Microbial Biotechnology for Bioenergy

Microbial Biotechnology for Bioenergy presents the new and emerging biotechnological and microbiological approaches in bioenergy and their economic, social, and environmental implications. Using the latest global data and statistics, it analyses how bioenergy technology improves quality of life by reducing air and water pollution and mitigates energy dependence by creating renewable resources in local communities.

The book is formed of three sections; Section 1 addresses the “Sources, Challenges, and Environmental Views of Bioenergy and includes an overview of bioenergy, global statistics and projections for future bioenergy development, the role of biotechnology and bioprocesses in bioenergy, feedstock sources, challenges, decarbonisation, and emerging innovations and technologies. Section 2 “Yesterday, Today, and Tomorrow: Innovations of Bioenergy examines the vast topics of biotechnology and microbiology for bioenergy, reviewing both the present day state-of-the-art and future potential. Readers will find dedicated chapters on bioconversion of biomass energy and biological residues, the role of microbes, the potential of organic waste to provide bioenergy, the biotechnology of biofuels such as bioethanol, biodiesel, and biohydrogen, the sustainability of cellulosic ethanol energy and artificial photosynthesis, Power-to-X and integrating energy storage innovations, and the sustainability of microbial fuel cells. Finally, Section 3 explores the policies and environmental aspects of bioenergy, providing a global perspective on the current and future impact of bioenergy, including global projections based on present day global statistics.

Microbial Biotechnology for Bioenergy is a valuable reference for biotechnologists, environmental engineers, and microbiologists interested in bioenergy, and includes explanations of the fundamentals and key concepts to ensure it is accessible to students as well as researchers and professionals.

• Critically reviews past, present, and future bioenergy technologies, including global statistics, policies, and emerging approaches
• Highlights opportunities to improve quality of life and mitigate energy dependence, reducing air/water pollution and creating renewable resources in local communities
• Explores environmental benefits of incorporating microbial remediation into bioenergy production

• Language: English
• Publisher: Elsevier Science
• Release date: Mar 8, 2024
• ISBN: 9780443141133

Book preview

1

Sources, challenges, andenvironmental views

Outline

Chapter 1 Microbial biotechnology for bioenergy: general overviews

Chapter 2 Global advances in bioenergy production technologies

Chapter 3 Role of biotechnology and processing in bioenergy

Chapter 4 Distribution of biomass sources for bioenergy production: challenges and benefits

Chapter 5 Decarbonization and the future fuels

Chapter 6 Bioenergy: the environmentalist’s perspectives

Chapter 1

Microbial biotechnology for bioenergy: general overviews

Sesan Abiodun Aransiola¹, ², Oyegbade Samuel Adeniyi³, Isibor Patrick Omoregie³, Fadekemi O. Akinhanmi³, Margaret I. Oniha³ and Naga Raju Maddela⁴,    ¹Department of Microbiology, Faculty of Science, University of Abuja, Abuja, Nigeria,    ²Bioresources Development Centre, National Biotechnology Development Agency (NABDA), Ogbomoso, Oyo State, Nigeria,    ³Department of Biological Sciences, Covenant University, Ota, Ogun State, Nigeria,    ⁴Departamento de Ciencias Biológicas, Facultad de Ciencias de la Salud, Universidad Técnica de Manabí, Portoviejo, Ecuador

Abstract

Bioenergy technologies are environment-friendly, renewable, and a clean way of powering the global community. Bioenergy technology is an innovation that improves the quality of life by simply reducing water and air contamination; this also mitigates energy dependence through creation of renewable resources locally. Bioenergy sources include wind, water, geothermal, nuclear power, solar, and natural gases. The most interesting and important part of bioenergy is the environmental benefits as part of a global energy future, which are aided by microorganisms. The future of bioenergy, however, seems bright because recent global information in this field proved that more renewable energy capacity has been fixed globally than new fossil fuel and nuclear capacity combined. As the global population progressively increases, there is an ever-increasing demand for clean energy. The only safe answer to this is sustainable energy, which will protect the earth from climate change and make it a good habitat for all living organisms. This chapter provides a general overview to microbial biotechnology for bioenergy, sources, and challenges of bioenergy, role of microorganisms in bioenergy generation, innovations in bioenergy, and the environmental conservation of bioenergy.

