Fig 7
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The development of biomass fuels to replace fossil fuels is on the rise, with increased bioenergy research on spent coffee grounds (SCG). However, no biofuel can currently replace anthracite briquettes. Unlike ordinary solid fossil fuels, anthracite briquettes are heated for a long time and retain the same form after combustion, making them easier...
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In developing countries’ socio-environmental background, fossil fuel use is evolving at the same time as deforestation, resulting in desertification and global warming. There is an urgent need to find alternative sustainable and environmentally friendly sources such as biomass briquettes. This study aims to analyse the effect of densification tempe...
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... Coffee (Coffea arabica), a tropical and southern African and tropical Asian shrub is falling under the family Rubiaceae and genus coffee and is most commonly known for yielding caffeine-rich coffee beans, which are predominantly used as numerous edible and non-edible products. On average, one tonne of coffee beans produces about 650 kg of these spend coffee ground wastes and almost 7-9 million tonnes of SCG were produced against 166.63 million 60 kg bags of fresh coffee powder, during the year 2021 (García-García et al., 2015;Girotto et al., 2018;Kim et al., 2022;Santos et al., 2017). Eventually, these wastes are widely celebrated for its high energy content and have received less attention in processing them into fuel source. ...
Briquetting of biomasses is an ideal technique for improvising both its volumetric and net energy density; besides, it serves as an effective means for reducing their pollution. In general, numerous biomass and organic by-products are discarded as wastes, citing their non-edibility, composition of chemical compounds present in their raw form, and zero usage value. Yet, these biomass wastes hold significant heating values, which promote them into promising solid biofuels, either in their existing or pre-treated form. Accordingly, this review article discusses the various biomasses used as raw feedstock for briquetting, besides summarising the works carried out in relevance to their respective briquettes. In addition, the proximate and lignocellulosic composition of these biomasses, and their pre-treatment techniques followed to prepare them for briquetting, have also been discussed. This study suggested that the heating value of biomasses ranged between 10 and 20 MJ/kg, while their briquettes reported between 15 and 25 MJ/kg, thereby citing their potential as viable replacements for existing fossil coals. Besides, factors affecting different thermal and physicochemical properties of these briquettes have also been studied and these properties play a crucial role in deciding the overall quality of the briquettes. Ultimately, this study proposes that any biomass with good calorific value and lignin content can be processed into briquettes with good strength and durability; however, the choice of biomass will also be accounted for by its availability, geographical distribution and handability.
... Under normal conditions, the coffee industry can produce an average of 720 tons of fried coffee in one month, and after the extraction process, the final product is 55% of the overall process; consequently, 396 tons of product and 324 tons of coffee grounds are acquired [7]. Several research [8][9][10] investigated the usefulness of coffee ground as briquette materials. Most studies try to find out not only once agriculture waste could be used to make briquettes, but also what the best mixture ratio is to make briquettes that work well in terms of their physical, chemical, and burning qualities. ...
... SCG are solid residues obtained after the preparation of coffee as a beverage [7]. Approximately 650 kg of SCG is obtained from 1 ton of coffee beans [8]. SCG are a large amount of solid waste released by coffee consumption causing storage and disposal problems [6]. ...
... Biopellet has a calorific value of 5,000 -5,100 cal / g or equivalent to the calorific quality of low-energy coal (Firmanda et al., 2023). In another case, the incineration of coffee grounds waste in pellets reduces Nox emissions due to the synergistic effect on combustion (Kim et al., 2022). However, coffee grounds have cross-sectoral health, agriculture, and alternative energy benefits. ...
The development of the coffee business as a small and medium enterprise (SME) shows positive things with the increasing number of coffee, which means an abundance of existing coffee grounds. There is a lack of research on entrepreneur perspectives on coffee waste management. This study aims to analyze the perspective of coffee shop entrepreneurs in managing coffee waste and converting waste into alternative energy for sustainable and environmentally friendly prospects. Respondents in this study were 201 coffee shop owners in Bekasi, Indonesia, who received questionnaires using the snowball sampling technique; for data analysis, the paper used PLS-SEM. This study found that the entrepreneur perspective significantly affects coffee waste management, encouraging the sustainability of coffee shops. The results of the R-Square analysis show that coffee shop owner awareness is strongly influenced by coffee waste management knowledge (93.6%); the attitude of coffee shop owners is influenced by coffee waste management knowledge and coffee shop owner awareness (92.5%); and the coffee waste management behavior is influenced by coffee shop owner awareness and attitude of coffee shop owners (97.8%). In addition, entrepreneurs’ excellent attitudes and awareness toward the potential of coffee grounds encourage them to carry out better waste management through sorting procedures to convert coffee grounds into alternative energy. AcknowledgmentThis study is funded by the Directorate of Research and Development, Universitas Indonesia, under Hibah PUTI 2022 (Grant No. NKB-1364/UN2.RST/HKP.05.00/2022).
