Circular Bioeconomy Perspectives in Sustainable Bioenergy Production

Energy security and climate change risk are the two daunting issues faced by developing economies across the globe. The industrial, agriculture and transport sectors in developing nations follow a linear model of economy based on a “take-make-dispose” pattern. The circular economy model that follows the pattern of “reduce-repair-recycle-reuse” offers a potential solution. This book has dealt with the application of circular economy principles to the energy sector. Basically, this book has covered diverse aspects and issues related to the generation of energy from waste and sustainable resources. The topics covered by the book chapters include energy generation (in the form of liquid and gaseous fuels) from agro- and forest residues, municipal solid wastes, industrial organic wastes and food wastes. Technical and economic viabilities of the thermochemical and biochemical technologies for sustainable energy generation as well as issues related to supply chain management of waste resources have been assessed. On a whole, this book has attempted to identify both opportunities and challenges for application of circular bioeconomy models for bioenergy generation, which could be useful for various stakeholders from academia and industry.

Bioenergy is a renewable energy that can be obtained, from biological resources in abundance. The resources include microorganisms, plants, animals and recently, biomass. The applications of bioenergy are wide. It can be used for cooking purpose, power generation, etc. It can also be used as a substitute for petroleum products in both liquid and gaseous forms. Bioenergy is been considered as Nextgen fuel, replacing the other fossil fuels, either partially or completely. Bioeconomy refers to a prudential usage of bioenergy obtained from biological resources. It also deals with conservation of bioenergy, thereby, aiming at sustainable economy for the human welfare. The precise meaning of biological resources not only includes plants, animals, microorganisms or biomass but also the relatable scientific and technological knowledge and innovative ideas based on the same. In the early twenty-first century, the European Union (EU) and Organization of Economic Cooperation and Development (OECD) provided a spotlight on bioeconomy concept. The strategies of bioeconomy, in a holistic approach, aim at sustainable development with circular economy. Sustainable bioeconomy strongly focuses in mitigating global challenges like depletion of fossil fuels, endangered biodiversity, unpredictable inconsistent climatic changes, environmental pollution, etc. It paves a new approach by promoting green-based employment. Thereby, our country’s economic status will escalate. Its paramount focus is on the manufacture and consumption of world’s finite resources the bioenergy, in an equitable proportion with circularity. This chapter deals with the bioenergy, bioeconomy, circular economy, perspectives, and challenges of the same.

The green lignocellulosic biomass industry is now gaining recognition as an appealing substitute for fossil resources, seeking to balance the world’s escalating dependency on petroleum while being economical. The resurgence of the most abundant lignocellulosic resources into effective goods is an intriguing option for diminishing greenhouse gas emissions. Aromatic lignocellulose is a complex carbohydrate polymer composed of polysaccharides derived from xylose, glucose, and lignin. The interior framework of lignocellulosic matter is responsible for plant cell walls’ hydrolytic resilience and rigidity, rendering them immune to microbial destruction. Recycling of residues leads to less dumping of waste. The chapter mainly concentrates on commercializing lignocellulosic waste biomass in the contemporary period to develop alternative biofuels, which encompasses diverse processes such as prior treatment, saccharification, and oleaginous microbe-mediated fermentation. Different means of prior treatment are implemented to conquer the inflexibility of LCB and advance its breakdown into hemicellulose, lignin, and cellulose. Components such as bioethanol, biodiesel, and biobutanol from the lignocellulosic feedstock act as inhibitors of detoxification and play major roles in strain enhancement, process integration, and optimization, which are the main fundamentals for boosting biofuel synthesis. The re-engineering of lignocellulosic material to extract fuel alternatives has tremendous potential because of its enticing features, comprising low density, affordability, green credentials, and biodegradability.