Keywords

Bioenergy; environment; contamination; renewable energy; biotechnology

1.1 Introduction to bioenergy

Bioenergy is a pure resource that can be generated indefinitely, unlike petroleum-derived fuels, which are significant pollutants of the air, land, and water. Biomass is a plentiful source of neutral carbon that can be used to create heat instead of fossil fuels without upsetting the delicate equilibrium of the air in the atmosphere (Phong Mai & Quan Nguyen, 2021). Biomass is comprised of living things and recent deaths. Living things that have already been transformed into fossil fuels are not included in this. Waste is an unused facility that produces energy by burning in the field of energy production. Global emphasis is now focused on manufacturing eco-friendly and limitless biofuels from waste as a result of an increasing need for fossil fuels and its associated environmental issues, such as increasing temperatures (Singhania, Patel, Pandey, & Ganansounou, 2017). Renewable energy is a form of sustainable energy produced from naturally occurring biological sources, including plants, waste from animals, water treatment, and so forth. Many academic and research institutions throughout the world are working to develop new bioenergy technologies, particularly in the area of biofuels (Whitlock, 2015). Utilization of all other types of fuels decreased in 2020, while usage of green power increased by 3%. Among the numerous other industries using green energy, the usage of bioenergy grew by 3% (Duarah et al., 2022). The most popular renewable energy sources are solar, bioenergy, wind, geothermal, and hydropower (Singh et al., 2022). The overall demand for energy from renewable sources increased significantly (15.1 exajoules, EJ) from 2009 to 2019 at a rate of about 4.4% year. Bioenergy offers an attractive substitute to fossil fuels that is thought to support a healthy economy, effective energy usage, safeguarding of the nation’s energy independence, and a decrease in the emission of carbon dioxide and other greenhouse gases (Duarah et al., 2022). Some sources of renewable energy can be used to generate heat, but not for electricity or mobility. For instance, solar energy works well in local or areas where there is sunlight, but wind power is suitable for coastal places. Similar to how each green power source has a unique performance profile, hydropower, geothermal, and ocean thermal energies are all viable in some situations. The optimum choice depends on the location, use, and time of year. Due to a constant supply of the raw material, biomass, which contributes to large-scale use with a low carbon impact, biofuel is one of the most widely used forms of renewable energy (Volli, Gollakota, Purkait, & Shu, 2020). Biomass burning has always been the most direct and straightforward method of generating energy. Traditional biomass burning, such as wood, coal, straw, and ash, often produces smoke, dust, vapors, volatile substances, and dangerous gases due to unfinished reactions forced by duct gases (Phong Mai & Quan Nguyen, 2021).

By 2060, it is anticipated that advanced biofuel usage would outweigh traditional bioresource usage, increasing the generation of biofuels from its current level of 56 EJ to 145 EJ (Scarlat & Dallemand, 2019). In consideration of this, a number of crops, algae, and lignocellulosic biomass are regularly recommended for energy cultivation. Woody plants, grass/herbal crops (permanent plant), starch-based crops, and oleaginous seeds are appropriate for generating energy (Abdul Malek, Hasanuzzaman, & Rahim, 2020). Globally, the use of green power increased significantly; in 2014, it made up 19.2% of all final energy usage. The percentage of electricity generated worldwide grew by 26% in 2018. The COVID-19 pandemic in 2020, however, has a significant impact on productivity (Duarah et al., 2022). From 8.5% in 2005 to almost 17% in 2015, the European Union’s use of solar energy has increased dramatically. Biomass-derived energy is being used more and more, especially in Asia. Before 2000, the proportion of bioenergy in the overall primary energy use of the world remained constant at almost 10% (Scarlat, Dallemand, Hjelme, & Lien, 2018). In the nations that make up the Association of Southeast Asian Nations (ASEAN), there is a very sharp increase in the need for biofuel. The ability of China to produce ethanol has reportedly increased recently.

