The electricity deficit in Cameroon is estimated today at 50 GWh. This deficit characterized by frequent and sometimes prolonged load shedding, disrupts economic and social life. To overcome this ...electricity deficit, Cameroon took the decision to produce 3000 MW of electrical energy from its renewable energies potential. Indeed, the annual solar radiation in Cameroon varies from 4.28 kWh/m2/year to 5.80 kWh/m2/year. It has 25 million hectares of forest covering three-quarters of its territory, amounting to the third-largest biomass potential in sub-Saharan Africa. In addition, there is an intense breeding activity for cattle, goats, sheeps and pigs in the Far North region amounting to several million heads and generating large quantities of dung. This paper therefore investigates for the very first time the techno-economic feasibility by using HOMER Pro of two scenarios of hybrid systems namely, PV/Fuel Cell/Electrolyzer/Biogas (scenario 1), and PV/Battery/Fuel Cell/Electrolyzer/Biogas (scenario 2) for energy and Hydrogen production in the city of Maroua, recognized as being part of the sunniest region (Far North) of Cameroon. The combination of electrolyzer, fuel cell and hydrogen tank was used in the present design to reduce battery storage requirement. Three types of household electricity demands communities (low, medium and high consumers) were considered in this work. The results showed that the optimal system architecture for scenario 1 included 144 kW PV module, 15 kW biogas generator, 11 kW converter, 15 kW electrolyzer, 15 kW fuel cell and 5000 kg Hydrogen tank with a dispatch strategy of cycle charging (CC) for low consumers community. For medium consumers community of scenario 1, 879 kW PV module, 15 kW biogas genetrator, 31.9 kW converter, 24 kW fuel cell, 24 kW electrolyzer and 5000 kg Hydrogen tank with a CC dispatch strategy was the best hybrid system. For high consumers community of scenario 1, 11,925 kW PV module, 15 kW biogas generator, 570 kW converter, 266 kW fuel cell, 266 kW electrolyzer and 25,000 kg Hydrogen tank with a CC dispatch strategy was the best hybrid system. Concerning scenario 2, the following architectures were the best hybrid systems: for low consumers, 138 kW PV modules, 15 kW biogas generator, 27.2 kW converter, 15 kW fuel cell, 15 kW electrolyzer, 5000 kg Hydrogen tank and 480 batteries storage bank with a CC dispatch strategy; for medium consumers, 234 kW PV modules, 15 kW biogas generator, 57.8 kW converter, 24 kW fuel cell, 24 kW electrolyzer, 5000 kg Hydrogen tank and 1023 batteries storage bank with a load following (LF) dispatch strategy; and for high consumers, 820 kW PV modules, 15 kW biogas generator, 405 kW converter, 266 kW fuel cell, 266 kW electrolyzer, 25,000 kg Hydrogen tank and 9519 batteries storage bank with a CC dispatch strategy. The levelized costs of energy (LCOE) for scenario 1 were US$ 0.871/kWh, US$ 0.898/kWh and US$ 1.524/kWh for low, medium and high consumers communities respectively. Concerning scenario 2, the LCOE were US$ 0.139/kWh, US$ 0.091/kWh and US$ 0.071/kWh. In addition, it was found a levelized costs of Hydrogen (LCOH) for scenario 1 of US$ 7.66/kg, US$ 4.95/kg, and US$ 0.45/kg for low, medium and high consumers communities respectively. For scenario 2, the LCOH were US$ 3.06/kg, US$ 1.34/kg and US$ 0.15/kg for low, medium and high consumers communities respectively. It was also concluded from the optimization results that the combination of water electrolyzer, fuel cell and hydrogen tank coupled to biogas generator and PV modules could be used as an alternative solution to make electricity available and accessible to the population of the Far North region of Cameroon.
•PV/Battery/FC/Electrolyzer/Biogas and PV/FC/Electrolyzer/Biogas systems are studied.•Electrolyzer, FC and Hydrogen tank combination reduced battery storage requirement.•Low, medium and high consumers electricity demand communities were considered.•The overall levelized cost of energy varied from US$ 0.071/kWh to US$ 1.524/kWh.•The overall levelized cost of Hydrogen varied from US$ 0.45/kg to US$ 7.66/kg.