... On the contrary, the low-heat-capacity coal can produce fewer calories and emit more harmful pollutants during combustion. However, it is cheaper than the high-heat-capacity coal [9]. Some coal-fired power plants located in developed countries use only high-heat-capacity coal regardless of its high price [10]. ...
... However, XGBoost and random forest do not provide a large variance of performance depending on the hyperparameters of the model. On the other hand, the prediction accuracy of the DNN model for SO x , training with the following hyperparameters: activation function = Relu; layer = (input layer (number of input variables), hidden layer (9,18,36,18,9,9), and output layer (1); value in () means number of nodes of each layer); drop out = none; weight initialization = He initialization; optimizer = Adam, gives the best result as MAPE = 7.1%. NO x prediction by the trained DNN model with the following hyperparameters: activation function = Relu; layer = (input layer (number of input variables), hidden layer (15,30,60,30,15,5), and output layer (1); value in () means number of nodes of each layer); drop out = none; weight initialization = He initialization; optimizer = Adam, gives the best result, with MAPE = 5.68%. ...
... However, XGBoost and random forest do not provide a large variance of performance depending on the hyperparameters of the model. On the other hand, the prediction accuracy of the DNN model for SO x , training with the following hyperparameters: activation function = Relu; layer = (input layer (number of input variables), hidden layer (9,18,36,18,9,9), and output layer (1); value in () means number of nodes of each layer); drop out = none; weight initialization = He initialization; optimizer = Adam, gives the best result as MAPE = 7.1%. NO x prediction by the trained DNN model with the following hyperparameters: activation function = Relu; layer = (input layer (number of input variables), hidden layer (15,30,60,30,15,5), and output layer (1); value in () means number of nodes of each layer); drop out = none; weight initialization = He initialization; optimizer = Adam, gives the best result, with MAPE = 5.68%. ...
Coal has been used as the most commonly energy source for power plants since it is relatively cheap and readily available. Thanks to these benefits, many countries operate coal-fired power plants. However, the combustion of coal in the coal-fired power plant emits pollutants such as sulfur oxides (SOx) and nitrogen oxides (NOx) which are suspected to cause damage to the environment and also be harmful to humans. For this reason, most countries have been strengthening regulations on coal-consuming industries. Therefore, the coal-fired power plant should also follow these regulations. This study focuses on the prediction of harmful emissions when the coal is mixed with high-quality and low-quality coals during combustion in the coal-fired power plant. The emission of SOx and NOx is affected by the mixture ratio between high-quality and low-quality coals so it is very important to decide on the mixture ratio of coals. To decide the coal mixture, it is a prerequisite to predict the amount of SOx and NOx emission during combustion. To do this, this paper develops a deep neural network (DNN) model which can predict SOx and NOx emissions associated with coal properties when coals are mixed. The field data from a coal-fired power plant is used to train the model and it gives mean absolute percentage error (MAPE) of 7.1% and 5.68% for SOx and NOx prediction, respectively.
... Moreover, firewood has higher volatile matter contents than charcoal and therefore ignites faster to allow core complete combustion than charcoal [26,34]. A study by Kim et al. (2021) attributed lower CO emissions to low carbon contents [35]. From an earlier study, the fixed carbon compositions of firewood (12.07-20.34%) ...