ECOWAS have also set some targets aiming to use 10% of bioethanol and 5% of biodiesel in vehicles by 2030 and 2020. The utilization of bioenergy is expanding fast in nations other than those indicated above. The usage of bioenergy has greatly increased in Asian nations such as Japan, Malaysia, South Korea, Indonesia, and India (Duarah et al., 2022). The development of biofuels involves sociological, ecological, and economic challenges, even while it opens up new options for using various wastes as feedstock. It is unclear how well bioenergy compares to fossil fuels in terms of decreasing emissions of greenhouse gases due to the wide array of materials that are used, the extensive array of bioenergy processes, and their level of complexity, especially if change in land use is a factor (Mata, Caetano, Costa, Sikdar, & Martins, 2013). When indirect consequences are taken into account, such as changes in indirect land use, the influence on livestock and food supplies, the nearby energy supply, biomaterials, and so forth, there are more uncertainties. Given the unique properties of biofuels, which are related to other markets, generated in enormous quantities, and involved in a variety of complex trade patterns, developing an environmentally beneficial system will be highly challenging. In order to maintain the sustainable future of global renewable energy potential, several governments have proposed various laws to be complied with bioenergy. According to Dragon et al. (2020) and Mak et al. (2020), these policies aim to strengthen bioenergy through environmentally sustainable practices. With the usage of sustainable biofuel, the social, economic, and ecological conditions of humanity are expected to improve. In order to promote the growth and viability of the bioenergy sector, various governments all over the world have established policies. Policies in several nations support the production of domestic feedstocks and cutting-edge biofuel feed technology. However, in their efforts to meet biofuel mandates and blending targets, the majority of governments are neglecting fundamental environmental challenges. The fundamental challenge for all nations is a lack of sufficient land for agriculture and feedstock.

1.2 Sources and challenges of bioenergy

The sources and forms of bioenergy production depend largely on the utilized base material or feedstock (Vassilev & Vassileva, 2016). Feedstock is mainly biomass that can be utilized to generate biofuels such as liquid (biodiesel, biobutanol, and bioethanol) and gaseous renewable fuels (biomethane, biohydrogen, and biogas) (Silvello et al., 2022). The earthly abundance of biomass enhances it as a common source of sustainable renewable energy production. Biomass contributes greatly to the foremost energy need in developed and third-world countries as the fourth largest source of energy in the world (Cano, Gomaa, & Jurado, 2023). Plants, edible and nonedible, are the predominant biomass source when it comes to renewable energy. Biomass can be depolymerized into fermentative sugars for the generation of biofuels using enzymatic hydrolysis of lignocellulose, resulting in a more commercially viable conversion process (Shields-Menard, Amirsadeghi, French, & Boopathy, 2018). Several biological, physical, and thermal processes can be utilized for biomass conversion into various kinds of renewable fuels or bioenergy. Some of these processes include direct combustion, hydrothermal liquefaction, anaerobic digestion, thermal gasification, pyrolysis, fermentation, and transesterification (Akindolire, Rama, & Roopnarain, 2022).

Generally, diverse biofuels are categorized into four generations determined by the type of utilized base material (Table 1.1), namely, first-, second-, third-, and fourth-generation renewable fuels (Alalwan, Alminshid, & Aljaafari, 2019). The first-generation (1G) biofuels were produced from high-energy traditional food crops like soybean, wheat, sorghum, sugar beet, sugarcane, and corn. However, the utilization of edible crops as feedstock-initiated dialogs concerning their implication on food availability, food security, and land use globally (Aransiola, Victor-Ekwebelem, Leh-Togi Zobeashia, & Maddela, 2023; Singh, Chakravarty, Pandey, & Kundu, 2018). The development of second-generation (2G) renewable fuels was stimulated by the limitation of 1G-biofuel output. The quest for new and sustainable approaches resulted in the utilization of nonedible feedstock such as lingocellulosic biomass derived from agricultural and industrial residues (Lakatos et al., 2019). However, cost implications and technological limitations regarding pretreatment challenges, biomass intractability, and the extraction of lignin still impede the stabilization of commercialized 2G bioenergy (Silvello et al., 2022). Microorganisms such as microalgae, actinomycetes, yeast, and fungi also represent biomass sources for 3G and 4G biofuel production (Alalwan et al., 2019). More recently, promising alternatives are being explored by the presentation of genetic manipulation of microorganisms to improve the yields of biomolecules which can lead to more biofuel production, known as fifth-generation (5G) biofuels. Genetic engineering can be used to alter plants and microorganisms to stimulate metabolic cellulose and hemicellulose channels for increased bioenergy production.