Bioenergy production has developed as a sustainable solution to address the increasing energy demand while decreasing environmental pollution. The industrial sectors are increasing along with the fast population growth and urban developments. Due to various activities, a significant amount of organic waste and byproducts are generated in the industrial sectors. If improperly processed, this organic waste with high nutritional content might cause environmental contamination and speed up climate change. However, with suitable technologies and procedures, waste materials could be used to produce valuable bioenergy sources. Converting industrial organic waste and byproducts into bioenergy is a sustainable and environmentally friendly approach. Besides, it offers several eco-economic benefits, such as reducing reliance on fossil fuels, mitigating environmental pollution and reducing landfilling. This chapter explores the potential of industrial organic waste and byproducts as feedstock for bioenergy generation and its implications for sustainable energy production.

Undeniably higher feedstock costs are hindering the commercialization of biodiesel production. Amidst the mentioned problem, there is a current exploration of alternatives like waste cooking oil (WCO). WCO holds the promise of substantially reducing production costs by 60–90%, attributed to its cost-effectiveness compared to vegetable cooking oils and energy crops. Microwave-assisted transesterification of WCO is a time-efficient process that yields high quality and quantity of fatty acid methyl esters (FAMEs) with a lower molar ratio of methanol to oil. Besides the growing interest in using microwaves for WCO transesterification, a comprehensive review of the technology for analysing factors affecting biodiesel production, and the challenges and limitations for process scale-up and commercialization is essential which is currently limited. The chapter illustrates the significance of microwave heating of WCO for biodiesel production. Further, the influence of parameters on the quality and quantity of biodiesel has also been discussed. The process energy requirement in comparison with the conventional method has been analysed. Challenges and limitations associated with technology commercialization have been annotated. Overall, this chapter enables the researchers to understand the technology-driven biodiesel production through microwave irradiation of WCO and identify the potential loopholes to make the process sustainable.

The impact of any processing technology on sustainable development requires a zero-waste approach of reusing, recycling, and recovering. Biodiesel serves as an alternative source of renewable energy to fossil fuels, and it can be produced by transesterification of feedstock with alcohol in the presence of a catalyst. Nanocatalysts are preferred in the transesterification reaction when compared to acid, base, and enzymatic catalysts due to their high surface-to-volume ratio, high catalytic activity, easy recoverability, simple synthesis procedure, and low toxicity. Calcium and carbon-based green catalysts that offer a large surface area, improved porosity, stability, and inertness can be derived from plant, agricultural, and animal wastes. This chapter discusses the role of various green catalysts that are derived from biomass, along with their merits and demerits for large-scale production of biodiesel, and the possible ways of improving the yield to make biodiesel viable for commercial applications.

The use of plastics and the growth of modern plastic industries began in the early twentieth century, thus providing the human populace with a very useful tool that found widespread applications in various sectors. Mostly synthesized from petrochemicals, plastic’s high durability makes it one of the most widely used synthetic materials. Its characteristic properties like lightweight, ability to be molded, insulating ability, and resistance against degradation have made it an ideal choice for being used to manufacture different consumer goods, medical equipment, and safety gears. The hospital sector is one of the largest users of plastic products owing to their non-reactive and durable nature simultaneously producing a proportionate amount of disposable plastic waste. The COVID pandemic saw a huge rise in the use of plastic-based materials in the healthcare sector, thus increasing the waste load in the environment. The long-term environmental persistence of plastics due to their non-biodegradable nature coupled with improper disposal and conventional waste management systems have led to the accumulation of these synthetic polymers in different environmental matrices, thereby causing pollution. It is essential to devise sustainable solutions to reduce the load of plastic waste in the environment, thereby nullifying its toxicity. In this context, the conversion of plastic waste into suitable energy forms is suggested as a means to sustainably reduce the plastic contaminants in the environment and parallelly supply energy alternatives to the dwindling conventional energy resources.

Biomass is a renewable energy source generated from agricultural waste, solid waste, etc. In addition to being utilized extensively for storing energy and gas, biomass is a major source of catalysts for biodiesel production. Biochar is a by-product of thermochemically degrading biomass through processes like pyrolysis, hydrothermal conversion, carbonization, etc., which has great potential as an energy storage material, a precursor to nanotubes and graphene, and as a catalyst for various chemical reactions. The high porosity, large surface area, low cost, and ease of generation make biochar a great contender for a catalyst. The post modification includes the physical or chemical activation which makes the surface area larger by increasing the pores. It also includes functionalization by adding a specific functional group for a particular chemical reaction. Acid-functionalized and base-functionalized biochar can be used for the transesterification of triglycerides and the esterification of free fatty acids. This production of biodiesel using functionalized biochar as a catalyst can be enhanced by optimizing different reaction parameters like time, temperature, etc. Overall, functionalized biochar is a strong candidate as a catalyst for the production of biodiesel.