The constant growth of livestock husbandry in China in recent years has raised grave concerns about severe environmental pollution. A countrywide, comprehensive assessment of the quantity and ...distribution of livestock excrement (LE) production could significantly promote contamination control methods and biogas development in China. Previous researchers have reported an excessively wide range of LE quantities and have failed to reach a consensus conclusion. By using the latest updated LE definitions and calculation coefficients, LE and its biogas potential were assessed for 14 types of livestock in this study according to China’s husbandry statistics data. LE increased by 10.9% from 1563.2 Mt in 2007 to 1755.0 Mt in 2015 at a rate of 12.3% in fresh weight and increased by 12.8% from 367.1 Mt to 414.5 Mt in dry weight. The mean annual LE from 2013 to 2015 was estimated on a dry weight basis as 414.9 Mt. Most of the LE produced from 2013 to 2015 was by cattle (including draft cattle, beef cattle, and dairy cows), followed by sheep (including goats), poultry (including broiler chickens, egg chickens, ducks, and geese), pigs, and other livestock (including horses, donkeys, mules, camels, and rabbits). Among the six regions, from 2013 to 2015, the LE was distributed in ascending order in the Northwest, Northeast, Southwest, North, Central-south, and East regions on a dry weight basis. The average LE produced among the 31 provinces in China ranged widely from just 0.8 Mt (Shanghai) up to 42.4 Mt (Shandong), with the latter having the highest LE density distribution (275.7 t km-2) on a dry weight basis. The east-middle provinces, Liaoning, Shandong, Henan, Hebei, Tianjin, Jiangsu, and Anhui, exhibited relatively higher levels of LE density distribution (111.2–275.7 t km-2) than those of other regions. The yearly total LE generated from commercial scale husbandry feedlots (CSHF) for 2015 was estimated at 141.5 Mt, which amounts to a biogas potential of 60.6 billion m3 (Billion refers 1 × 109). Scenario analysis predicts that by 2030, the annual LE from CSHF could range from 201.1 to 258.9 Mt, corresponding to biogas potential of 86–111 billion m3. The results of this countrywide study suggest that there are significant opportunities to improve LE management and to achieve ecological livestock husbandry in China.
•Livestock excrement rose by 12.8% from 367 to 414 Mt (dry) in 2007–2015 in China.•In 2013–2015, 36% of it was from cattle and 18–19% from sheep, pigs, and poultry.•The 7 provinces in east-middle area showed highest excrement density distribution.•The biogas potential of excrement from commercial feedlots was 6.1 × 1010 m3 in 2015.•Biogas from it could range from 8.6 × 1010 to 1.1 × 1011 m3 under 4 scenarios by 2030.
•Composting increased DOM molecular weight and humification degree.•FRI and AFE were used to assess the changes in DOM components during the composting.•2D-FTIR-COS can identify the sequential order ...of structural change in compost DOM.
Dissolved organic matter (DOM) extracted from composting of biogas residue was characterized using spectroscopic techniques. Spectral parameters, specific UV absorbance at 254 (SUVA254), ratios of spectral slopes (SR), and humification index (HIX) were used to assess the structural characteristics of the DOM. During composting, the UV absorbance at 254 increased as the relatively resistant aromatic fraction was released and the DOM molecular weight increased with the degree of humification. Fluorescence excitation-emission matrix (EEM) spectra with regional integration analysis (FRI) and accumulative fluorescence emission (AFE) combined with second derivative spectroscopy were used to assess the evolution of the DOM and evaluate the production of resistant humic-like substances during composting. Second derivative spectroscopy showed that microbial-derived humic-like substance A2 was easily degraded during composting. Two-dimensional correlation spectroscopy (2D-COS) combined with Fourier-transform infrared (FTIR) spectroscopy determined the preferential change sequence of the functional groups was 2000–2300 (CC or CN) → 1288 cm−1 (amide III) at x1 and 2935 (aliphatic groups) → 1420 (carboxylic groups) → 3100–3400 (hydroxyl groups) → 1660 cm−1 (aromatic CC) at x2, suggesting that functional groups of CC or CN, and amide III can be degraded preferentially, and aromatic CC groups were difficultly degraded. The present study showed spectroscopic techniques are valuable tools for assessing composting of biogas residues.
Anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW) offers the possibility of a clean and renewable energy source – i.e. biogas. However, OFMSW lacks certain ...characteristics that may limit its efficacy as such a resource. Bio-resources such as sewage sludge and animal wastes have these characteristics and so may be used to enhance OFMSW's digestion. Anaerobic co-digestion (AcoD) of OFMSW with sewage sludge has been extensively studied and applied successfully at full-scale. Pre-treatments can increase substrate biodegradability and so biogas yield, but these may need further investigation to determine economic viability. Mathematical modeling has been shown useful in aiding selection of appropriate combinations of substrates and pretreatment for co-digestion (e.g. substrate type and mix ratio). This review also considers the fate of the digestate following such anaerobic co-digestion. The difficulties in implementation of the co-digestion approach need not necessarily be technical in nature but can be due to management issues.
•Up to date information on AcoD of the organic fraction in municipal solid waste.•Review of the impact of operational parameters on AcoD performance.•Information on full-scale experiences.•Consideration of economic and environmental feasibility.•Key challenges and research needs in the development of AcoD.
•Mechanical pretreatments were applied to different lignocellulosic biomass.•The structural components of all biomass were deconstructed by the pretreatment.•There was enhancement in methane yield up ...to 22% over the untreated biomass.•Correlation was established between chemical composition and biodegradability.
In this study, mechanical pretreatment was applied to six different lignocelluloses in two different treatment phases and the prediction of their methane yield was done from biomass chemical composition. Physicochemical, proximate and microbial analyses were carried out on both pretreated and untreated biomass using standard methods. Mechanical pretreatments caused the breakdown of structural materials in all the used biomass which was characterized by reduction of the lagging time during anaerobic digestion and the subsequent increase in methane yield up to 22%. The different loading rate of biomass had no effect on the overall methane yield increase. Both single and multiple linear regressions models were used in order to correlate the chemical composition of the biomass with their methane potentials and a fairly high correlation (R2 = 0.63) was obtained. The study also showed that the pretreatments are economically feasible. Therefore, its further application to other biomass is encouraged.
RESUMO Estações de tratamento de esgoto (ETE) com processos anaeróbios estão consolidadas na América Latina. Suas diversas características favoráveis tornam-nas uma opção atrativa para regiões de ...clima quente, mas existem ainda restrições, como as relacionadas às emissões gasosas difusas. Nesse contexto, o presente trabalho objetivou o desenvolvimento da ferramenta computacional Balanço de Energia e Carbono em ETE Anaeróbias (BECarbon0), com base na compilação, em planilha eletrônica, de equações e coeficientes da literatura especializada, que permite comparar diferentes cenários e alternativas tecnológicas para o manejo de emissões gasosas em ETE que empregam reatores anaeróbios de fluxo ascendente e manta de lodo (UASB). Possibilita-se assim que projetistas e tomadores de decisão avaliem aspectos de recuperação de energia e gestão da pegada de carbono. Por fim, apresenta-se um estudo de caso fictício com três cenários cujos resultados apontam para a possibilidade de redução da pegada de carbono total da ETE em 82% se comparada à configuração normalmente adotada no Brasil.
ABSTRACT Sewage treatment plants (STPs) with anaerobic processes are consolidated in Latin America. Their several favorable characteristics make them an attractive option for regions with a hot climate, but there are still restrictions, such as those related to diffuse gaseous emissions. In this context, the present work aimed at developing the computational tool Energy and Carbon Balance in Anaerobic STPs (BECarbon0), based on the compilation, in a spreadsheet, of equations and coefficients from the specialized literature, which allows comparing different scenarios and technological alternatives for the management of gaseous emissions in STPs based on upflow anaerobic sludge blanket reactors (UASB). This should enable designers and decision makers to assess aspects of energy recovery and carbon footprint management. Finally, a fictitious case study is presented with three scenarios whose results point to the possibility of reducing the total carbon footprint of the STP by 82% compared to the configuration normally adopted in Brazil.
