Biogas Utilization Research Articles

Optimising Biogas Utilisation from Palm Oil Mill Effluent in Dual-Fuel Engines: A CFD Simulation Approach

The transition towards sustainable energy is crucial for mitigating climate change and reducing dependence on limited fossil fuels. This study aims to optimise the utilisation of biogas generated from palm oil mill effluent (POME) in dual fuel engines through computational fluid dynamics (CFD) simulation. However, this study addressed the challenge of variation in the composition of raw biogas. These differences may make it difficult to effectively control the combustion of internal combustion engines. Thus, to overcome this challenge, the composition of biogas is fixed throughout the cleaning and reforming stages in this study. Using a three-dimensional computational model to evaluate the operation of a single-cylinder compression ignition engine at 1300 rpm under traditional diesel and dual fuel conditions. Due to the symmetry of the cylinder and the periodic pattern of the injector nozzle holes, a 60-degree sector grid representing one-sixth of the cylinder was selected to simulate the entire geometric shape. Using ANSYS Forte software for CFD combustion simulation, this study investigates the effects of reforming biogas substitution on the indicated average effective pressure, total power, thermal efficiency, combustion efficiency and emission characteristics of nine different biogas diesel components (from 0% to 0%). 80% biogas substitution is 20% step size. The research results indicate that replacing diesel with gas fuels such as reformed biogas in dual-fuel engines can affect the performance and efficiency of the engine. Although combustion efficiency and thermal efficiency may initially increase, they will significantly decrease at higher substitution rates, especially at 80%. Nevertheless, reforming biogas still has advantages such as reducing emissions and maintaining output power at medium to high loads. However, compared to traditional diesel engines, challenges such as decreased volumetric efficiency and indicated mean effective pressure (IMEP) lead to an overall decline in engine performance.

Masjid Az-Zikra Sentul: Transformasi dari Eco-Masjid ke Eco-Sosial

Mosques are not only places of worship, but also serve as centers of education and social change. Given the increasing environmental challenges, mosques have an important role in raising ecological awareness. This study examines the implementation of eco-friendly principles at Az-Zikra Mosque in Sentul, Bogor, during the period of Khotib Kholil Foundation Chairman (2016-2022), as well as its role in educating the community about environmental conservation. Through qualitative research involving interviews, observations, and documentation, this study explores various environmentally friendly initiatives at the mosque, which include maximizing water usage, bioclimatic architectural design of mosque buildings, utilization of biogas, waste management with incineration technology, urban green space management, and plastic bottle waste alms movement. Research informants include mosque administrators, worshipers, volunteers, and the surrounding community. Using Elinor Ostrom's Theory of Co-management of Natural Resources (Commons Management), this study proves that Az-Zikra Mosque not only successfully implements ecological practices efficiently with evidence of successfully applying the concept of eco-mosque according to Green Building Council Indonesia (GBCI) standards, but is also able to make ecological activities at the mosque an effective medium of ecological education to the local community by involving them directly in environmentally conscious activities. The research findings show that mosques are able to apply a holistic approach to sustainability by optimizing natural resources, providing ecological education, and integrating environmental awareness with spiritual values. Research recommendations include increasing collaboration between mosques and communities, strengthening partnerships with government and the private sector, encouraging other mosques to adopt environmentally friendly practices, developing religious education modules that integrate ecological awareness, and creating an evaluation system to measure the impact of mosque environmental initiatives on an ongoing basis.

