Biogas Plants Research Articles

Bioaugmented ensiling pretreatment to improve bioconversion of sweet sorghum: Effect of bio-additives on enzymatic saccharification and biomethane potential

This study proposes a novel strategy to integrate ensiling preservation with pretreatment of sweet sorghum (SS) biomass. Bio-additives, including cellulase, xylanase, liquid anaerobic digestate (LD), and rumen fluid (RF) were applied in ensiling process to improve the silage quality, sugar production by enzymatic hydrolysis, and anaerobic biomethane production of SS. Compared with others additives, LD could alter microbial community compositions and reduce the crystallinity of SS, thus improving ensiling pretreatment performance and achieving the highest reducing sugar yield of 84.73%. The methane production of LD silages was increased by 32.84% compared with the un-ensiled SS, indicating that ensiling pretreatment with LD could be an effective strategy to achieve the trans-seasonal preservation and improving the methane production of SS. Furthermore, taking techno-economic factors into account (energy net income of 96.07 USD/ton), LD additive was recommended for the bioaugmented ensiling pretreatment and downstream methane production of SS, which also contribute to recirculate the liquid digestate from biogas plant.

Performance Evaluation and Economic Sustainability of the PAU Model Batch Type Paddy Straw Biogas Plant

This study evaluates the performance and economic viability of the Punjab Agricultural University (PAU) Model Batch Type Paddy Straw Biogas Plant in rural India, addressing critical challenges in agricultural residue management and sustainable energy production. Data collected from two plants over four months showed an average daily biogas production of 1.46 to 3.13 m3 per day, with a total gas production of 284.8 m3 in a period of four months. Plant performance correlated moderately with ambient temperature. Economic analysis revealed annual savings of Rs. 47,600 through reduced LPG use and biogas slurry sales. The study concludes that the PAU Model is technically efficient and economically viable, offering a sustainable solution for paddy straw management and rural energy security. These findings have significant implications for policymakers and rural development practitioners in promoting sustainable agriculture and renewable energy adoption in developing regions.

Estimation of biogas potential from poultry manure to 2040 in Türkiye using time series and the artificial neural network (ANN)

The number of poultry in Türkiye constituted approximately 24 % of Europe’s total in 2020. Although Türkiye has a significant number of poultry animals, it has been relatively unsuccessful in terms of managing the associated poultry waste. The present study focuses on poultry manure-based biogas potential (PMBP), which represents an alternative means of poultry manure management in Türkiye. PMBPs were calculated for each year from 2003 to 2021, for which it was found that for 2021, Türkiye's PMBP had increased by 40 % since 2003, reaching 3469 GWh. The possible electrical energy savings that PMBP could provide for lighting, habitation, business, government offices, and industry throughout Türkiye were calculated, with PMBP spatial distribution maps for 2021 created according to geographical region and province. The province with the highest PMBP was found to be Manisa, at 390 GWh. The projected PMBPs were calculated to 2040 using the artificial neural network (ANN) and autoregressive integrated moving average (ARIMA). According to ARIMA, the PMBP for 2040 could potentially be increased by as much as 32 % from that of 2021, while according to ANN predictions, this same increase could be as much as 72 %. The ability to reduce greenhouse gas emissions resulting from poultry manure management in Türkiye through biogas production was calculated. Investors may need to prepare a feasibility study for the establishment of a biogas plant in a suitable region within Manisa province, as it has the highest PMBP among the regions evaluated.

The Economic Efficiency of Micro Biogas Plants: A Sustainable Energy Solution in Slovenia—Case Study

This paper presents a simulation model for determining the most suitable type of microbiogas plant for small local communities on Slovenian farms, focusing on the efficient processing of organic waste. This model uses various input parameters, including different types and quantities of slurry and corn silage. Four different scenarios were developed to represent potential plant sizes, each evaluated using key economic indicators: net present value, breakthrough price, and internal rate of return. A scenario sensitivity analysis was conducted to assess the effects of changes in investment costs, fluctuations in energy prices, and the addition of corn silage to the anaerobic digestion process. The results highlight significant differences in economic viability across the scenarios, with some demonstrating positive financial outcomes and shorter payback periods and others indicating potential financial risks and longer recovery times under certain conditions. The analysis suggests that smaller micro biogas plants may struggle to achieve profitability without optimizing input ratios or reducing costs, whereas larger plants show more favorable economic indicators, provided certain conditions are met. Furthermore, the economic efficiency improves when adding maize silage to the fermentor mixture.