The result in climate change, fossil resource depletion, and transportation alternatives to petroleum are in great demand. The structural components belonging to lignocellulosic biomass like lignin, cellulose, hemicellulose and as well as technological unit phases like pretreatment and as well as hydrolysis of enzymes are discussed. The sole purpose of pretreatment stage is to increase the surface area of carbohydrate that is available for the enzymatic saccharification and also lower the inhibitor concentrations. The review focuses on bioethanol production from lignocellulosic biomass derived from plants. For synthesizing effective bioethanol, diverse lignocellulosic biomass like feedstocks of wood, agricultural wastes, and marine algae are used as substrates, and different enzyme techniques are used in hydrolysis protocols. This paper provides a detailed review in the synthesizing of lignocellulosic bioethanol via biochemical pathway while focusing on the widely used pretreatment technologies as well as important enzymatic hydrolysis and fermentation operational parameters in accordance to the yield of sugar and ethanol. Also, the importance of immobilization is discussed in this study as well as numerous detoxification processes for eliminating hazardous substances. According to this review, modified microbes could potentially be employed to boost fermentation of glucose and xylose, cellulolytic enzyme synthesis and also stress response.

Global urbanization against rural settlements has been on a steady rise over the past 6 decades. Nearly one-third of the entire population of India residing in urban locations (roughly 5.5% of available residential land) has placed an unprecedented burden on the municipal economy, energy utilization, and waste management systems. Sustainability as regards resources and municipal solid waste (MSW) management remains a challenge. The focus of this chapter concerns these challenges, the various avenues for processing MSW, biorefinery approaches for de-novo generation of commercial products, energy, etc. Additionally, the sustainability of these approaches, cost to the taxpayer, and the conversion of MSW to value-added resources or energy are also discussed. Harnessing bioenergy from MSW biomass may be an attractive route for addressing the ongoing global energy crisis. Carbon dioxide can be trapped via reactive amines to reduce emissions and generate value-added compounds such as urea. Certain wastes within MSW can be processed to obtain glycerol-based compounds which have wide applications in industry. Segregated waste management strategies will help in selectively processing organic wastes using the biorefinery route, which entails broad-spectrum cellular/enzymatic tools to break down the organic material. Systematic management of MSW can be expected to be a major resource salvage route. Harvesting MSW is thus proposed here to be a vital mechanism to generate a circular bioeconomy aimed at sustainability and economic viability.

The challenge of waste disposal and management has become more prominent with increasing awareness. In rural areas, natural waste management is carried out within available space constraints. The conventional methods used for solid waste disposal include burning, landfilling, and composting, often regarded as the most effective and widely used practices. There is a significant concern over the adverse environmental consequences of implementing non-sustainable practices in solid waste management. This chapter aims to comprehensively analyse the many sources of solid waste, focusing on lignocellulosic biomasses originating from rural areas, mainly within the Indian sub-continent. Pyrolytic conversion is a thermal process that transforms waste materials into three distinct forms: solid residue known as char, liquid fuel, and gaseous emissions. Recent research has concentrated on using food waste as an energy source (e.g. for the manufacture of bioethanol and biodiesel) rather than disposing of and decomposing it. Utilizing a biorefinery or biotechnology, organic waste can also be used to produce valuable organic chemicals, such as succinic acid and/or bioplastics. The chapter further provides a detailed explanation of mapping secondary data from different departments and contrasts it with previously conducted research studies. This chapter is intended to summarise the facts on the efficient use of biochar for pollution control and environmental management.