Experimental Assessment of Energy-Ecological Parameters of Biogas-Powered Tractor Within Circular Economy

One of the solutions contributing to the development of energy independence is the utilization of biogas as an alternative fuel for agricultural tractors. Biogas is recognized as a renewable energy source, and its usage aids in the reduction in greenhouse gas emissions on a global scale. The reuse of this material/waste exemplifies the concept of a circular economy. Several models of agricultural tractors designed explicitly for biogas utilization or adaptable for its use are available in the market. This study aimed to evaluate the energy-ecological parameters of the MP tractor (T6.180 Methane Power) powered by Compressed Natural Gas (CNG) in comparison to its structurally identical counterpart fueled by Diesel (T6.180 Electro Command). Based on the Air–Fuel Ratio (AFR) coefficients for diesel and methane, as well as values of air excess ratios (λ) and the proportions of CO and CO2 emissions determined for various engine load states, the mass emission of selected exhaust components for the examined tractors was estimated. This research highlights that biogas-powered tractors hold the potential to contribute to the sustainable development of agriculture through the reduction in greenhouse gas emissions, improvement in farm energy autonomy, and optimal resource utilization, closely aligned with the principles of a circular economy.

Strategi Pemberdayaan Petenak melalui Program Pemanfaatan Biogas dalam Mewujudkan Desa Mandiri Energi di Kecamatan Musuk Kabupaten Boyolali

ABSTRACT The research aims to identify strategies for empowering farmers through biogas utilization programs in realizing Energy Independent Villages. This research was carried out in Sruni Village, Musuk District, Boyolali Regency, in March-April 2024. The method is a survey, the data collection technique in this study uses the Participatory Rural Appraisal (PRA) technique. Data from this study was collected through observation, interviews, and Focus Group Discussions (FGD). The sampling of this study was determined by a census of 45 people. The research data obtained was analyzed using SWOT analysis. The strength factors in this development program are the economic value of biogas is higher than other fuels, the value of biogas benefits is higher, the role of biogas in the value of environmental pollution The role of the government in the development of biogas. The weak factors in this business are the installation of biogas pipes that are easily clogged, and the maintenance of livestock is part-time. The opportunity factor of this program is to become a place of education and encourage the progress of the livestock sector. Threat factors such as perishable biogas installations and high gas pressure temperatures can cause explosions. The empowerment strategy of livestock farmer groups in Sruni Village, Musuk District, Boyolali Regency includes efforts to develop the creative economy, efforts to improve the quality of biogas, efforts to develop biogas installation technology, efforts to strengthen farmer members with groups, efforts to improve livestock business management, efforts to rehabilitate biogas as alternative energy. Keywords: biogas, energy independent villages, focus group discussion (FGD), participatory rural appraisal (PRA), empowerment strategy.

Comparative Economic Analysis of the Utilization of Biogas from Sugarcane Vinasse in Electricity Generation, Transport Fuel and Natural Gas Substitution: A Brazilian case Study

Comparative Economic Analysis of the Utilization of Biogas from Sugarcane Vinasse in Electricity Generation, Transport Fuel and Natural Gas Substitution: A Brazilian case Study

Membrane photobioreactor for biogas capture and conversion - Enhanced microbial interaction in biofilm.

The urgency to mitigate greenhouse gas emissions has driven interest in sustainable biogas utilization. This study investigates a 1 L enclosed membrane photobioreactor (MPBR) using a microalgae-methanotroph coculture for biogas capture. Operating with a hydraulic and solid retention time of 7days and a biogas loading rate of 2.7 L /day, the introduction of gas membrane module increased CO2-C and CH4-C uptake rates by 12% and 50%, respectively. Biofilm formation on the membrane surface enhanced system performance, with imaging analyses revealing methanotroph predominantly located near the membrane surface and photosynthetic microorganisms distributed throughout. Metagenomic analysis showed shifts in key metabolic pathways, including increased abundance of soluble methane monooxygenase genes and enhanced vitamin B synthesis in the biofilm. These findings highlight the spatial organization and metabolic interactions in methanotroph-microalgae coculture system, providing insights into the role of membrane-induced biofilms in improving MPBR performance for sustainable biogas utilization.