Solar-integrated biogas reactor for efficient kitchen waste conversion to biogas

This study aimed to improve biogas production by co-digesting kitchen waste and animal manure in a solar-integrated biogas reactor. The panel then heated the substrate mixture to the right temperature for the reactor after turning solar energy into electricity. The experiment was conducted at mesophilic (37°C) and thermophilic (40°C) conditions. After 45 days of co-digestion of animal dung, kitchen trash, cow manure, and grasses, the solar-integrated biogas plant generated 1,445 mL of biogas with 60% CH4, 14% CO, and 21% other gases; in comparison, the conventional biogas digester produced 501 mL, 479 mL, and 525 mL, respectively, with 35-50% Methane, 18% CO, and 22% other gases. The data show that a solar-integrated biogas plant may react faster produce more gas, and have a higher methane concentration using kitchen waste and animal manure. An environmental effect analysis and prediction of biogas plant construction has been accomplished. The proposed biogas plant, supported by a solar-integrated reactor strategy, appears economically viable, projecting a five-year payback period. This research evaluates efficient biogas production techniques, emphasizing their importance in advancing engineering sustainability. It promotes the role of renewable energy, energy efficiency, and environmental sustainability in solving global energy problems and reducing climate change.

The Growth Performance of Spirulina platensis on Media Supplemented with Digested Poultry Droppings Slurry of Biogas Plant

The Growth Performance of Spirulina platensis on Media Supplemented with Digested Poultry Droppings Slurry of Biogas Plant

Two decades of progressive cost reduction: A paradigm for distributed solar photovoltaics and energy efficiency

The increasing deployment of renewable energy resources has led to massive energy cost effectivity worldwide in the past decade. The emergence of this cost revolution led electricity consumers to increasingly adopt distributed renewable energy resources to decrease dependence on traditional power grids. This paper applies the integrated resource planning framework, the objective of which is to design a least-cost electricity system by looking at renewable energy resources, efficient appliances, and demand response management strategies to reduce electricity bills. The results show that the commercial entity can save its electricity bill by $0.16 if it installs 6 MW solar PV over the lifetime of the solar PV plants. Besides, it was observed that wind turbines were not economically feasible to install at the site because of low wind resources. Biogas power plant is too expensive mainly because of the cost of fuel (waste). It also shows that by retrofitting 2000 compact fluorescent lamps (CFLs) with light-emitting diodes (LEDs), the company can save $0.15 million. By shifting between 0.5 MW and 1.4 MW of heating and cooling demand to periods of low tariff costs, the company can save $0.013 million annually. The climate transition plan for this company relies on PV, efficiency interventions and demand response. The study also demonstrates that an integrated resource planning framework can be used to plan a mini-grid.

Life cycle assessment of electricity from wind, photovoltaic and biogas from maize in combination with area-specific energy yields – a case study for Germany

Abstract Due to the massive expansion of renewable energy-based production capacity, the benefits and drawbacks of wind turbines, ground-mounted photovoltaic (PV) and biogas plants are currently being discussed in Germany and elsewhere. The expansion of renewable energy-based plants is competing with other uses for land area. In addition to area-specific energy yields, the environmental impact of renewables is increasingly gaining awareness. Existing research on the area-specific energy yields and environmental impact for wind, PV and biogas lacks comparability due to factors including time, location, and scale. This study addresses this research gap by combining life cycle assessment (LCA) to compare potential environmental impacts with an area-specific energy yield assessment of wind, ground-mounted PV and biogas from maize in Germany. The LCA includes an assessment of eleven midpoint and three endpoint impact indicators, while the area-specific energy yield is assessed on the basis of both gross and net area-specific energy yield. The LCA results indicate the lowest impact for wind, followed by PV and biogas. This ranking is consistent across all three endpoint and nine out of eleven midpoint categories. The same ranking also applies to the area-specific energy yield, with wind producing the most and biogas the least gross and net energy per area. These results indicate that the current political support in Germany for biogas from maize for electricity generation should be thoroughly re-evaluated in view of the more favourable alternatives, wind and PV. The findings also provide relevant insights for other regions with similar boundary conditions.

