Combustion characteristics of briquette fuels from sorghum panicle-pearl millets using cassava starch binder

Millet as a promising C4 model crop for sustainable biofuel production

The rapid depletion of conventional fuel resources and rising energy demand has accelerated the search for alternative energy sources. Further, the expanding need to use bioenergy crops for sustainable fuel production has enhanced the competition for agricultural land, raising the "food vs. fuel" competition. Considering this, producing bioenergy crops on marginal land has a great perspective for achieving sustainable bioenergy production and mitigating the negative impacts of climate change. C4 crops are dual-purpose crops with better efficiency to fix atmospheric CO2 and convert solar energy into lignocellulosic biomass. Of these, millets have gained worldwide attention due to their climate resilience and nutraceutical properties. Due to close synteny with contemporary C4 bioenergy crops, millets are being considered a model crop for studying diverse agronomically important traits associated with biomass production. Millets can be cultivated on marginal land with minimum fertilizer inputs and maximum biomass production. In this regard, advanced molecular approaches, including marker-assisted breeding, multi-omics approaches, and gene-editing technologies, can be employed to genetically engineer these crops for enhanced biofuel production efficiency. The current study aims to provide an overview of millets as a sustainable bioenergy source and underlines the significance of millets as a C4 model to elucidate the genes and pathways involved in lignocellulosic biomass production using advanced molecular biology approaches.

Characterization of solid biomass briquette biofuel from the wastes of Senna auriculata and Ricinus communis using Tapioca starch for sustainable environment

Biomass energy contributes nearly 14% of the total global energy. Therefore, biomass briquettes can be effectively considered an alternate source of fossil fuels. The present study aims at utilizing Senna auriculata and Ricinus communis waste generated locally for the production of biomass briquettes with 10% of tapioca starch as binder. The biomass wastes are blended at various proportions such as 0:100 (S1), 25:75 (S2), 50:50 (S3), 75:25 (S4) and 100:0 (S5) respectively, and the concentration of binder was maintained to be constant. The characterization of the prepared biomass briquettes includes the analysis of physical characteristics, proximate analysis, elemental analysis, SEM analysis, thermogravimetric analysis, differential scanning calorimetric analysis and XRD analysis. The results of the proximate analysis have revealed that the biomass briquettes possess lower percentage in terms of moisture content, ash content, sensible fixed carbon and high percentage of volatile matter content. Energy dispersive X-ray analysis has shown that the carbon and oxygen are the major elements for all the biomass briquettes. SEM analysis has revealed that the surface of the biomass briquettes is identified with irregular surface, lumps, cavities and few deposits of carbon particles. Thermogravimetric analysis and DSC analysis have reconfirmed the spontaneous burning characteristics of biomass briquettes. XRD analysis has proved that the bonding between each element present in the biomass briquettes is either monoclinic, tetragonal, orthorhombic or anorthic.

A review on the conversion of cassava wastes into value-added products towards a sustainable environment

The solid and liquid wastes generated from cassava-based industries are organic and acidic in nature, which leads to various global concerns-primarily global warming and biodiversity loss. But the conversion of these wastes into value-added products associated with environmental pollution control contributes to sustainable development. Generally, the thermochemical process such as pyrolysis and gasification and biochemical processes such as anaerobic digestion have been applied for the conversion of cassava waste into value-added products. This review addresses the valorization of cassava wastes, which fulfill almost all needs of the hour, such as energy (biofuel), wastewater treatment (adsorbents), bioplastics, starch nanoparticles, organic acid production, and antimicrobial agents. The major aim of this paper is to analyze and provide the disclosure of the efficiency of cassava-based industrial waste as a source to minimize the problem associated with conventional fossil fuels and through which mitigate the impact of global warming and climate change. Furthermore, recent research and achievements in the valorization of cassava waste have been highlighted.