Hygienic aspects of ensuring chemical safety of using new health-saving technologies for the utilization of biogas at solid municipal waste landfills

Introduction. Environmental health issues are currently among the most important for the population of large administrative and industrial centers. Improving the quality of the environment and creating comfortable living conditions for humans using environmentally friendly methods is one of the current topical areas in environmental hygiene. Materials and methods. The assessment of the effectiveness and chemical safety of the application of a new technology for the collection, purification, neutralization, and disposal of landfill gas for the content of a wide range of organic compounds C5–C20 at a municipal solid waste landfill was carried out using a chromato-mass spectrometric method that allows identifying and quantifying with sensitivity at and below hygienic standards a wide range of organic compounds C5–C20 in air with an unknown composition of pollutants. Results. As a result of the operation of the new landfill gas purification system at the solid waste landfill, the total concentration of pollutants, including marginal and aromatic hydrocarbons, oxygen-containing compounds (alcohols, carboxylic acids), organic sulfur-containing compounds, and sulfur dioxide decreased. As a result of the operation of the new landfill gas purification technology, 100% purification from odourous dialkyl sulfides and nitrogen-containing compounds has been achieved. However, at the outlet of the system, compounds not detected at the inlet were identified, which can be considered as products of combustion and transformation of hydrocarbons that are part of landfill gas, the presence of which indicates to the use of an oxidative process in the process of its disposal. Limitations. The study is limited to the application of the method of investigation of organic compounds with the molecular formula C5–C20. Conclusion. For an adequate assessment of the quality and chemical safety to human health of health-saving technologies, an important condition is the use of physical-chemical studies that identify and quantify dozens of pollutants simultaneously, which makes it possible to take into account the multiple componentness of the chemical composition and the possibility of adverse side effects in the form of toxic transformation of products affecting humans in real environmental pollution conditions.

Metabolic coupling of aerobic methane oxidation and short-cut nitrification and denitrification for anaerobic effluent treatment in photo-sequencing batch biofilm reactor

This study explored the use of algae to supply oxygen in situ as an alternative to mechanical aeration for anaerobic effluent treatment in a photo-sequencing batch biofilm reactor (PSBBR). By establishing alternating aerobic (dissolved oxygen (DO) > 2 mg /L)/anoxic conditions (<0.5 mg-DO/L) through a 6-h off/6-h on biogas sparging cycle and continuous illumination (1500–3000 lux), the PSBBR achieved a significant ammonia removal rate of 15–25 mg N L−1d−1. This system demonstrated robust partial nitrification and nitrite reduction activities, coupled with aerobic methane oxidation. Metagenomic analysis revealed the enrichment of key microbial groups, including Leptolyngbyaceae, Methylocystis, Nitrosomonas and Hyphomicrobium. The key functional genes of methane (mmo, mdh, gfa, frm and fdh) and nitrogen (amo, hao, narGHI, and napAB) metabolisms were identified, while notably lacking nitrite oxidation genes. In conclusion, this study provides a promising post-treatment approach for anaerobic effluent through integrating biogas utilization with efficient nitrogen removal.

Comprehensive assessment of sludge wet air oxidation and its combination with anaerobic digestion

Wet air oxidation (WAO) is a promising sludge treatment technology but has yet to be used widely. This study evaluates a new integrated pathway of AD plus WAO, juxtaposing against the standalone AD and WAO, from the aspects of carbon emissions, energy efficiency, and cost-benefits. The assessment unit is 1 t dewatered sludge with a water content of 80 %, and the greenhouse gases are converted to equivalent CO2. WAO can recover the thermal heat released from organic oxidation, resulting in the lowest carbon emissions, 10.92 to −36.86 kg CO2-eq/t. AD plus WAO also performs well with 32.21 to −48.16 kg CO2-eq/t. All three ways can produce renewable energy through biogas utilization or thermal recovery. WAO has the highest energy efficiency of 35%–42 % due to efficient thermal energy recovery, and AD plus WAO has a second-ranked efficiency of 15%–30 %. However, WAO needs expensive facilities and external electricity, resulting in a higher expenditure than AD. The integrated systems also require a high investment, but can simplify digested sludge treatment. According to the normalized scores in the three aspects, WAO is recommended chiefly, especially for treating low-organic-content sludge. AD plus WAO ranked second and can be used for high-organic-content sludge.