Firewood and charcoal are the most dominant sources of fuel for domestic cooking applications in sub-Saharan Africa. In this study, performance and emission characteristics of firewood and charcoal from five commonly used species, namely, Dichrostachys cinerea, Morus Lactea, Piliostigma thonningii, Combretum molle, and Albizia grandibracteata were obtained. The water boiling test and emissions monitoring system for CO, CO 2 , and PM 2.5 were used to determine fuel and energy consumption, thermal efficiency and emissions, and emissions' factors. The results showed that firewood combustion required higher energy consumption compared to charcoal combustion. High-power thermal efficiency was the highest (> 45%) for all charcoal derived from the firewood species. During hot-start, cold-start, and simmering operations, it was observed that thermal efficiencies were generally higher for charcoal fuels (≥ 80%) compared to the firewood (< 40%) from where they were pyrolyzed. Firewood has a much lower indoor CO emissions footprint when compared to using charcoal. Nonetheless , CO emission levels for both firewood and charcoal exceed the Environmental Protection Agency (EPA) guidelines of 35 ppm (1-h average). CO 2 emission factors are the most dominant and highest contributors to greenhouse gas emissions from household use of firewood and charcoal. Overall, this work reaffirms the need for proper ventilation when firewood and charcoal are used in combustion.
... Kim described that SCG in briquettes mixed with anthracite reduces durability [35]. The sample with 20% SCG by weight lasted about 580 min, compared to 70%, lasting only 300 min [34]Balsecatested masses of0.25, 0.50, and 0.75 kg SCG briquettes to evaluate the relationship between temperature and time their combustion produces flame or embers. Flame production required between 5 and 14 minutes, whereas embers lasted between 100 to 175 minutes. ...
... In addition, SO 2 emissions enlarged with rising SCG content [31]. In similar research, Kim found that SCG addition reduced CO and CO 2 , but if the SCG exceeds 20%, NO 2 and SO 2 emissions increase [34].Kangconducted a test on a small firetube boiler and discovered that CO and NOx emissions were 643and 163 ppm, respectively. The O 2 concentration increased through a fan installed in the chimney. ...
Several studies have been developed worldwide to find alternative fuels that can contribute to minimizing global warming impacts. In addition, most of the population in rural areas in developing countries uses firewood as the only source of energy due to the lack of gas, electricity, or distilled fuels. The exposition to smoke released during the combustion process causes serious lung diseases such as asthma, emphysema, and chronic obstructive pulmonary disease (COPD). This project addresses the physicochemical and mechanical behavior of briquettes made of spent coffee grounds (SCG) blended with recycled newsprint (NP) to compare their performance against firewood, coal, and other briquettes from different biomasses. Batches of briquettes SCG: NP in proportions 50:50, 70:30, and 80:20 weight were elaborated to evaluate the properties. The results were analyzed under NTC 2060 and EN 15210 standards and compared to similar studies globally. Although many parameters did not reach established values, this solid fuel is a potential alternative to replace firewood and coal, especially in places with no other energy source.
... Coffee is an important industrial sector in about 80 countries, and one of the most popular beverages and the second largest traded commodity after petroleum [11][12][13][14][15][16]. Global coffee consumption has been increasing annually, with more than 9.9 billion kilograms consumed in 2021 [17]. The spent coffee grounds (SCG) consist of the grinds remaining after the extraction of desirable compounds with hot water to produce a coffee beverage or during the production of instant coffee preparations [18,19]. ...
... Nosek, et al. [21] studied the use of SCG as fuel in pure and blends with sawdust using a fixed bed boiler (18 kW). Kim et al. [17] investigated the combustion of SCG briquettes in terms of emissions and shape retention compared to anthracite briquettes. Colantoni et al. [16] studied the combustion of pellets made of pure SCG and SCG blended with sawdust using a fixed bed boiler (80 kW). ...
The co-combustion of coal and waste biomass is an advantageous option for combined waste biomass disposal and energy production. However, co-firing coal with waste biomass has to overcome various ash-related operational problems, for example, ash agglomeration and bed defluidisation in fluidised bed boilers. Using spent coffee grounds (SCG) for energy generation via co-combustion is much more sustainable and environmentally friendly than SCG disposal in landfills. The research done so far on the co-combustion of coal and SCG is quite scarce and almost non-existing. Further research is needed to understand how the properties of SCG affect the co-combustion of coal and SCG in existing coal-fired boilers. This study investigates the combustion of a bituminous coal blended with SCG in a pilot-scale (30kWth) bubbling fluidised bed (BFB) combustor focusing on CO and NOx emissions, combustion performance, and agglomeration tendency. The BFB combustion tests were conducted at 900 °C and atmospheric pressure using silica sand as the bed material. For comparison purposes, combustion tests of the same coal in pure and blended with wheat straw pellets at the same blending ratio were also performed. Further, ash fusibility studies were performed to elucidate the interactions between the coal ash and SCG ash, and the effect of ash compositions on the fusibility temperatures. Samples of the used bed material collected from the combustor and cyclone ash were characterised by SEM-EDS and XRF. The BFB combustion test results revealed that SCG could reduce the efficiency loss of coal combustion under co-combustion conditions. Despite the higher K2O content in SCG compared to wheat straw, a reduced agglomeration tendency was observed with the BFB combustion of the coal-SCG blends. The results from the characterisation of the used bed material, cyclone ash, and ash fusibility studies confirmed this finding, which was attributed to the formation of high melting temperatures Mg- and Ca-bearing compounds.