Table 1.1

1.3 Role of microorganisms in bioenergy generation

The creation of energy from matter is known as oxidoreduction, which is the basic feature of life (Gupta, Gupta, & Singh, 2017). Globally, there is a huge concern associated with increasing energy demand resulting from ever-rising human population and industrialization with consequent limited supply of conventional energy resources and quick depletion of nonrenewable fossil fuels. The need to meet the energy demands of the rising population and quell the daunting environmental issues including greenhouse gas emissions, global warming, and air pollution have necessitated the fervent exigency to investigate alternative renewable fuels (Ramamurthy et al., 2021). Utilization of microbes has attracted a lot of interest in the transformation of chemical energy in organic compounds to electrical energy. Microbial versatility and utility in renewable energy fuels production from differential living and biomass substrates will aid in greatly mitigating the aforementioned portentous issues, including numerous microorganisms that facilitate the transformation of carbohydrates into alcohol (Ramamurthy et al., 2021). In addition to their contribution to sustainable development, biomass as an energy source is mostly available at the local level and low initial costs are required for their conversion to biofuel (Rather et al., 2022). Bioenergy is a renewable form of energy produced from biomass, which comprises of biological materials produced directly and indirectly by photosynthesis including wood, wood and harvest residues, purpose-grown crops and organic waste from our homes, businesses, industries, landscape management, and farms. The biomass is converted to solid, liquid, or gaseous fuel, which can be employed in the production of heat and electricity for fueled transportations (International Energy Agency IEA, 2023). Bioenergy is normally produced from biological processes (fermentation or anaerobic digestion) through the use of effective and suitable microbial system and sustainable raw substrates (agricultural crops biomass residue and microalgae or biological wastes) (Srivastava, 2019).

Besides photosynthesis, different microorganisms that include cyanobacteria possess the ability to decompose water into the desired oxygen and hydrogen with some others being able to directly produce hydrogen through anaerobic processes (Agyekum, Nutakor, Agwa, & Kamel, 2022). Others can convert classic environmental pollutants into very significant potent energy compounds (methane and alcohol) (Teng, Xu, Wang, & Christie, 2019). The genotypic and phenotypic traits of diverse microbial strains can direct the generation of energy products to more excellent and efficient technologies and environmental purifiers (Fabris et al., 2020). The buildup of agronomic and industrial wastes in the fields leads to harmful environmental issues. Currently, bioenergy is the primary source of renewable energy today that contributes to energy for power generation and heat for industry and buildings as well as transportation (International Energy Agency IEA, 2023). Microorganisms exhibit significant roles in the industrial processing of different numerous products including the generation of bioenergy, which encapsulates bioethanol, biodiesel, biohydrogen, and bioelectricity. Heterogenous microbes including bacteria, fungi, yeasts, and microalgae, among others, are employed in the production of biofuels and bioenergy by amassing intracellular lipids (primarily triacylglycerol) into a huge amount of their biomass (Al Makishah, 2017). Ecological and economic benefits offered through biotechnological application of organic wastes via microbial activity include limitation of fossil fuel consumption, reduction of polluting emissions, facilitation of production of cost-effective raw materials, and the development of suitable substrates for diverse microorganisms (Al Makishah, 2017). Microbial biotechnology is a main strategy for sustenance of bioprocesses, in which microorganisms and their enzymes are employed in the conversion of carbohydrates, lignins, and glycerols into a variety of renewable resources such as bioenergy production. Application of microbes in the production of improved biomass products has been significantly recognized to reduce the expensive, toxic, and nonrenewable synthetic products and also based on the different microbial metabolic multiplicity that facilitates the production of biofuels from different moieties/substrates (Ramamurthy et al., 2021) such as the conversion of sugars to ethanol by majority of bacteria and utilization of plant-driven substrates by cellulolytic microorganisms (Kumar & Kumar, 2017). Further, Kumar and Kumar (2017) reported that methanol is produced from the utilization of methane by methanotrophs and reduction of atmospheric CO2 into biofuels by the photosynthetic potential of cyanobacteria and microalgae. These methanotrophs include Methanosarcina, Methanobacterium, Methanobrevibacter, Methanobacteriales, Geobacter sulfurreducens, and Shewanella oneidensis.