Sustainability Assessment of Agricultural Waste Biogas Production System in China Based on Emergy and Carbon Evaluation Methods

Biogas production is widely recognized as an effective solution for addressing agricultural waste treatment in rural areas. However, its development is often hindered by economic and environmental constraints. This study combined emergy evaluation and carbon footprint analysis methods to establish a new environmental radius assessment model for evaluating the ecological performance and optimization direction of an agricultural waste biogas production system, using a biogas production company in China as a case study. Compared with the straw return model and straw power generation model, the results of emergy indicators and carbon accounting showed that the biogas production model had a lower environmental load and higher economic output and level of emergy sustainability. Additionally, the biogas production system was found to reduce 0.47 kg of carbon emissions per 1 kg of agricultural waste utilized. The application of the biogas production model in rural areas had high ecological sustainability and carbon emission reduction benefits. Environmental radius assessment results confirmed that the reasonable changes in resource collection distance could further enhance the ecological sustainability, carbon mitigation ability, and economic benefits of the biogas production system. The environmental radius assessment method offers a new approach to the location planning of agricultural waste biogas utilization companies in rural areas.

INTEGRATED TECHNOLOGY OF BIOGAS UTILIZATION OF SOLID HOUSEHOLD WASTE LANDFILLS WITH THE PRODUCTION OF ELECTROCITY, HEAT AND CARBON DIOXIDE

The presence of carbon dioxyl as a non-combustible admixture in the landfill biogas of solid household waste and the absorption of ambient air into the layer of landfill waste, and therefore its entry into the landfill gas, significantly reduces the concentration of methane in it, which affects the efficient operation of the gas piston engine of the power plant and the reduction of volumes electricity generation. With the use of computer modeling for the composition of biogas with an increased content of N2 and a reduced concentration of CH4 £ 32 %, calculations were made on the enrichment of biogas to concentrations of CH4 in it of 36–44 % due to the use of CO2 amine absorption technologies, in which the costs for the regeneration of the absorbent are compensated by the produced thermal energy of the gas piston engine of the power plant. The removal of carbon dioxide from biogas makes it possible to simultaneously increase the concentration of methane in it at the input to the heat engine, which contributes to the stable and efficient operation of the gas piston engine of the power plant and the increase in the amount of electricity generation as a result of energy utilization of landfill gas. The use of complex biogas utilization technology in the cogeneration mode allows obtaining not only electricity, but also heat, which can be used in absorption amine technologies for CO2 extraction from biogas and thus reducing carbon dioxide emissions into the atmosphere. Bibl. 17, Fig. 9, Tab. 3.

Experimental Studies on Utilization of Biogas with Biodiesel/Diesel Blends in a CI Engine

The present study covers the utilization of a gaseous alternative fuel, raw biogas, in a diesel engine. Biogas alone cannot run a diesel engine, because gaseous fuel cannot burn by compression. It can be supplied to the CI engines in dual fuel mode by using an air-biogas mixer device. In this work, it is aimed to investigate the performance and emission characteristics of a biogas-biodiesel/diesel dual fuel mode diesel engine by employing a venturi gas mixer device for providing a homogeneous mixture. The performance and emission characteristics of the engine operated by dual-fuel mode were experimentally investigated, and compared to diesel. The results indicated that biogas inducted at a flow rate of 1L/min was found to have better performance and lower emission, than that of the other flow rates. On the other hand, dual-fuel mode with a biogas flow rate of BD10 BG@1L/min showed an average reduction in BTE of 9.94% and an average increment of 8.82% in BSFC as compared to diesel. Whereas an increment in CO and HC by 5.18% and 3.01% respectively and an average reduction in NOx emissions by 14.91% as compared to diesel. Keywords: Alternative Fuel, Biogas, Biodiesel, Diesel Engine, Dual-fuel, Venturi Gas Mixer