Feedstock-dependent antibiotic resistance gene patterns and expression profiles in industrial scale biogas plants revealed by meta-omics technology

This study investigated antimicrobial resistance in the anaerobic digesters of two industrial-scale biogas plants processing agricultural biomass and municipal wastewater sludge. A combination of deep sequencing and genome-centric workflow was implemented for metagenomic and metatranscriptomics data analysis to comprehensively examine potential antimicrobial resistance in microbial communities. Anaerobic microbes were found to harbour numerous antibiotic resistance genes (ARGs), with 58.85% of the metagenome-assembled genomes (MAGs) harbouring antibiotic resistance. A moderately positive correlation was observed between the abundance and expression of ARGs. ARGs were located primarily on bacterial chromosomes. A higher expression of resistance genes was observed on plasmids than on chromosomes. Risk index assessment suggests that most ARGs identified posed a significant risk to human health. However, potentially pathogenic bacteria showed lower ARG expression than non-pathogenic ones, indicating that anaerobic treatment is effective against pathogenic microbes. Resistomes at the gene category level were associated with various antibiotic resistance categories, including multidrug resistance, beta-lactams, glycopeptides, peptides, and macrolide-lincosamide-streptogramin (MLS). Differential expression analysis revealed specific genes associated with potential pathogenicity, emphasizing the importance of active gene expression in assessing the risks associated with ARGs.

Different aspects of biochar addition on semi-dry anaerobic digestion of organic fraction of municipal solid waste in continuous mode

This study investigated the use of biochar, derived from a wood gasifier, in semi-dry anaerobic digestion of organic fraction of municipal solid waste (OFMSW). The experiment was conducted in three phases, without biochar and changing the hydraulic retention time (HRT) from 50 to 15 days until first acidification condition (on pH = 6.5), with biochar at an optimal concentration of 30 g/L in HRT= 20–10 day. Also, countermeasures for the acidified reactor with biochar during the dormancy period were investigated. The results demonstrated that adding biochar led to a rapid recovery of the acidified reactor, improved stability parameters, and removed foaming as a disturbance. Biochar addition (30 g/L) enhanced the organic loading rate (OLR) up to 11 kgVS/m3.day with an HRT of 20 days leading to specific methane production of 383 L/kgVS and a volumetric production increase of biomethane by 85 %. However, at higher OLRs with HRT of 10 days, acidification condition resurfaced leading to homogeneous foaming. Excess adding of biochar did not have significant treatment effects but necessitated a no-feeding period (about 45 days) and gentle stirring with long intervals for stable conditions. Overall, the use of biochar along with the OFMSW biogas plant was demonstrated to enhance production efficiency.

Comparative analysis of life cycle assessment of biogas-powered and coal-powered power plant for optimized environmental operation

The major concerns that mankind faces today are limited reserves of conventional energy, growing energy demand, and environmental pollution. This study depicts a comparative analysis done for the life cycle assessment of the biogas-based plant and coal-based plant designed for Bikaji Foods International Ltd., India. OpenLCA version 1.11.0 software was used with the database ecoinvent 3.3 LCIA methods (ReCiPe Midpoint H) to analyze the environmental impact and investigate the effect of the biogas-based plant and the coal-based plant. The functional unit of 1 MJ of energy generated from biogas and coal was selected to represent the results of the production of 15,271,600 MJ of energy. The results for marine eutrophication, particulate matter formation, photochemical oxidant formation and terrestrial acidification for the biogas-based plant were 734.527 kg N-Eq, 6314.012 kg PM10-Eq, 1328.629 kg NMVOC and 3.933E04 kg SO2-Eq, respectively. Whereas, for coal-based plant, these values were 4919.442 kg N-Eq, 1.962E04 kg PM10-Eq, 6486.987 kg NMVOC and 13.448E04 kg SO2-Eq, respectively. The greenhouse gas emissions and fossil depletion from the biogas-based plant were found negligible as compared to the coal-based plant. Overall, it was found that the biogas-based plant has a more remunerative impact on the environment than the coal-based plant. This study recommends that local authorities and industrial communities should invest more and more in increasing the number of biogas plants at domestic as well as commercial levels and secure a clean and green future for coming generations.