Different microbially synthesized biochemical products use the electrosynthetic technique as a way for bioremediation of wastewater and generation of electricity. This novel process employs the combination of both electrochemistry and microbiology with greater cynosure on its principles and challenges. Studies have published that bioelectrochemical cells (BECs) have attracted significant interest in bioenergy generation from organic biomass and wastewaters. Both microbial fuel cells (MFCs) and microbial electrolysis cells have been extensively employed for bioelectricity and biohydrogen production (Dai, Yang, Liu, Jian, & Liang, 2016; Logan et al., 2015) based on a similar mechanism of action where BECs (with unique characteristics called exoelectrogens or electricigens) show a specific molecular machinery, which transfers electrons from the microbial outer membrane to the conducive surfaces with subsequent generation of electricity and hydrogen from the electrons (Kracke, Vassilev, & Krömer, 2015). The exoelectrogens exhibit specific redox proteins/molecules that help the transfer of electrons from the microbial outer membrane to the electrode surface (Kracke et al., 2015). Microorganisms produce, accumulate, and secrete some biologically active molecules that include sugars, lipids, amino acids, and phytohormones for maintenance of soil viability and plant growth (Singh, 2015). Yeasts are the some of the efficient fermenting organisms utilized in ethanol production from biomass for lengthy duration. The large amount of lipids accumulated by cyanobacteria are important in biodiesel production. Furthermore, microbes also release gases as byproducts including hydrogen for the generation of gaseous biofuels and may be an alternative to natural gas. In bioethanol production, cane molasses or enzymatically hydrolyzed starch (Scully & Orlygsson, 2015) is primarily used for industrial or large-scale ethanol production by the fermentation activity of yeasts (Saccharomyces cerevisiae and Kluyveromyces marxians) and bacteria (Zymomonas mobilis). Additional processes that consist of pretreatment, hydrolysis, saccharification, and fermentation are required in the conversion of cellulosic biomass into ethanol. For the production of biodiesel, cyanobacteria members, Mucor circinelloides and Mortierella isabellina, among other microbes, due to their ability to store high lipid contents, have been used instead of different vegetable oil sources (Kumar, Kausha, Saraf, & Singh, 2018).

Different bacteria such as Klebsiella, Enterobacter, and Clostridium have been screened for the production of alcohols from glycerol (Kumar et al., 2018), and successful reports of anaerobic and aerobic conversions by Escherichia coli were published by Dharmadi, Murarka, and Gonzalez (2006) and Durnin et al. (2009). Cyanobacterial biophotolysis of water or photofermentation of organic substrates from photosynthetic bacteria is responsible for biohydrogen production (Hankamer et al., 2007). Cyanothece sp. ATCC 51142 is a cyanobacterium with the capacity to generate high levels of hydrogen under aerobic conditions (Bandyopadhyay, Stöckel, Min, Sherman, & Pakrasi, 2010), and its wild-type, Cyanothece sp. 51142, has been reported to produce hydrogen at rates as high as 465 L mol/mg of chlorophyll/h in the presence of glycerol. In a report by Wu et al. (2005), it was stated that anaerobic organisms such as acidogenic bacteria produce biohydrogen through dark fermentation from organic substances, thus serving as a better strategy for reducing excess organic waste. Other microorganisms including thermophilic microorganisms (Caldicellulosiruptor saccharolyticus and Thermotoga elfii) are also known for high hydrogen yields (Kumar et al., 2018). In a MFC, an active microbe is used as a catalyst in an anaerobic anode compartment instead of metal in a typical fuel cell. The active microbe (biocatalyst) in the anode chamber generates electrons and protons through oxidation of organic substrates, followed by the movement of protons to the cathode chamber through the proton exchange membrane, while the electrons are transported through the external circuit (Kumar et al., 2018). Common microorganisms including Geobacter, Shewanella, Pseudomonas, Clostridium, and Desulfuromonas have been fed into MFCs for electricity production, and they possess the ability to oxidize acetate, ethanol, lactate, and butyrate or propionate as a substrate (Kumar et al., 2018).