Greenhouse Gas Mitigation Potential of the Enhanced Rice Straw Biogas System in the Philippines

Abstract Rice straw is an agricultural waste produced abundantly every rice cropping cycle. Its disposal or removal from the field is a problem to rice farmers every start of the next cropping cycle due to its labor-intensive collection from the field. One traditional practice is soil incorporation; however, rice straw does not degrade easily, and this management practice releases significant amount of greenhouse gas emissions to the environment. An attempt to solve this issue is to utilize rice straw with cattle manure as feedstock for biogas production and use the energy generated for rice post-harvest processing such as grain drying and milling. An Enhanced Rice Straw Biogas facility was constructed in Victoria, Laguna, Philippines and a trial lagoon run was conducted from June to October 2021. The data from the initial run was used as input to the modified Aston-developed Mass Energy Balance Model to determine the biogas production potential of rice straw and cattle manure as bioenergy feedstocks. The proposed system can produce 8,803,567.99 L (296.19 L/kg VS) of biogas which can be converted to 19,502.97 MW electricity and 84,512.86 MJ heat. From the energy generated per batch, 18,417.21 kg rice grain (dry season) or 15,752.79 kg rice grain (wet season) can be dried and milled, with an excess of equivalent kerosene (696.93 L for dry season or 248.46 L for wet season) and electricity (3,745.12 kWh for dry season or 6,182.23 kWh for wet season). Due to biogas utilization, an estimated 3,351 L of fossil-based kerosene and 12,185.91 kWh of electricity equivalent can be avoided. This low GHG emission rice production system (Aston Model) has a theoretical annual carbon footprint of 153,134 kg CO2e and a 28.21% reduction of greenhouse gas emissions compared to the conventional rice production system.

Waste to energy: Enhancing biogas utilization in dual-fuel engines using machine learning based prognostic analysis

Alternative fuels derived from organic matter like biomass can be a viable solution in the present scenario of increasing greenhouse gases. In the present study, waste food and animal refuse-derived biogas were tested as fuel in a diesel engine. To further enhance the waste-to-energy perspective waste cooking oil biodiesel − diesel blends were used as pilot fuel. A comprehensive set of operational settings including fuel injection timing, pressure, compression ratios, different flow rates of biogas, and engine loads were tested. Four machine learning approaches Linear Regression (LR), Decision Tree (DT), Extreme Gradient Boosting (XGBoost), and Gaussian Process Regression (GPR) were employed to develop prognostic models. The developed models for engine performance and emission were predicted with high accuracy with R2 values as high as 0.9962 for brake-specific fuel consumption and 0.9948 for brake thermal efficiency. The prediction errors were low 0.06 for BTE during model training and 0.18 during the model testing phase while it was almost negligible in the case of BSFC. All models were compared using statistical metrics and violin plots. The DT-based forecasting models were observed to be the best among all the models both based on statistical measures as well as violin plots.

Novel sulfide-driven denitrification methane oxidation (SDMO) system based on SBR-MBfR and EGSB-MBfR