At Biogasbolaget AB in Karlskoga in south-central Sweden, organic wastes like food waste, manure, and silage are digested anaerobically to yield biogas, which subsequently can be upgraded to biomethane, and used as a replacement for fossil-diesel in public transport. The digesters at the firm are currently operating below their maximum capacity. This chapter deals with the evaluation of the potential of hydrochar to augment biogas production in a batch process. Hydrochar produced from two sources—forestry sector and municipal organic wastes—were compared, and using the Automatic Methane Potential Testing System (AMPTS II) in the lab at Karlstad University, the optimal dosage was determined. Experiments were also conducted with hydrochar alone, to verify if the hydrochar was being anaerobically digested to yield biogas. The hydrochar sourced from municipal waste, when dosed at 8 g/l, produced 841 Nml of biogas/gram of VS (volatile solids) in the substrate, 93% greater than the reference case of no addition of hydrochar. The forestry-sector-sourced hydrochar on the other hand, at the same dosage, registered an increase of just 16.6%. A streamlined environmental life cycle analysis showed that significant climate-benefits can be availed of, implying environmental sustainability, when the additional biogas is refined and used to replace fossil-diesel in public bus transport. Hydrochar-assisted anaerobic digestion of organic wastes may be posited as a technology which may entrench itself in the circular bio-economies of tomorrow, and by doing so, contribute to a set of sustainable development goals. While these were batch-digestion experiments, this part of the two-part series recommends more-realistic continuous-digestion experiments which incidentally form the focus of Part 2.

In Part 2 of the two-part series, single-stage anaerobic co-digestion in two continuously fed reactors replaced the batch process of Part 1. A life-cycle costing analysis was carried out to determine if, investing in a hydrothermal carbonization (HTC) system to produce hydrochar in-plant to augment biogas production will be economically feasible. Hydrochar addition resulted in a 59% rise in biogas yield (and 53.5% in methane yield). The study confirmed the techno-economic feasibility for coupling an HTC plant with a digester supplying 25% of the digestate it produces, to the former, as the raw material for hydrochar production. The rest of the digestate (rich in carbon, nitrogen, and phosphorus) can be used as fertiliser. Investing in an HTC plant contributing to a rise in methane production of 17% (or 53%) will result in a net profit of 363 million SEK (or 1237 million SEK) over a 20-year period. If the Karlskoga biogas plant decides to rely on purchasing hydrochar from the external market instead, the corresponding net profit will be 177 million SEK (or 1052 million SEK) over the same 20-year period, implying that a decision to integrate and interconnect is likely to be economically more feasible, in a circular bioeconomy in the future.

The potential of heterogeneous hydrochar-based catalysts as a desirable technology for biodiesel production is highlighted in this book chapter. These hydrochar-based catalysts have renewable features, are cost-effective, and have efficient catalytic properties, making them an excellent choice in the field due to their high carbon content and unique physicochemical features. This chapter aims to provide a comprehensive review of the feedstock of hydrochar from different biomass sources including agricultural waste, food waste, and forestry waste. The hydrochar production technologies and factors affecting the properties of hydrochar during production were also discussed. The catalytic performance to produce biodiesel can be considerably improved by the development of types of heterogeneous hydrochar-based catalysts via introducing active species such as metal nanoparticles or acid- or base-functional groups onto the hydrochar surface, and the parameters that influence biodiesel yield and selectivity during biodiesel production utilizing heterogeneous hydrochar-based catalysts were discussed. The multifaceted nature of hydrochar, combined with its renewable origin and distinctive physicochemical properties, positions it as a valuable resource for advancing sustainable and efficient catalytic processes. Finally, this chapter advances knowledge on heterogeneous hydrochar-based catalysts and encourages further research in this promising area while outlining current research and future directions.

As the aviation sector is experiencing phenomenal growth, the substantial demand for aviation fuel is also increasing. Synthesis of sustainable aviation fuel would help curb this enhanced demand while reducing greenhouse gas (GHGs) emissions. In this regard, bio-jet fuels have shown promising potential as they are renewable, release less CO₂ on combustion, highly compatible with aviation engines, and can be used without any modifications. Several researchers have exploited sustainable waste sources for bio-jet fuel synthesis by various conversion technologies, which utilize the principles of circular bioeconomy. This book chapter particulars on the aspects of circular bioeconomy along with the conversion technologies, advantages, and disadvantages of bio-jet fuel. Additionally, circular economy-based production of bio-jet fuel from various waste streams, as demonstrated by researchers are thoroughly reviewed. The various challenges to bio-jet fuel production and their possible solutions are assessed to facilitate the suitable implementation of a circular bioeconomy.