Основные подходы к снижению запахового загрязнения окружающей среды предприятиями животноводства (обзор)

Modern industrial livestock production is accompanied by emissions into the environment of a wide range of odorforming substances (OFS), which negatively affect the health and quality of life of the population. The problem of protecting atmospheric air from odour pollution (OP) is of high relevance and practical significance. The review critically appraises scientific publications on the control of OP from livestock and poultry farms. Methods of control include the processing of manure with deodorizing materials (reagents, sorbents, enzymes, etc.); inoculation with microorganism strains; adjustment of animal diets; air purification from pollutants; optimization of dispersion; isolation of ОР sources; and odor masking. Agriculture’s focus on adopting green technologies has increased interest in searching environmentally friendly methods of odor control. These are the use of plant extracts, natural sorbents, effective microorganism strains, biofilters, bioscrubbers, biogas plants, planting of protective forest belts that promote the absorption of dust and dispersion of OFS. Each method of OP control has both advantages and disadvantages. Modern “green” methods effectively eliminate odors in large farms, but require high investment and operating costs, which limits their implementation in practice, and relatively low-cost methods (the use of reagents, sorbents, flavoring agents, feed additives) are usually not effective enough. An acceptable result can be obtained by combining various methods of limiting the OFS emission. Control strategies should be selected based on the source of the odor, the effectiveness of the technology on the particular farm, and the cost/benefit ratio of the odor control technology into practice.

Effect of Light Intensity on the Growth and Nutrient Uptake of the Microalga Chlorella sorokiniana Cultivated in Biogas Plant Digestate

This study investigated the effect of light intensity on the growth and nutrient uptake of Chlorella sorokiniana cultivated in nitrogen-rich anaerobic digestion wastewater. Three light intensities (20, 68, and 162 µmol m⁻2 s⁻1) were applied over a 30-day period with a 16:8 h light–dark photoperiod. The goal was to understand how light affects biomass productivity, nutrient assimilation, and biochemical composition under varying nitrogen concentrations originating from biogas plant digestate, up to 5 g L⁻1. The results showed that higher light intensities significantly boosted biomass production, achieving a five-fold increase at 162 µmol m⁻2 s⁻1 compared to 20 µmol m⁻2 s⁻1. Nutrient uptake followed a similar pattern, with 94% of ammonium nitrogen removed in 7 days under high light, compared to 55% after 30 days under low light. Phosphorus content was also completely removed after 7 days under light intensities of 68 and 162 µmol m⁻2 s⁻1. Additionally, elevated light intensity led to increased lipid accumulation (from 29.7% to 34%) and reduced protein content (from 30.9% to 26.1%), with carbohydrate content not being affected by light intensity. These findings highlight light intensity as a critical factor for optimizing microalgae cultivation in nitrogen-rich biogas digestate, promoting both effective nutrient removal and biomass production for potential bioenergy applications.

Biogas Heat Pump Power Supply Based on Smart Grid Functioning Solar Electric System Network

A comprehensive integrated solar power plant system has been developed to support the operation of a biogas plant based on a heat pump, for which fermented wort is a low-potential energy source. The change in the power factor of the solar power system connected to the grid and the temperature of the coolant entering the heat exchanger built into the methane tank are predicted. Promising solutions include changing the power of the heat pump compressor to maintain biogas production, unloading fermented wort and loading fresh material while maintaining the power factor of the grid solar system and changing the level of electricity transmission to the grid. The voltage at the input of the hybrid inverter, the voltage at the output of the frequency converter to assess their ratio and the voltage frequency are constantly measured. When changing the voltage at the input of the hybrid inverter from 240 V to 600 V, promising solutions were adopted to reduce the power of the heat pump from 3.14 kW to 1.58 kW in the production of biogas 352.5 m3/day to maintain the temperature of the heating coolant entering the heat exchanger built into the methane tank at 55° C - 45 °C in order to obtain biogas, unload fermented wort and load fresh raw materials. There is an increase in the power of electricity transmission to the grid from 0.27 to 1 and an increase in the power factor by 40% from 0.58 to 0.98. The use of the developed Smart Grid technology allows preventing peak loads of the power system, reducing electricity consumption from the grid by up to 30%.