Traditional denitrification process consumes external organic carbon leading to an increase in treatment costs and carbon emission. A novel sulfide-driven denitrification methane oxidation (SDMO) system, which could simultaneously utilize CH4 and H2S in biogas as electron donors for denitrification to reduce the cost and carbon emission, has been successfully operated in two kinds of reactors SBR-MBfR and EGSB-MBfR for ∼ 200 days in this study. The performance and microbial community were explored meanwhile machine learning approach have been used for predicting the complex effects on SDMO’s denitrification efficiency. Result shows SBR-MBfR’s superior performance with the maximum nitrate removal efficiency > 90 % while the denitrification rates and biological activity were also better than EGSB-MBfR. The autotrophic denitrification (Auto-D) contributed 5 % much more for nitrate removal in SBR-MBfR than EGSB-MBfR while denitrification anaerobic methane oxidation (DAMO) was more prominent in EGSB-MBfR. Nineteen machine learning models were used for operation data training and random forest regressor was demonstrated to be the optimal model for predicting nitrate removal efficiency in SDMO. According to random forest regressor’s analysis, HRT presented the highest importance in affecting SDMO nitrate removal efficiency. After the introduction of biogas for domestication, Auto-D bacteria Thiobacillus was the dominant bacteria in both systems occupying > 20 % and the abundance would increase gradually from ∼ 20 % to ∼ 60 % as H2S content rising. A hidden positive correlation between DAMO bacteria Candidatus Methylomirabilis and Thiobacillus was uncovered by mantel test analysis here, implying the integrating of Auto-D and DAMO process for nitrate removal. This study not only provides insights into the novel SDMO technology but also offers a potential advancement in simultaneously low-carbon wastewater treatment and biogas utilization.

Thermo-enviro-economic analyses of a landfill biogas-fed polygeneration process combined with a liquefied natural gas cold energy utilization unit

Landfill biogas offers a promising opportunity to supply society’s energy requirements, following the waste-to-energy approach, which issuitable for sustainable production. However, structural modification for its utilization is the main gap, requiring additional research efforts. Considering this issue, the current study aims to design an eco-friendly polygeneration method for landfill biogas utilization for a cutting-edge heat recovery system that integrates a cold energy recovery and utilization unit for liquefied natural gas. The liquefied natural gas recovery section, the organic Rankine cycle with a zeotropic mixture, and the Kalina cycle are all started using the flue gas from the combustion of biogas in a cascade process. In addition, the waste heat of the Kalina cycle is recovered by a single-effect desalination cycle and liquefied natural gas recovery section. Also, a water electrolysis process is integrated into the whole system. As a result, the products include hydrogen, electricity, natural gas, hot and cold water, and freshwater. The Aspen HYSYS software is utilized to design the system and investigate its thermodynamic, environmental, and economic aspects. The results demonstrate an energy efficiency of 57.54 % and an exergy efficiency of 18.78 %. Also, the carbon dioxide footprint associated with the system equals 0.34 kg/kWh, and the specific cost of products is 73.96 $/GJ. An optimal exergy efficiency of 25.8 % and a specific cost of products of 69.7 $/GJ are obtained by means of an intelligent optimization approach that ultimately makes use of non-dominated sorting genetic algorithm-II and artificial neural networks.

Exergetic investigation of the influence of injector location in HCCI engines utilizing DEE as pilot fuel and biogas as primary fuel

To address the global demand for sustainable energy, integrating biogas into internal combustion engines is becoming more important. Homogeneous Charge Compression Ignition (HCCI) engines, known for high efficiency and low emissions, offer a promising solution. This study investigates the optimal injector location for using biogas in HCCI engines, with diethyl ether (DEE) as the pilot fuel, evaluating three positions: (i) at the port, (ii) 6 cm away (Manifold 1), and (iii) 10 cm away (Manifold 2). Through experiments and simulations, the impact of injector location on engine performance is analyzed across various parameters, including methane fractions, engine loads, and exhaust gas compositions. Results show that port injection achieves the highest first law and exergy efficiencies but increases emissions of hydrocarbons (HC), carbon monoxide (CO), and smoke. At 15 Nm load, Manifold 1 shows a 27.34 % reduction in exergy efficiency compared to port injection, while Manifold 2 exhibits an 18.49 % decrease at higher loads. Despite lower efficiencies, Manifold 1 effectively reduces harmful emissions. The study also considers exergo-economic and sustainability aspects, highlighting that while port injection is optimal for efficiency, Manifold 1 excels in minimizing HC and CO emissions, with a 50 % reduction in HC and 71.43 % reduction in CO emissions at 15 Nm load compared to port injection. Manifold 2 achieves the lowest smoke emissions across all loads. This investigation provides crucial insights into optimizing HCCI engines for biogas utilization, emphasizing injector location, fuel composition, and operating parameters to enhance performance and reduce environmental impact.

