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Covalent Organic Frameworks-Based Adsorbents for Methane Storage:
Published in Tuan Anh Nguyen, Ram K. Gupta, Covalent Organic Frameworks, 2023
Methane is the smallest hydrocarbon but it has the power to drive a variety of machines covering a wide range from household equipment to rockets. The natural and anthropogenic origin of methane includes geological processes, biological practices, and industrial activities. Therefore, it exists in all the spheres of the earth; atmosphere, biosphere, lithosphere, and hydrosphere. Predominantly, it is produced in the hydrosphere by the anaerobic decomposition of organic matter and is stored as methane hydrates and clathrates in the cryosphere. Besides, biomass burning, coal mining, wetland methane emissions, ruminant and farm animals, permafrost areas, methanogenesis, rice cultivation, waste treatment, volcanic eruptions, industrial processes, etc. contribute to emerging the methane as the most dominant greenhouse gas in the atmosphere of the earth. Although the methane emission in the atmosphere is less than the carbon dioxide, however, its impact on global warming is far more than CO2 . The greenhouse effect is responsible for the increase in the levels of carbon dioxide and global warming. It is expected to produce the climate extremes such as floods, droughts, and enhanced temperatures thereby posing a threat to all the ecosystems that are slowly losing their balance [1].
Biomethane Production through Anaerobic Digestion of Lignocellulosic Biomass and Organic Wastes
Published in Sonil Nanda, Prakash K. Sarangi, Biomethane, 2022
Alivia Mukherjee, Biswa R. Patra, Falguni Pattnaik, Jude A. Okolie, Nanda Sonil, Ajay K. Dalai
Biomethane, or popularly known as biogas, is produced through both thermocatalytic and biological processes. However, the biological production of methane from several wastes and lignocellulosic biomasses is becoming popularized due to its potentiality towards the economical processing costs. Biological production of methane comprises several stages, which majorly depend upon the types of feedstock implemented for the methane production. Generally, this process of methane production is known as methanogenesis, which is mainly carried out in an anaerobic atmosphere by methanogens (methane-producing microorganisms).
Electro-Fermentation Technology: Synthesis of Chemicals and Biofuels
Published in Kuppam Chandrasekhar, Satya Eswari Jujjavarapu, Bio-Electrochemical Systems, 2022
Devashish Tribhuvan, V. Vinay, Saurav Gite, Shadab Ahmed
Methane is an important molecule that is primarily used as biofuel to make heat and electricity, and it is also a precursor of various chemicals. Methane is economical and has diverse applications in industries. Methane could be considered a powerhouse of energy (Hwang et al., 2018). Methanogenesis is the process by which methanogens produce methane by reducing carbon dioxide. Organic molecules like formate, acetate, and methylamine are used with CO2 and H2 as substrates for methane production. Even though the substrates are very simple, methane formation is a complex biochemical process that involves various coenzymes and genes. Methanogens are categorized into three groups according to the substrate used: acetolactic methanogens, hydrogenotrophic methanogens, and methylotrophic methanogens (Table 6.2) (Fu et al., 2021).
Methane, a renewable biofuel: from organic waste to bioenergy
Published in Biofuels, 2022
Mixtli J. Torres-Sebastián, Juan G. Colli-Mull, Lourdes Escobedo-Sánchez, Daniel Martínez-Fong, Leonardo Rios-Solis, María E. Gutiérrez-Castillo, Gloria López-Jiménez, María L. Moreno-Rivera, Luis R. Tovar-Gálvez, Armando J. Espadas-Álvarez
Methanogenesis is the last stage of anaerobic digestion in which the products of the previous steps are metabolized to methane. In contrast to the previous stages, the microorganisms that carry out methanogenesis belong to the archaea domain [14, 24]. Methanogenic archaea are strictly anaerobic and highly sensitive to oxygen [14] and also are highly sensitive to the physicochemical changes usually found in an anaerobic digester (pH changes, organic overloading, high salt, and total ammonia nitrogen), which can provoke an accumulation of VFAs and consequently the failure of the process [31]. In anaerobic digestion, methanogenesis can occur through 6 metabolic pathways: from acetic acid, methanoic acid, carbon dioxide, dimethyl sulfate, methanol, and methylamine. The following equations (equations 10 to 13) exemplify methane production from acetate, ethanol, carbon dioxide and formate [14, 24]. The pathway is called acetoclastic if the substrate is acetic acid, while if the substrates are hydrogen and carbon dioxide, the pathway is called hydrogenotrophic [32].
Biogas potential determination and production optimisation through optimal substrate ratio feeding in co-digestion of water hyacinth, municipal solid waste and cow dung
Published in Biofuels, 2022
Tawanda Kunatsa, Lijun Zhang, Xiaohua Xia
Complex biomass materials are broken down into simple monomers with the aid of enzymes in the hydrolysis stage. Starch hydrolysis is catalysed by a combination of amylase enzymes while cellulose hydrolysis is catalysed by cellulases such as exo-glucanases, endo-glucanases and cellobiases. Enzymatic hydrolysis of proteins is aided by protease and peptidases collectively known as proteinases. Lipid hydrolysis is facilitated by triglyceride lipases [41,42]. In acidogenesis, the monomers produced in hydrolysis (amino acids, simple sugars and fatty acids) are fermented and anaerobically oxidised by acidogenic bacteria. Intermediate products such as volatile fatty acids are anaerobically oxidised by acetogenic bacteria in the acetogenesis stage. In methanogenesis, methane is produced from the products of acidogenesis and acetogenesis with the aid of methanogenic bacteria. These biochemical reactions are interrelated and depend on each other as depicted in Table 1.
Trends in an increased dependence towards hydropower energy utilization—a short review
Published in Cogent Engineering, 2019
Girma T. Chala, M. I. N. Ma’Arof, Rakesh Sharma
Although the utilization of hydropower plant brings various positive impacts to the nation, the threats tangling the good cause should be taken into critical consideration. Nepal unstable topology due to active seismic activities causes the hydropower plant to be well planned to mitigate environmental impact (Sharma & Awal, 2013). Most Himalayan Rivers contain huge quantities of sediment with hard abrasive particles. The region’s climate and tectonic conditions as well as human activities are highly conducive for erosion and sedimentation. Brazil generates around 70% of its electricity from hydropower and still has an enormous hydroelectricity potential to be developed in the Amazon Watershed. However, its flat geology, large storage reservoirs make it impractical in the Amazon region (Hunt et al., 2016). After flooding in the hydro station, a considerable quantity of organic matter stays under water which, in the presence of oxygen, is decomposed and produces carbon dioxide. Conversely, in the absence of oxygen, the organic matter is decomposed and produces methane gas (through methanogenesis) with a global warming potential 21 times higher than carbon dioxide (Briones Hidrovo et al. 2017). Moreover, rivers commonly transport organic matter which contributes, with its concentration at the reservoir, to a continuous decomposition and production of the greenhouse gases (GHG). Thus, as the amount of flooded organic matter increases, GHG emissions also raise up.