Purification of Liquid Fraction of Digestates from Different Origins-Comparison of Polymeric and Ceramic Ultrafiltration Membranes Used for This Purpose.

Circular economy, clean technologies, and renewable energy are key to climate protection and modern environmental technology. Recovering water and valuable minerals from the liquid fraction of digestate is in line with this strategy. Digestate, a byproduct of anaerobic methane fermentation in biogas plants, is a potential source of water, minerals for fertilizers, and energy rather than waste. This study examined digestate from municipal and agricultural biogas plants and highlights the need for research on both due to their differences. The use of membrane techniques for water recovery from liquid digestate offers an innovative alternative to conventional methods. This study used standalone membrane filtration and an integrated system to produce water suitable for agricultural use. Ceramic membranes with cut-offs of 1, 5, 15, and 50 kDa and polymeric membranes of polyethersulfone and regenerated cellulose with cut-offs of 10 and 30 kDa were tested. The results showed that the membrane material significantly affects the transport and separation properties. Higher cut-off values increased permeate flux across all membranes. Ceramic membranes were more susceptible to fouling in standalone ultrafiltration, but were more effective in purifying digestate than polymeric membranes. The best results were obtained with a ceramic membrane with a 1 kDa cut-off (for example, for the integrated process and the municipal digestate, the retention rates of COD, BOD5 and DOC were 69%, 62%, and 75%, respectively).

Improving hydrolysis and acidification by regulating the oxygen status and solid content of lignocellulosic waste: Emphasis on the unsealed environment and harnessing the potential of microbial communities

The recalcitrant nature of lignocellulosic raw materials poses a challenge for current biogas plant operations, where hydrolysis and acidification (HA) are the rate-determining steps. To explore the HA balance and microbial mechanisms according to oxygen status and in conditions with relatively high solid content, we made a simple change to build an unsealed reactor. We found that the hemicellulose degradation rate increased by 149.3 % under unsealed conditions. Under microaerobic conditions (Mi), HA with more than 10 % total solid (TS) content exhibited a carbon loss rate of < 10 % in the first 7 days. In the 15 % TS Mi treatment, the organic acid conversion coefficient was 0.04, and the concentration increased to 7.4 g/L within 2 days. A high solid content was the key factor for ensuring efficient organic acid production in the early stage, whereas Mi affected the middle stage. Multiple methods revealed that abundant Prevotella and Clostridium, as well as rare Bifidobacterium, Sporacetigenium, and specific bacteria, had substantial effects on efficient organic acid production and HA balance. The correlation with Mi was 0.57–0.83. The abundance of hemicellulase genes increased by 18.41 %, and the abundance of pyruvate kinase in Mi increased by 15.55 % compared with the sealed condition, demonstrating that Mi can provide complementary advantages in the HA process. The findings in this study improved the operational quality of conventional HA and anaerobic digestion.

A sustainable design approach of a mega hostel: a study based at NIT, Srinagar, Kashmir, India

ABSTRACT In a sustainable building design, energy, water and resource optimization are key considerations, along with minimizing impacts on the ecology and environment. In this case study, water-related issues are considered from a sustainability perspective. The main objective of this study is to provide a sustainable design for a mega-hostel at the National Institute of Technology (NIT) Srinagar, with the aim of achieving an eco-friendly design which minimizes its dependence on external sources of energy. Rainwater harvesting, greywater reuse and the installation of a biogas plant are the three main techniques considered in this project. Rainfall data were collected and water demands for the mega-hostel and greywater produced by the mega-hostel were estimated. Potential rainwater harvesting, dimensions of a storage tank, first flush volume, discharges and dimensions of gutters have been calculated in this study. Greywater quantity has been calculated and a membrane bioreactor (MBR) to treat greywater is suggested, because it is space-optimized. Dimensions of a biogas plant and the quantity of gas released have also been estimated based on the amount of food waste generated by the mega-hostel.