Assessing performance variability in a dual-fuel diesel engine using diesel and biogas: an experimental study across different compression ratios

The increasing concerns about energy security and environmental sustainability have intensified the search for alternative fuels. This study investigates the performance and emission characteristics of a dual-fuel diesel engine utilizing purified biogas and diesel across various compression ratios. A single-cylinder, direct-injection, water-cooled, variable compression ratio diesel engine was adapted to operate in dual-fuel mode, running experiments at compression ratios of 12, 14, 16, 18, and 20 with a constant injection timing of 23° before top dead center under different load conditions. The study reveals a peak brake thermal efficiency of 33.25% at a compression ratio of 20, demonstrating the potential of biogas as a viable alternative fuel. Notably, while carbon monoxide and hydrocarbon emissions decreased with higher compression ratios, nitrogen oxide emissions increased, highlighting a trade-off in emission characteristics. This work contributes to the understanding of biogas utilization in diesel engines, offering insights into optimizing engine performance and emissions through compression ratio adjustments. The findings can inform future developments in sustainable energy solutions.

Renewable fuel-powered micro-gas turbine and hydrogen fuel cell systems: Exploring scenarios of technology, control, and operation

Two technology options, a proton exchange membrane (PEM) fuel cell and a recuperated micro-gas turbine (MGT) consisting of equipment with variable efficiencies and a controllable bypass valve, are modeled numerically. The validated simulations are studied under multiple scenarios, including technology, control, and operation. Under the technology scenario, the PEM fuel cell depicts higher net heat energy (1390.5 kW) with an overall efficiency of 93.27 %, significantly reducing thermal dissipation compared to the MGT, which has a low heat-to-power ratio (0.69) with the same hydrogen combustion rate (0.018 kg s−1). Following the fuel scenario, at 40 %-part load and 100 % bypass valve position, the highest net power (137.08 kW) and heat generation (635.07 kW) are achieved when 0.009 kg s−1 of hydrogen is combusted in MGT, exceeding other fuel utilization. In addition, the heating control strategy determines the availability status of the proposed technologies. The observed operational trends indicate effective fulfillment of urban heating needs by hydrogen combustion during Winter and Fall. However, the utilization of biogas leads to significant functional limitations. Finally, the operating function of the PEM fuel cell under off-design conditions is evaluated, resulting in notable enhancements in energy outputs and hydrogen consumption when considering the combination of control parameters compared to their individual evaluations.

Methylosinus trichosporium OB3b drives composition-independent application of biogas in poly(3-hydroxybutyrate) synthesis

Biological conversion of biogas into poly(3-hydroxybutyrate) (PHB) via Type II methanotrophs holds great promise. However, a prerequisite for widespread biogas utilization is a comprehensive understanding of the effects of biogas composition on methanotrophic PHB synthesis. Herein, we explore the effects of biogas composition on the microbial growth and PHB accumulation of Methylosinus trichosporium OB3b under five different artificial biogas conditions with varying the ratio of methane (CH4) to carbon dioxide (CO2), the two main components of raw biogas. Stoichiometric and kinetic analyses revealed that increased CO2 concentrations correlated with higher maximum specific growth rates (0.021–0.029 h−1) and maximum CH4 utilization rates (0.029–0.042 mg CH4/mg TSS-h). Besides, no significant correlation was found between the CH4-to-CO2 ratio and other growth parameters. Consistent PHB contents (20.2–25.3 wt%) were achieved, irrespective of the CH4-to-CO2 ratio. Furthermore, the ability of M. trichosporium OB3b to grow and synthesize PHB (13.2 wt%) was confirmed using pilot-scale biogas. Our findings highlight the potential of biogas as a feedstock for producing valuable biodegradable polymers, thus contributing to waste-derived fuel (WDF) innovation and environmental sustainability.