1.4 Challenges of bioenergy

Biofuels are renewable and environment-friendly sources of bioenergy with the necessary features to overcome the limitations associated with fossil fuels while concurrently reducing greenhouse gas emissions. As a result, a variety of bioenergy sources are currently being developed and implemented on a global scale to address the issues of deficient nonrenewable fossil fuel-based energy sources and achieving net zero carbon emissions (Rai et al., 2022). However, the positive projections and relevance of bioenergy production still face some challenges associated with the development and utilization of bioenergy. Bioenergy generation using biomass comes with associated risks such as latent or incidental effects of biofuels on land use that may cause significant alterations in the amount of carbon stored on land worldwide (Ranđelović & Pandey, 2023). First-generation biofuel production resulted in extensive utilization of agricultural lands, land-use alteration, adverse effects on biological diversity, threats to food security, and emission of pollutants such as carbon dioxide (CO2). Although second-generation biofuels were generated from inedible plants, their production also necessitated vast agrarian fields to cultivate oil-producing crops, which could compete for space for food crop cultivation. Microalgal-based (third generation) biofuels, which require no agricultural lands, also have challenges to surmount for the incorporation of their use as a renewable energy source (Khan et al., 2023). Low biomass efficiency, poor biomass separation, and insufficient technology hinder the production of microalgal biomass from being scaled up industrially (Costa, Freitas, Moraes, Zaparoli, & Morais, 2020). Technological developments in cultivating, harvesting, and microalgae biomass extraction are necessary to reduce production costs and improve downstream processes. Recent years have seen an increase in the generation of biodiesel and biogas through the genetic manipulation of yeast and microalgal biomass. However, there are technical obstacles that must be surmounted to mass manufacturing and competition of biofuels possible on an industrial scale.

Although some genetic editing technologies have demonstrated encouraging outcomes in laboratory testing, scaling up these techniques to exceptionally high yields and productiveness without losing performance is a significant barrier to commercialization (Manikandan et al., 2023). Perhaps for this reason, there has not been any convincing proof of this method’s commercial success despite enormous investment. Furthermore, bioenergy is said to be very complex. It is reportedly the only renewable energy source mainly used across all the energy fields (transport, heat, and electricity) and the only one that requires constant use of fuel with expensive supplies compared to solar and wind sources, which are readily available (Rasool & Hemalatha, 2016). Additionally, the energy output from burning biofuels is lower than that of fuels derived from petroleum, necessitating the use of larger quantities of biofuels.

1.5 Innovations of bioenergy

According to Kucharska et al. (2018), both conventional and modern biofuel makes up 9.5% of the world’s principal energy sources today, but it will only make up a minor percentage of the worldwide energy mix in 2100. In the future decades, there will undoubtedly be a surge of need for woody biomass as governments and power sector assets attempt to maintain coal-fired systems by shifting toward alternative coal. Wood pellet output for energy from biomass more than quadrupled to 26 million tons (metric tons) between 2006 and 2015. About half (47.7%) of the green power utilized in the European Union comes from solid bioresources, of which 40% is used to heat homes. New bioenergy markets in East Asia are expanding swiftly as well and may soon surpass European demand. For example, Obayashi (2017) claimed that 40% of the 11.5 GW of biomass generating projects that the Japanese government has authorized might be fueled by palm oil. In regard to biofuels, the globe will generate 142 tons in 2040 compared to 82 million metric tons of oil equivalent in 2017. Indonesia has fallen well short of its lofty objective of attaining biodiesel blends, while only employing 35% of its present capacity for refining palm oil (Reid, Ali, & Field, 2020). This implies that production might rise substantially without necessitating a big increase in expenditures. Reid et al. (2020) claimed that the combined need for biofuels from these new developing markets could hasten deforestation and raise CO2 production from some of the world’s last remaining intact forests due to mobility.

By switching to more established, highly energy-intensive biofuel carriers, the problems related to biomass logistics, commerce, and end usage can be solved. In this context, technologies like pelletization, torrefaction (for solids), and pyrolysis (for biooil) can be quite useful. As the generation of variable renewable energy rises, such energy carriers can aid in the massive amounts transformation of petroleum and coal to biomass and support network stability. As the supply of renewable energy rises, hybrid plants that use RE energy to make hydrogen for other biofuel plants and convert CO2 flow into biofuels or renewable energy sources based on the source of CO2 are also made possible (Benetti, 2018).