Due to its production from renewable feedstocks, usage as an alternative fuel, and favorable effects on the environment, bioethanol is one of the most intriguing biofuels currently on the market. It is currently mostly made using basic ingredients that contain sugar and starch. However, a variety of readily available lignocellulosic biomass feedstocks are used to produce bioethanol, including waste from forestry, agriculture, and the processing of cereals. The complex mixture of carbohydrates known as lignocellulose needs to undergo an efficient pretreatment practice in order to generate the pathways necessary for the synthesis of fermentable sugars, which are subsequently hydrolyzed and fermented into bioethanol. Renewable lignocellulosic raw materials are cheap feedstocks that do not take away market share from the food and feed sector, promoting sustainability despite financial and technological barriers. The procedures for bioethanol extraction and purification, as well as the creation of bioethanol from renewable raw materials, have also been covered. This paper examines the developments in the manufacturing of bioethanol as a fuel from a variety of renewable feedstocks, as well as the methodologies for purification and separation, prospects, and challenges.

The advancement of ecologically benign, renewable, and sustainable alternative energy sources is vital for the current global economic theories. The largest source of renewable energy, bioenergy podia advance the economy and the circular economy by serving as a strategic component. To fulfill the expanding demands of humanity, biomass materials such as agricultural products, alcohol fuels industrial waste, landfill gas, solid waste, and wood have attracted interest for use in the synthesis of biofuels. The energy generated from biomass is less harmful to the environment, inexpensive, readily accessible locally in great quantities, and offers job opportunities for employees in diverse global boundaries. Sustainability, the decline in emissions of greenhouse gases and an upsurge in manufacturing jobs are the benefits of using renewable sources to manufacture energy, chemicals, and fuels. These elements promote the development of local economic and social systems. The current chapter focuses on the availability of numerous waste biomass materials and their characteristics as viable renewable energy sources. The analysis also includes the current state of the world's energy supply, the need for sustainable alternative energy sources, established and developing technologies for biomass conversion, and the circular economy of waste biomass management. From the review, it is possible to infer that utilizing cost-effective sources for implementation in energy platforms and biofuels will increase the competitiveness of bio-based companies and boost the economics of existing value chains. Understanding the characteristics of biomass materials enables us to determine the best approach to use them for energy in the future and cut down on our reliance on fossil fuels.

The global issue of excessive food waste has raised significant concerns, underscoring the urgent need for sustainable interventions incorporating eco-friendly technologies. Around 1.3 billion tons of food are discarded every year, representing a one-third of the world total food production. This food wastage comes at a considerable cost to the world economy, estimated at around $750 billion. The escalating generation of food waste highlights the pressing need for effective measures to address this issue with a dual purpose. Utilization of food waste includes distillery waste, feed and poultry waste, oil processing waste, cooking oil waste, seafood waste, dairy waste, vegetable and fruit waste for production of various biobased products reducing economic losses and promoting sustainability by harnessing. This encompasses the utilization of diverse bioprocesses, including acidogenesis, fermentation, photosynthesis, solventogenesis, methanogenesis, bio-electrogenesis, and oleaginous processes, each capable of yielding a wide spectrum of valuable products. Within this book chapter, the primary emphasis on products, specifically bioelectricity, biodiesel, and biofuels, as crucial elements for achieving sustainability and advancing the objectives outlined in sustainable development goals (SDG)-12. SDG-12 leads to responsible consumption and production, particularly SDG 12.3, which aims to halve global per capita food waste. To ensure the economic viability of these bioprocesses and align with sustainable goals, it is imperative to adopt a biorefinery strategy that optimizes the utilization of residual organic waste for the recovery of a diverse range of green products within a circular economy framework.