.g., chemicals, feed, food, and materials) and energy (e.g., bioethanol, biodiesel, and synthetic biofuels) are two main biorefinery product groups.

Biomass residues from agriculture, forestry, industry, and trade (e.g., bark, straw, used cooking oils, waste streams from biomass processing, and wood chips from forest residues) and energy crops from agriculture (e.g., short rotation forestry and starch crops) are two major feedstock groups within this type of classification.

Several biorefineries and their processes are linked with each other through an intermediates called as platforms (e.g., biogas, C5/C6 sugars, and syngas). Biorefinery systems complexity will increases with the increase in number of platforms.

Classification of biorefineries is done by stating the involved feedstocks, platforms, products, and, if mandatory, the processes. Some examples of classifications are follows.

Animal feed and bioethanol is produced from starch crops by utilizing C6 sugar platform biorefinery.

Phenols and FT-diesel are produced from straw with the help of syngas platform biorefinery.

Bioethanol, FT-diesel, and furfural are produced from saw mill residues via C6 and C5 sugar and syngas platform biorefinery.

1.8 Conclusion

Conclusively by adding value to the renewable utilization of biomass, biorefineries can play an advantageous role toward sustainable development. Biorefineries can feed the full bio-based products by producing a spectrum of bioenergy (i.e., fuels, heat, and power) and bio-based products (i.e., chemicals, feed, food, and materials). It should be noticed that the economic situation of market areas, i.e., agriculture, chemical, energy, and forestry is strengthened by reducing feedstocks demands and exploiting biomass conversion effectiveness. According to the international consent availability of biomass is insubstantial that means biomass feedstocks should be utilized as efficiently as possible resulting in development of multi-purpose biorefineries in an organization of deficient feedstocks and energy.

One of the remarkable success factors for biorefineries is bringing together key stake-holders normally operating in different market sectors (e.g., agriculture and forestry, transportation fuels, chemicals, energy, etc.) into multi-disciplinary partnerships to discuss common biorefinery-related topics, to foster necessary R&D direction, and to accelerate the deployment of developed technologies (platform function).

Task 42 can contribute to the growth of biorefineries by identifying the most promising bio-based products, i.e., food, feed, added-value materials, and chemicals (functionalized chemicals and platform chemicals or building blocks) to be co-produced with bioenergy, to optimize overall process economics, and minimize the overall environmental impact. Major initiatives in the immediate future include the preparation of a review and guidance document on approaches for sustainability assessment of biorefineries, and a strategic position paper “Biorefineries: Adding Value to the Sustainable Utilization of Biomass on a Global Scale”.

References

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Biofuel. Bioprod. Bior. Innov. Sustain. Econ.

, 4, 3, 275–286, 2010.

2. de Jong, E., van Ree, R., Kwant, I.K., Biorefineries: Adding value to the sustainable utilisation of biomass.

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, 1, 1–16, 2009.

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Energ. Fuel.

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4. Liu, Z. and Eden, M.R., 22 Biorefinery Principles.

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, 447–474, 2014.

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http://www.e-sources.com//biomass_converion.htm

(accessed June 30, 2012).

6. Wisconsin Grasslands Bioenergy Network.

http://www.wgbn.wisc.edu//biomass-supply-chain

(accessed June 30, 2012).

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Appl. Microbiol. Biotechnol.

, 64, 2, 137–145, 2004.

8. Cherubini, F., Jungmeier, G., Wellisch, M., Willke, T., Skiadas, I., Van Ree, R., de Jong, E., Toward a common classification approach for biorefinery systems.

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, 3, 5, 534–546, 2009.

9. Batsy, D.R., Solvason, C.C., Sammons, N.E., Chambost, V., Bilhartz, D.L., Eden, M.R., Stuart, P.R., Product portfolio selection and process design for the forest biorefinery, in:

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Design, analysis, and optimization

, P.R. Stuart and M.M. El-Halwagi (Eds.), pp. 837–845, CRC press, Boca Raton, Florida, 2013.

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Education for sustainable development toolkit

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, 29–56, 1998.