Both thermochemical and biochemical conversion techniques will be used to produce biofuels such as ethanol, methanol, and FT diesel directly in the next 10 years. In addition, pyrolysis and hydrothermal liquefaction will be used to create intermediates such as biooils from feedstocks with a high moisture content. As part of an interconnected bioenergy process to a value chain for fossil refineries, such intermediates will mostly be converted into drop-in biofuels using methods emulating refineries. Over the next 10 years, the key advancements in bioenergy are anticipated to result from both the development of technologies that are presently being tested or piloted as well as the invention of new ones that may one day reach this stage (Benetti, 2018). The list of recent technological developments in biofuels is as follows:

1.5.1 Gasification

With the aid of gasification technology, dried biomass feed is broken down into gas at temperatures ranging from 800°C to 1500°C and pressures ranging from 0.1 to 4 MPa. By transforming biomass into combustion-safe gas, it is a secondary combustion of both solid and liquid biomass. To reduce the amount of hazardous gases and dust produced by typical burning, gasification is considered. In order to create 38,000 m³ of ethanol or a volume corresponding to methanol, the Edmonton RDF gasification facility in Edmonton, Canada, implemented the final stage of methanol conversion in 2017 (Benetti, 2018). Biomass gasification can reduce the amount of pollutants released.

1.5.2 Biocoal

Fossil fuels are being replaced with biocoal. It is produced by heating biomass in an inert environment to either produce coal or torn wood, subject to the combustion temperature. Biofuels have many benefits over untreated biomass, including homogeneity, a high energy content (23 MJ/kg) comparable to fossil fuels, and low moisture content. These biomass materials can be consumed in coal-fired power plants, unlike other biomass kinds like wood chips. The best material is wood; however, other materials like straw, bones, and soil can also be utilized. From gases like CO, CO2, and hydrogen, biomass carbonization also creates pyrolysis oil. It can also be used as fuel, and in the future, biomass transport fuels may be made from it (Whitlock, 2015).

1.5.3 Algae

Globally, more algae are being produced for the production of biodiesel and other biofuels. One of the key benefits is that it can be grown with salt and wastewater without having a large negative influence on freshwater resources. Algae is biodegradable and has a high flash point, so if there is a spill, it will not harm the environment. The U.S. Department of Energy estimates that the replacement of oil by algae fuel requires only about 0.22% of the U.S. land area or about half of Maine’s land area, despite the fact that it is more expensive per unit than other second-generation biofuels due to high capital and operating costs (Whitlock, 2015).

1.5.4 Biocube

A particular kind of biodiesel microrefinery is the biocube. A 20-foot shipping container that has been specially converted houses the biodiesel processor. It is easily transported by road, rail, and sea because it weighs 3.5 tons. Chemical feed oil is put into the apparatus, such as specific vegetable oils, and biodiesel is produced in 1 hour. It is also capable of producing its own biodiesel-powered grid electricity. Once it has been prepared, biodiesel can be placed on any current diesel engine without the owner needing to pay for costly upgrades. By supplying biodiesel, it may be utilized both indoors and off-grid and can aid in a community or business’s quest for energy independence. It has a 250-liter-per-hour output and is readily operated using a Siemens touch screen panel built inside the containers. Glycerin and mulch, two byproducts of biocube, are used in anaerobic digestion, or they can be combined with other fuels or fertilizers (Whitlock, 2015).

1.6 Bioenergy and environmental conservation

Bioenergy refers to the conversion of organic materials, such as biomass and biogas, into usable energy forms (Leh-Togi Zobeashia, Aransiola, Ijah, & Abioye, 2018; Zhou, Clark, Nair, Hawkins, & Lambert, 2015). It plays a crucial role in the energy sector due to its renewable nature and potential to reduce greenhouse gas emissions. Bioenergy encompasses various forms, including biofuels for transportation, biomass for heat and electricity generation, and biogas from anaerobic digestion (Acheampong, Ertem, Kappler, & Neubauer, 2017). By utilizing organic waste materials and energy crops, bioenergy offers a sustainable alternative to fossil fuels, mitigating climate change impacts and reducing dependence on finite resources (Blanco-Canqui & Wortmann, 2017). Its importance lies in providing a cleaner and more sustainable energy source, promoting energy security, and contributing to the transition toward a low-carbon economy (Austin, Wickings, McDaniel, Robertson, & Grandy, 2017).