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•Challenges and complexities in AD process of LWs were reviewed.•Effective strategies to improve the performance of AD process were evaluated.•Various physical, chemical and ...biological methods were discussed.•Biological treatment, particularly bioaugmentation can be advantageous for LWs.•Mechanisms and microbial interactions with LWs are yet to be explored.
Along with the growing energy demand and the rising concerns over the environmental impacts of fossil fuels, much attention has been recently drawn toward the possibility of exploiting organic or biodegradable wastes, including lignocellulosic wastes (LWs), as the sources of renewable energy. Notably, the anaerobic digestion (AD) of such wastes can mitigate environmental damage, and then produce biogas and bioenergy for low-income rural communities, which is particularly worthwhile in developing countries. Nevertheless, progress in this field has been hindered by a multitude of challenges, e.g., the floating of such wastes on the top of reactors, which typically obstructs gas flow, high carbon-to-nitrogen ratio (CNR), and brings about an almost complex structure of LWs as well as their poor degradability because of high lignin content. In spite of that, many problems can be tackled by adopting appropriate methods, including providing mixing in reactors, reducing CNR, balancing inoculum-to-substrate ratio (ISR), and performing chemical and biological pretreatments. Against this background, the present study aimed to review the related literature on the AD of LWs to identify the existing challenges, and reflect on the strategies to deal with them for the purpose of improving bioenergy production from this type of waste.
As a result of air pollution and accelerated climate change, entrepreneurship is gradually becoming a deciding factor in the global conversation about saving the planet with renewable energy sources. ...To sustain the economy and entrepreneurial culture for future generations, researchers and entrepreneurs seek environmentally friendly methods for supporting entrepreneurial enterprises. Fossil fuel–based energy has significantly impeded the country’s sustainable development. Pakistan lacks research examining the connection between biogas energy technology and entrepreneurship. This study aims to cover this void in the literature by employing the theory of planned behavior to investigate bioenergy as a business prospect for supportable monetary growth. The primary data comprises 358 comprehensive questionnaire survey respondents. PLS-SEM verifies the model and examines the suppositions. According to pragmatic findings, all views are positively and substantially associated with the sustainable progress of business enterprises implementing biogas energy. In contrast, social media awareness had no moderating effect on the dependent variable. Consequently, social media awareness substantially modifies the associations between all independent variables adopting biogas energy. The results of this research indicate the standing of altering social customs regarding private enterprise, increasing businesspersons’ consciousness of these matters, reforming controlling arrangements, and highlighting the assistance of business events made possible by biogas energy technology, which increases businesspeople’s investment returns. Conclusively, the study’s limits and approvals for future research are emphasized.
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•Biochar provided microbial habitat in AD system and enhanced biogas production.•Excellent buffer capacity and accelerated electron transferring was observed.•Biochar applications for ...biogas generation and purification were analyzed.•Economic and environmental feasibilities of biochar addition in AD were evaluated.
Anaerobic digestion (AD) technology still faces some challenges including low methane productivity, instable operation efficiency and undesired refractory substances degradation. Biochar has recently been recognized as a promising alternative addition in AD process to enhance methane production. Based on VOSviewer analysis, this review presents a comprehensive summarizing of the applications, performances, and economies of biochar strategies in AD system. Firstly, typical production processes of biochar and its main characteristics including adsorption and immobilization ability, buffering ability and electron transfer ability were evaluated. Then, the applications of biochar in AD and its improving effects on biogas production/purification were summarized. Accordingly, the corresponding mechanisms of biochar addition in AD for digestion efficiency improvement were elucidated. Finally, the economic and environmental feasibilities of application biochar in AD, as well as prospective future studies were summarized. Through an overview of biochar in AD system, this paper aims to promote its widely practical applications.
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