Note

*

Corresponding author

:

[email protected]

2Sustainable Biorefinery Concept for Industrial Bioprocessing

Mohd Asyraf Kassim*, Tan Kean Meng, Noor Aziah Serri, Siti Baidurah Yusoff, Nur Artikah Muhammad Shahrin, Khok Yong Seng, Mohamad Hafizi Abu Bakar and Lee Chee Keong

Bioprocess Technology Division, School of Industrial Technology, University Sains Malaysia, Penang, Malaysia

Abstract

In this chapter, the production of various value-added products including biofuels and fine chemicals from renewable resources are reviewed. Initially, the biorefinery concept and its development of different renewable resources are discussed. Then, different processes such as thermochemical, biochemical, and chemical conversion technologies involved in producing various products are reviewed. The processes and steps involved in each conversion approach for wide range chemical production are also discussed. This chapter also reviews the types of biofuels and fine chemicals that can be produced from various renewable resources through biorefinery concept for sustainable industrial processes.

Keywords: Bioethanol, microalgal, lignocellulosic material, renewable, biomass

2.1 Sustainable Industrial Bioprocess

Sustainable development has sparked great interest as an approach to overcome global issues. Nowadays, many countries have put sustainability as a main priority for their policy makers. Sustainable development is a complex approach with the aim to manage natural resources, generate, and improve welfare for future generations. The processes used to achieve sustainability must be reliable where several strategies have been introduced to ensure the success of this approach including waste reduction, pollution reduction, material reuse, and value creation.

Among the technologies that play important role for sustainable development plans, bioprocess technology is identified to contribute especially in the fields of food production, chemical, bioenergy, pollution control, and bioremediation. Modern industrial bioprocess technology is an extension of conventional technique which is important to be transferred to applications in the industry. The industrial bioprocess uses complete living cells or their components including enzymes and metabolites to obtain desired products.

Figure 2.1 Three spheres of sustainable bioprocess.

Sustainable bioprocess has to be developed with the aim to improve social, environment, and socio-economic in the society (Figure 2.1) [1]. These three components are important and not independent of each other [2]. Sustainable bioprocess has more multi-variable situations involving many groups with the aim to minimize environmental impacts and be more economically viable and socially responsible [3]. It has to develop new products and explore new applications of agro-wastes generated from industries. Providing new technologies and industries will create job opportunities and grow special skills for human capital development. Apart from that, this system will diversify economic growth especially in rural areas. Implementation of sustainable bioprocess could also provide carbon neutral technology to assist in reducing global warming. Development of new approach and technology could reduce waste production and pollution especially in foods, chemicals, and agricultural industries. According to Henderson et al. [4] in their study in the comparison of 7-ACA’s production, they concluded that production using biocatalytic reaction exhibited “greener” technology compared to chemical reaction as this process is safe and less hazardous due to low usage of chemicals.

2.2 Biorefinery

At present, chemicals and energy are among the most important commodities that play important role in daily life. Both are produced globally every year through refining, totally dependent on petroleum-based feedstocks for their production. Overdependence on these has slowly reduced petroleum reserves. It is evident that these activities have led to uncontrolled emission of greenhouse gases (GHG), including carbon dioxide (CO2), methane, and nitrous oxide (N2O).

This current scenario has pushed scientific community to explore replacements of renewable carbon sources and development of biorefinery system to produce wide spectrum of products including biofuel, energy, and high-value chemicals from biological-based feedstocks through a combination of different biomass transformation technologies [5, 6]. A biorefinery is a facility that integrates biomass conversion processes together with the equipment to manufacture products, similar to today’s petroleum-based refinery in which chemicals, chemical products, and fuels are produced from crude oil. The products manufactured from the biorefinery process must be able to partially replace chemicals and fuels generated from the oil refinery.

Table 2.1 Differences between oil refinery and biorefinery.

Oil refinery

Biorefinery

Feedstock

Petroleum-based Relatively homogeneous

Biological-based Heterogeneous (Cellulose, hemicellulose, lignin, protein, carbohydrate)

Building block/intermediate

Ethylene, propylene, toluene, xylene

Sugar (Glucose, xylose, fructose), fatty acid

Reaction

Chemical process: steam cracking, catalyst reforming

Combination chemical-biotechnology, Involve series of biochemical reaction to obtain building block, Fermentation

Chemical intermediate

Many

Ethanol, methane, furfural, hydroxymethyl, lactic acid, succinic acid, acetic acid, glycerol

Table 2.1 shows the comparisons between biorefinery and oil refinery processes in chemicals and biofuels production [7]. The major difference between these two refinery concepts is the nature of feedstock or raw materials. Crude oil rich with hydrocarbon and mixture of sulfur with low oxygen contents are typically used as feedstock for oil refinery. While biomass or agro-waste that consists of carbohydrate, protein, cellulose, hemicellulose, and lignin are the common chemical compounds in the biorefinery feedstock. The second aspect that can be observed from these two refinery concepts is the building blocks generated from the reaction of the feedstocks. Building blocks produced are vital as a precursor to the targeted final product formation. In oil refinery process, the main building blocks generated from chemical reaction of petroleum are ethylene, propylene, xylene, toluene, and other isomers. In contrast, organic carbon such as glucose, xylose, and other fatty acids are the main building blocks produced from biochemical reaction of biomass.