Environmental conservation refers to the protection, preservation, and sustainable management of natural resources and ecosystems (Bajwa, Peterson, Sharma, Shojaeiarani, & Bajwa, 2018). It involves efforts to conserve biodiversity, mitigate climate change, protect water and air quality, and promote sustainable land use. Environmental conservation is significant because it ensures the long-term survival and well-being of both human and nonhuman life on Earth. It helps maintain ecological balance, supports the provision of ecosystem services, such as clean air and water, and preserves natural habitats for future generations (Chen, Ale, Rajan, & Srinivasan, 2017; Demissie, Yan, & Wu, 2017). Additionally, environmental conservation is crucial for mitigating the impacts of climate change, preserving cultural and historical heritage, and promoting a harmonious relationship between humans and the natural world (Cooney et al., 2017).

1.7 Environmental benefits of bioenergy

Bioenergy offers several environmental benefits, making it a viable and sustainable energy solution. Some key environmental benefits include greenhouse gas emission reduction, climate change mitigation, renewable energy source, waste reduction and circular economy, reduced dependency on fossil fuels, rural development and job creation, and land restoration and biodiversity conservation (Correa, Beyer, Possingham, Thomas-Hall, & Schenk, 2017).

1. Greenhouse gas emission reduction: Bioenergy significantly contributes to reducing greenhouse gas emissions compared to fossil fuels. When organic materials are converted into biofuels, biomass, or biogas, the resulting energy releases carbon dioxide, but this carbon is part of the natural carbon cycle. It does not introduce additional carbon into the atmosphere, unlike fossil fuels. As a result, bioenergy helps mitigate climate change by curbing greenhouse gas emissions, hence mitigating carbon footprint (Homagain, Shahi, Luckai, & Sharma, 2015).

2. Climate change mitigation: By displacing fossil fuels, bioenergy plays a vital role in reducing the use of carbon-intensive energy sources. This shift contributes to mitigating climate change impacts by lowering overall carbon emissions and helping achieve national and international climate targets.

3. Renewable energy source: Bioenergy is derived from renewable organic materials, such as agricultural residues, dedicated energy crops, and organic waste. These materials can be continually replenished through sustainable practices, ensuring a continuous supply of renewable energy (Tonini, Hamelin, Alvarado-Morales, & Astrup, 2016).

4. Waste utilization and circular economy: Bioenergy promotes the utilization of organic waste materials that would otherwise end up in landfills or be left to decompose, emitting greenhouse gases. By converting these waste materials into biofuels or biogas through processes like anaerobic digestion, bioenergy helps close the loop in the circular economy, reducing waste generation, and utilizing resources more efficiently (Harris, Spake, & Taylor, 2015).

5. Reduced dependency on fossil fuels: Bioenergy offers an alternative to fossil fuels, reducing dependence on finite and depleting resources. By diversifying the energy mix, bioenergy contributes to enhancing energy security and reducing geopolitical risks associated with fossil fuel dependence (Hejazi et al., 2015; Immerzeel, Verweij, van der Hilst, & Faaij, 2014).

6. Rural development and job creation: Bioenergy production often occurs in rural areas, providing opportunities for local economic development and job creation. It fosters entrepreneurship, supports agriculture and forestry sectors, and helps revitalize rural communities through sustainable energy practices (Dias et al., 2017; Drewniak, Mishra, Song, Prell, & Kotamarthi, 2015).

7. Land restoration and biodiversity conservation: Sustainable bioenergy production can be integrated with land restoration efforts, such as reforestation and afforestation programs. These initiatives help increase carbon sequestration, restore degraded land, and enhance biodiversity conservation. By utilizing marginal lands for energy crop cultivation, bioenergy can minimize the pressure on valuable agricultural areas, safeguarding food production (Deng, Koper, Haigh, & Dornburg, 2015; Hoekman, Broch, & Liu,