Briquette production from a mixture of biomass: poultry slaughterhouse sludge and sawdust

This study refers to the development of hybrid briquettes using centrifuged sludge from the wastewater treatment of poultry and sawdust from furniture industry. The aim was to evaluate the performance of briquettes as a source of thermal energy, mitigating the risks of the current elimination and reducing the operational costs of their destination. To know the oxidizing characteristics of the briquettes and their mechanical resistance, superior calorific power, ash content, volatile materials, fixed carbon, and resistance to axial compression were evaluated. Thermogravimetric and differential exploratory calorimetry analyses were performed. Statistical treatments were carried out to verify the most significant factors to produce briquettes, the best proportions of the raw materials, and to evaluate whether there is interference from moisture and glue flour used as a binder. The best condition of the sludge-sawdust mixture was 15% and 85%, respectively, with 6.0% moisture. The best-case treatment had 23.82-MPa mechanical resistance, a calorific value of 17.20 MJ kg^-1, and a density of 1374.15 kg m^-3.

Upgrading of banana leaf waste to produce solid biofuel by torrefaction: physicochemical properties, combustion behaviors, and potential emissions

This study is the first report that focuses on investigating the effects of torrefaction on the bioenergy-related properties, combustion behavior, and potential emissions of banana leaf waste (BLW). Experiments were first conducted in a bench-scale fixed-bed reactor operating at light (220 °C), mild (250 °C), and severe (280 °C) torrefaction conditions to torrefy the raw BLW. Torrefaction pretreatments reduced the weight of the raw BLW by about 60%, but the resulting solid biofuel can preserve up to 77% of the energy content of the raw biomass. It was found that torrefied BLW contains more concentrated fixed carbon than the raw BLW, volatile matter content of up to 59.8 wt.%, and a higher HHV of up to 20.7 MJ kg^-1 with higher concentrations of carbon, nitrogen, and ash. Bulk density increased 13.0% over the raw BLW, and the torrefied BLW became a solid biofuel with 51.5% greater energy density under the severe torrefaction condition. The upgrading of BLW by torrefaction enhanced its combustion performance in terms of comprehensive combustion, ignition, burnout, and flammability indices. Compared with commercial hard coal, BLW torrefied at the mild condition (250 °C) had lower potential emissions per unit of energy, 25.3% less CO₂ emission, 3.1% less CO emission, 96.4% less SO₂ emission, and 18.4% less dust emission, except for NO_X emission. This study conclusively indicates that BLW after torrefaction has enhanced bioenergy-related properties, improved combustion performance, and reduced emissions potential, proving to be a promising method for its valorization.

Effect of compacting conditions on the viscoelastic properties of banana leaf waste and briquette quality

This study evaluated the effects of the temperature and pressure used when compacting banana leaves on viscoelastic properties and briquette quality. Banana leaves with 12.4% of humidity were milled at two ranges of average particle size. The briquetting was carried out in a cylinder-piston device coupled to a universal mechanical test machine, under different compacting temperatures (30 and 120 °C) and pressures (20, 40 and 60 MPa). Several parameters, including compacting module, porosity index, final density, critical density, compacting energy, compression ratio, higher heating value, and energy density, were investigated. The banana leaf particles smaller than 1.7 mm performed better during compaction, with low compacting resistance. Temperature showed less influence on final density than pressure. The increase of pressure contributed to decreasing the compacting module and to achieving denser briquettes. It was not necessary to apply high temperature to obtain briquettes with high final density and energy density. The optimum briquetting process parameters identified can be used to produce briquettes from banana leaves at an industrial scale with an extruder. Briquetting adds value to banana leaf waste and reduces environmental pollution.

A Review of Biomass Briquette Binders and Quality Parameters

The adverse effect of the use of fossil fuels on the environment and public health has given rise to a sustained renewable energy research and development. An important component of global renewable energy mix is the use of loose biomass, including agricultural and forestry residues, to produce solid fuels in the form of briquettes. Briquettes play a significant role in bioenergy mix in developing and developed countries. The production of biomass briquettes often entails the collection, transportation, storage, processing, and compaction of loose biomass that meet specific quality parameters. The densification process often involves the addition of binders to improve the cohesive strength of the briquette material. This paper surveys recent literature from 2012 to 2021 to establish the current state of research on the use of binders in briquette production; and reviews current parameters used in assessing the quality of biomass briquettes with focus on mechanical and handling properties. While a number of quality parameters were identified, their assessment methodologies varied widely in the literature, thus necessitating standardization for comparability purposes. The review also includes factors affecting the wide production and adoption of biomass briquettes in most developing economies and proposes ways of overcoming the bottlenecks.