Biorefineries can be classified according to the basis of their key characteristics. There are several types of biorefineries such as whole crop biorefinery, lignocellulosic biorefinery, green biorefinery, two-platform biorefinery, and microalgal biorefinery [7, 8]. Most of the biorefinery classifications are based on the generalization on the types of feedstock this concept must fit, even though the system is introduced to achieve similar aim. It is expected that the classification of biorefinery to be more flexible as this concept will deal with various approaches in the biorefinery system [9]. For this chapter, three different biorefineries that support sustainable bioprocess system will be described: starch biorefinery, lignocellulosic biorefinery, and microalgal biorefinery.

2.2.1 Starch Biorefinery

Starch is one of the most abundant storage carbohydrates that can be extracted from wide ranges of agricultural raw materials including seeds, tubers, roots, and fruits. This storage carbohydrate polymer consists of glucose molecules that are linked together by glycosidic bond (alpha 1,4 and alpha 1,6). Most of the starch contain predominantly up to 20%–30% of amylose followed by amylopectin (Figure 2.2). Amylose is a water soluble polysaccharide that forms glucose subunit. While amylopectin is a highly branched polysaccharide consisting of alpha glucose units. This polymer is insoluble in water and it contributes approximately 70% of the starch.

Table 2.2 shows the proximate chemical compound distribution in the various types of starch crops. Genrally, starch-producing crops are a group of plants that carry out photosynthesis and accumulate starch as energy reserves. Examples of starch-producing crops are barley, wheat, potato, bean, and banana.

Starch biorefinery is considered as first generation biorefinery that is based on utilization of agricultural biomass and forestry products. The most common substrates used for the starch biorefinery are cassava and corn. Figure 2.3 shows the common schematic flow process of starch biorefinery. The first step is mechanical separation. At this initial stage, straw is separated from seed. The straw that consists of cellulose, hemicellulose, and lignin can be further processed for production of other valued-added products. While the seed fractions produced at the initial stage may be converted into starch or ground for meal or animal feed. The starch can be processed into other desired products such as sweetener, acid, alcohol, or biofuel via fermentation of other chemical reactions including plasticization, polymerization, and chemical modification.

Figure 2.2 Amylose and amylopectin structure in starch materials.

Table 2.2 Chemical composition of starch-producing crops according to percent dry weight.

Cereal

Crude protein

Crude fat

Crude fibre

Carbohydrate

Ash

Sorghum

8.3

3.9

4.1

62.9

2.6

Oats

9.3

5.9

2.3

62.9

2.3

Barley

11.0

3.4

3.7

55.8

1.9

Wheat

10.6

1.9

1.0

69.7

1.4

Potato

2.19

0.25

0.3

24.29

1.2

Cassava

7.81

0.3

2.15

38

0.85

Figure 2.3 General schematic diagram for a starch biorefiney.

There are several limitations and issues that have been address associated with the production of biofuel and chemicals in starch biorefinery. Among the most well-known issue is risk of an over consumption of food crops and utilization of land for starch crop production. The limitation of arable land for food crops production has become competative, which also lead to the deteriation of organic quality of the mineral content in soil making fist generation biorefinery not feasible. On the other hand, exhausive utilization of chemical fertilizer for food crop production has significant impact on the environmental sustainability. Hence, exploring new feedstock for biorefinery is crutial to improve the sustainable production of chemicals and fuel from renewable resource is feasible.

2.2.2 Lignocellulosic Biorefinery

Biomass is one of the most important renewable resources on earth. Biomass refers to any organic matters which are renewable or available on recurring basis. It can be food, wood, and crops or waste from plant materials and animals (Table 2.3). Besides, another type of biomass which is always neglected or forgotten is biomass from microorganisms such as bacteria, yeast, and fungi. Lignocellulosic biomass is predominantly derived from cell walls of plants in which cellulose, hemicellulose, and lignin are the three major chemical compositions with minor amount of protein, pectin, and minerals. The quantity of each chemical composition varies depending on the types of plant such as crops, grass, and wood (hardwood, softwood) and the age of the plant tissue [10, 11]. They are cross-linked and bound together via different types of bonding to form a very strong and complex structure. A multi-enzyme complex of cellulase, hemicellulase, and ligninolytic is required to act cooperatively and sometimes synergistically to complete the degradation of lignocellulosic biomass [12–14].