A sustainable floating dome biogas plants integrated with semi-transparent photovoltaic thermal collectors: Construction, production and economic analysis

The design and construction of a self-sustained solar photo-voltaic active thermal heating floating dome biogas plant (35 m3) offers an alternative solution for round year biogas production, managing food and agricultural waste, reducing greenhouse gas emissions and minimize pollution. Moreover, this proposed model addresses the challenge of achieving the desired operating temperature (35 ± 2 °C) specially during the cold climatic conditions, which often leads to low gas production and high hydraulic retention time in anaerobic digestion. The integration of solar modules with the biogas digester enables the utilization of thermal energy for slurry heating and electricity for force mode of operation, ultimately enhancing overall energy efficiency. However, to assess the performance of the system, proximate and ultimate analyses as well as a cost-benefit analysis were carried out, considering revenue, and costs associated with construction, operation, and maintenance. The plant produces a significant amount of gas (9–12 m3) and hot water (∼2000 L) replacing approximately one LPG cylinder/2 day as well as organic fertilizer. The economic analysis shows a positive net present value (19.5 lakhs), an internal rate of return (20%), and short discounted payback period (5.7 years). This highlights the economic feasibility of the proposed model and emphasizes the importance of considering economic factors in the design and implementation of sustainable energy solutions. Furthermore, this approach demonstrates the potential for sustainable development and the transition to cleaner and more efficient energy systems by integrating renewable energy generation, waste management, and cost reductions.

Increasing Fertilization Efficiency of Biomass Ash by the Synergistically Acting Digestate and Extract from Water Plants Sequestering CO2 in Sorghum Crops.

The utilization of biomass ash in sustainable agriculture and increasing its fertilizing efficiency by biological agents, potentially sequestering CO2, have become important issues for the global economy. The aim of this paper was to investigate the effects of ash from sorghum (Sorghum bicolor L. Moench) and Jerusalem artichoke (Helianthus tuberosus L.) biomass, a biogas plant digestate, and a Spirodela polyrhiza extract, acting alone or synergistically, on soil fertility and the development, health and physiological properties of sorghum plants. The results show novel information concerning differences in the composition and impact of ash, depending on its origin, soil properties and sorghum plant development. Sorghum ash was more effective than that from Jerusalem artichoke. Ash used alone and preferably acting synergistically with the digestate and Spirodela polyrhiza extract greatly increased soil fertility and the growth, biomass yield and health of sorghum plants. These improvements were associated with an increased chlorophyll content in leaves, better gas exchange (photosynthesis, transpiration, stomatal conductance), greater enzyme activity (acid and alkaline phosphatase, RNase, and total dehydrogenase), and a higher biomass energy value. The developed treatments improved environmental conditions by replacing synthetic fertilizers, increasing the sequestration of CO2, solving the ash storage problem, reducing the need for pesticides, and enabling a closed circulation of nutrients between plant and soil, maintaining high soil fertility.

Determining optimal component configurations for flexible biogas plants based on power prices of 2020–2022 and the legislation framework in Germany

The aim of this study is to find optimal component configurations for flexible biogas plants considering electricity prices in Germany, for maximum annuities considering costs and revenues. Cases for solely power-price driven operation and cogeneration-led operation were investigated for electricity prices in 2020, 2021, and 2022 in hourly resolution.Additional revenue from flexible operation increases as price volatility increased from 2020 to 2022. Interestingly, the choice of capacity for the combined heat and power unit (CHPU) is determined by the expected service life of the CHPU. Irrespective of electricity market signals, power quotients (PQ) of at least PQ = 4 avoid reinvestment for the CHPU within 20 years.Another result is that the the optimality region for CHPU capacity flattens for 2022 and shift to capacities above PQ = 4. Thus, high price volatility will allow plant operators to amortise even larger CHPUs, which could stimulate the installation of peak load by flexible biogas plants. Considering the day-ahead market can provide clear recommendations for optimal component configurations.The presented Smart-Force-Optimisation (SFO) combines a prefiltering of schedules matching given constraints and a brute force optimisation to the filtered subset. Thus, SFO has an improved performance comparing to bare brute force approaches.