Biomass valorization for energy applications: A preliminary study on millet husk

This study used millet husk which is a waste and gum Arabic as binder to develop briquettes for domestic cooking in Northern Nigeria. The objective was to investigate the effect of particle sizes, compaction pressures and binder concentrations on the physical, mechanical and thermal characteristics of the briquettes. Furthermore, the study also accessed the economic viability of the usage of millet husk briquettes as fuel. Particle sizes of 0.3, 0.4, 0.6 and 1.7mm; compaction pressures of 10, 15, 20 and 25 MPa and binder concentrations (gum Arabic) of 25, 30, 35 and 40% were used to densify the millet husk mixed with gum Arabic at room temperature with the aid of hydraulic press. The caloric value (15.27 MJ/kg) was determined using ASTM D2015, other physical and chemical properties of the millet husk was determined by proximate and ultimate analysis which showed that volatile matter (76%), ash content (6.5%) and sulphur content (0.3%) are within the recommended range for domestic cooking fuels. It was found that the density (438 kg/m³ and 669 kg/m³), impact resistance index (70–93%) and compressive strength of the millet husk briquettes increased with compaction pressures and binder concentrations and decreases with increase in particle sizes, while for porosity of the briquettes, the above case was a reversal. The performance of the briquettes for domestic cooking were accessed by ignition time (109 and 140 s); burning rate (0.09 g/s and 0.18 g/s) and water boiling test which took 5 and 11 min to boil 1 L of water as compared to fuel wood that takes longer. Economic analysis showed that utilizing the millet husk generated in northern Nigeria will lead to huge savings in fuel wood consumption, monetary savings of about ₦ 9,257,869,268.62, and reduction in deforestation and its attendant problems. A structured questionnaire as used to ascertain the acceptability of the produced briquettes. Most of the respondents (90%) in a survey expressed willingness to use millet husk briquette as replacement for wood. The study concludes that millet husk is good for briquetting for energy applications with high potential to reduce energy poverty, minimal waste and reduce indoor pollution for domestic cooking therefore, making millet cultivation more profitable in Northern Nigeria.

Combustion characteristics of biomass fuel briquettes from onion peels and tamarind shells

Rising worldwide demand and consumption of fossil fuels have elevated wealth creation, improved undesirable impacts on climatic change from emission of greenhouse gases, and endangered communal health. In developing nations, biomass wastes, which include but are not limited to agricultural residues, are generated in huge quantities yearly. During the disposal of biomass, incomplete combustion causes people to get exposed to elevated indoor concentrations on health-damaging pollutants including particulate matter and carbon monoxide. Inefficient usage or disposed biomass wastes may cause toxic impacts on higher levels of pollution, the consequent degeneration of public health and ecological contamination. It is possible to convert these wastes into energy-efficient briquettes through densification. In this research work, the combustion characteristics were identified from biomass briquettes which were produced from Onion Peels (OP), Tamarind Shells (TS) and Cassava Starch. OP-TS were mixed sequentially and conversely with different proportions. From the total weight of biomass, 10% of cassava starch was added and briquettes were produced under 200 kN pressure from the compressed hydraulic system within the dwell time of 60 seconds. The proximate characteristics such as the presence of water content, amount of fixed carbon, ash and volatile matter were determined by using the standard procedures of the American Society for Testing and Materials (ASTM). The ultimate parameter, which is inclusive of Carbon (C), Hydrogen (H) and Oxygen (O) were diagnosed in all produced biomass briquettes and calorific values were identified for all the produced biomass briquettes as well. OP-TS have better fuel properties in comparison with pine, cotton stalk (CS), wood sawdust (WS), municipal solid waste (MSW) and cotton straw biomass briquettes (CSB). Therefore, the produced biomass briquettes could bring substantial environmental and socio-economic benefits to rural communities and are potentially worthy fuels derived from agricultural wastes.