Table 2.3 Different types of common lignocellulosic biomass.

No

Type of lignocellulosic biomass

Example

1

Woody

Saw dust, forest residues

2

Non-woody

Paddy straw, wheat straw, sugarcane bagasse, palm kernel cake, rice husk Corn stover, wheat bran

3

Microorganisms

Fungi Bacteria Yeast

4

Organic waste

Human sewage sludge Livestock wastes

Lignocellulosic biomass has been determined as the most crucial source for the production of wide variety of polymeric materials [11]. This is due to cellulose being one of the most examined biopolymer and has been studied for a long time [15, 16]. It is a major constituent of plant cell wall and is also found in microorganisms (fungi, bacteria, algae) [17]. It is an essential feedstock for many industries such as biofuels production, pulp and paper, wood products, etc. [15, 16]. Biomass conversion process to produce valuable products is designated as the biorefinery process.

Van Dyne et al. [18], Kamm and Kamm [19], and Fernando et al. [20] have described three types of biorefinery processes known as Phase I, II, and III biorefineries. These three phases are different in terms of number of feedstocks used to produce different number of products via different number of processes (Table 2.4) with Phase III being the most advanced/ developed type of process. On top of that, lignocellulosic feedstock (LCF) biorefinery is one of the Phase III biorefinery systems actively being conducted in research and development [21].

Lignocellulosic feedstock biorefinery (LFB) system commonly uses “nature-dry” lignocellulosic biomass as feedstock. The feedstock can be bagasse, wood, stover straws, oil palm biomass, etc., which are mainly comprised of six carbon glucose polymers, hemicellulose (five carbon sugar polymers), and lignin (phenol polymer) [20, 21]. These three major chemical constitutes will be fractionated before converted into a variety of products (fuels, chemical products, adhesives, xylites, etc.) [19]. In general, the cleaned feedstock (biomass) will be fractionated into three major fractions via chemical (digestion) or biological (enzymatic hydrolysis) process in which they serve as precursors to many other products (Figure 2.4) [19].

Different lignocellulosic biomass requires different process conditions during production and they also need to be optimized for every single feedstock use. Cellulose and hemicellulose can be obtained via enzymatic hydrolysis of lignocellulosic biomass using cellulase and hemicellulolytic enzymes complex. These hydrolysis processes will convert cellulose and hemicellulose into their respective sugars and byproducts such as glucose, galactose, mannose and xylose, arabinose, furfural, etc. However, they can also be produced using chemical or heat treatment processes such as autohydrolysis (autoclaving), alkaline (caustic soda), and sulfite (acidic, bisulfite, etc.) [20]. On the other hand, lignin component in lignocellulosic biomass can be broken down using lignin-modifying enzymes which mainly consist of lignin peroxidase, manganese peroxidase, and laccase.

Table 2.4 A general overview of three types of biorefinery processes.

Phase

Feedstock

Process

Major product

I

Single

Single

Single

Rape seed

Transesterification

Biodiesel

II

Single

Multiple

Multiple

Cereal grains

Pre-treatment

Polymers

Enzymatic

Vitamins

Fermentation

Amino acids

Chemical and/or biochemical catalysis

Polyols

Biofuels

Hydrocolloids

III

Multiple

Multiple

Multiple

Cereals (straw)

Pre-treatment

Sugars (xylose, glucose)

Paper and cellulosic municipal solid waste

Enzymatic

Fuels (ethanol)

Fermentation

Organic acids (lactic acid)

Lignocellulosic biomass (reed, reed grass

Grinding

Chemical processes

Solvents (acetone, butanol)

Biological processes

Forest biomass (wood)

Emulsifiers

Stabilizers

Furfural (furan resins)

Nylon

Natural binder

Figure 2.4 A general overview of the conversions that takes place in a LCF biorefinery.

Glucose which is the precursor to a variety of useful products such as ethanol, hydroxymethylfurfural, acetic acid, acetone, and other fermentation products is fractionated from cellulose hydrolysis. On the other hand, xylose which is one of the breakdown products of hemicellulose can be used to produce xylite and furfural (the building blocks for many useful products such as levulinic acid, lubricants, Nylon 6, fuel derivatives, cleaning agents, etc.) [19, 20]. However, lignin has lesser use when compared to cellulose and hemicellulose. So far, it is applied as fuel or binder. Many active researches have been conducted on the use of lignin for formation of more valuable products. Lignin can be pelletized by mixing with biomass to be used as solid fuel for easier transportation [21]. With the increase in lignin application, the overall LCF biorefinery process will be more competitive and value-added in producing useful industrial products such as cellulosic ethanol.