... The amount of CO and CO2 released during combustion is influenced by a range of factors. For instance, Kim et al. (2021) in their attempt to compare emission from different briquettes attributed the lower CO and CO2 emission from combustion of briquettes densified from spent coffee grounds to their less carbon content (46.1-54.9 wt. ...
Over reliance on charcoal has accelerated deforestation in sub-Saharan Africa. Seeking alternative sustainable and environmentally friendly sources of biomass energy to meet the escalating energy demand is therefore vital. However, limited evidence exists on the concentrations of toxic emissions of different biomass fuels. Herein, dried human faeces and sawdust were pyrolyzed at 350 °C to produce biochar and mixed in equal ratio to produce briquettes through densification, with molasses (10 wt.%) used as a binder. A comparative study on the heating properties and emission level of carbon monoxide (CO), nitric oxide (NO), and hydrogen sulphide (H2S) during combustion of charcoal, and co-combustion (50:50 wt. %) of charcoal with briquettes was conducted. The thermal profile of the flue gases indicated rapid combustion of volatile gases followed by slow oxidation of the char. Co-combustion significantly (P < 0.05) enhanced the amount of heat energy released with flue gases temperatures reaching a peak of 475 °C. The briquettes had a gross calorific value of 19.8 MJ/kg which was lower than 25.7 MJ/kg for charcoal. Combustion of charcoal did not emit NO, however the concentration of CO was above the critical short term limits of 35 ppm. The concentration of CO and H2S was above the short term exposure limits of 35 ppm, and 0.005 ppm, respectively, during co-combustion, whereas NO concentration was below dangerous exposure levels of 100 ppm. These results suggest that co-combustion of charcoal with the briquettes is a promising approach to generate safe and sufficient heat energy for cooking and reduce deforestation.
... Though, they occur in wide varieties, only certain species are accounted for producing these caffeine rich beans; hence, stating them as most valuable commodity crops. on average, one tone of coffee beans produces about 650Kg of these spend coffee ground wastes; and almost 7-9 million tons of SCG were produced against 166.63 million 60 kg bags of fresh coffee powder, during year 2021 (Santos et al., 2017;Girotto et al., 2018;García-García et al., 2015;Kim et al., 2022). Eventually, these wastes are widely celebrated for its high energy content, and have received less attention in processing them into fuel source. ...
Briquetting of biomass is an ideal technique for improvising both its volumetric and net energy density; besides, serving as an effective means for reducing pollution. In general, numerous biomass and organic by-products are discarded as wastes, citing their non-edibility, composition of chemical compounds present in their raw form, in addition to their zero usage value. Yet, these biomass wastes hold significant heating values, which promote them into promising solid biofuels, either in their existing or pre-treated form. Accordingly, this review article discusses about the various biomasses used as raw feedstock for briquetting, besides summarising the works carried out in relevance to their respective briquettes. In addition, proximate and lignocellulosic composition of these biomasses, and their pre-treatment techniques followed to prepare them for briquetting, have also been discussed. This study suggested that the heating value of biomasses ranged between 10- 20 MJ/kg, whilst, their briquettes reported between 15 and 25 MJ/kg; thereby citing their potential as a viable replacement for existing fossil coals. Besides, factors affecting different thermal and physicochemical properties of these briquettes have also been studied and concluded that these properties play a crucial role in deciding the overall quality of the briquettes. Ultimately, this study proposed that any biomass with good calorific value and lignin content can be processed into briquettes with good strength and durability; however, the choice of biomass will also be accounted for by its availability, geographical distribution, and handleability.