In conclusion, LCF biorefinery process has been successfully demonstrated to produce wide variety of useful industrial products such as biomaterials, chemicals, and energies/ fuels. Nevertheless, it has to compete with existing petroleum refinery process which contributes more than 90% of industrial economies [22]. In order to maintain the competitiveness of LCF biorefinery, besides ensuring optimum yield of primary products, establishing value-adds to the byproducts generated are essential to lower the cost of overall process.

2.3 Microalgal Biorefinery

Microalga is a photosynthetic microorganism that is able to undergo photosynthesis by mitigating carbon dioxide (CO2) from the atmosphere. The biomass produced from photosynthesis is also able to convert to various valuable products such as biofuel, bioethanol, and other wide range of chemicals. Microalga exhibits several interesting properties as a renewable material such as [23]:

Easy to grow

Short maturation time

Higher growth rate

No need special attention or culture condition

Contains different biochemical components such as carbohydrate, protein, and lipid in biomass

Microalgal biorefinery can be defined as an approach to obtain full valorization of each raw component in the microalgae ranging from species selection, cultivation, harvesting, and lipid extraction [24]. Microalgal biorefinery was initially introduced by Khan, Ahmad [25] in which it was applied in biogas and biofuel industries. This concept has been widespread in various industrial sectors such as food, pharmaceutical, energy, chemical, and feed industries.

Nowadays, microalgal biorefinery has been explored for the synthesis of bio-based products [26]. In order to enhance the efficiency of by-products conversion, this concept has been identified as the most promising way to create biomass-based industry due to its potential in forming multiple products. The design of microalgal biorefineries should maximize outputs and profit from single algae biomass as a raw material source [27]. For example, Burton, Lyons [26] reported that glycerine is the potential co-product of biodiesel production through biorefinery process specifically transesterification of microalgae. The conversion of co-product with higher economic value is a value-add to the microalgal biofuel production. Typically, microalgal biorefinery technology has presented bottlenecks that are mainly associated with upstream processing (USP) and downstream processing (DSP).

Figure 2.5 The upstream process involved in microalgae cultivation.

2.3.1 Upstream Processing

The efficiencies of the USP are highly dependent on the microalgae strain, illumination, and carbon dioxide (CO2) supplied and nutrient sources’ availability such as nitrogen and phosphorus (Figure 2.5). All these variables were proven by previous studies to be significant to the microalgal growth and biomass production [27]. It was reported by previous studies that different microalgae strains possess different percentage of biochemical components and the data are summarized in Table 2.5.

All of these chemicals are important to ensure the feasibility of DSP. The potential of high value-added chemicals from the microalgal biomass is totally dependent on the chemical components present in it. For example, the microalgal lipid can be converted into biodiesel, while microalgal carbohydrate can be converted into bioethanol or other chemicals via fermentation process. Whereas protein is important in food industry [26].

The formation of biochemical compounds in the microalgal biomass could be affected by several factors including mode of cultivation condition and parameters. It was reported that a higher growth rate was observed in Chlorella sp. microalgae when illuminated under artificial light condition [31]. This was due to the light source that stimulated photosynthesis system in microalgae cell and subsequently enhanced its growth rate. Besides that, CO2 was reported by the previous study to be attributed to microalgae growth rate by directly affecting the environment’s pH condition for several species such as Chlorella sp., Zygnema sp., Scenedesmus sp., Hizikia fusiforme, Chaetoceros spp., Microcystis aeruginosa, Botryococcus braunii, Nannochloropsis sp., Ulva rigida, Chlorococcum sp., Spirulina sp., Prorocentrum minimum, and Mytilus edulis [32]. Lastly, nutrient sources are vital for microalgae growth production in which they can activate certain genes to enhance microalgae growth and biomass production [33].

Table 2.5 Differences in biochemical compositions exhibited in different microalgae strain.

Microalgae strain

Biochemical compositions

References

Carbohydrate

Protein

Lipid

Amphiprora

sp.

6.2

10

12

[

28

]

Chlorella

25.2

53.3

15.7

[

29

]

Neochloris oleoabundans

37.8

30.1

15.4

[

29

]

Phaeodactylum tricornutum

46.78

36.67

1.07

[

30

]

2.3.2 Downstream Processing